import React, { useState, useEffect, useMemo, useCallback, useRef } from 'react';
import {
  FilePlus,
  FolderPlus,
  Folder,
  FolderOpen,
  ChevronRight,
  ChevronDown,
  Search,
  Pin,
  Trash2,
  Check,
  Hash,
  FileText,
  Users,
  Plus,
  X,
  ExternalLink,
  Sparkles,
  ArrowLeft,
  CheckSquare,
  PanelLeftClose,
  PanelLeftOpen,
  ChevronLeft,
  Radio,
  Clock,
  AlertTriangle,
  Loader2,
  Lock,
} from 'lucide-react';
import {
  Document,
  DocumentBlock,
  DocShare,
  SharedFolder,
  TagDetails,
  TagSummary,
  Team,
  UnifiedShare,
  User,
} from '../../lib/types';
import {
  api,
  onWebSocketMessage,
  triggerHaptic,
  onRealtimeStatus,
  isRealtimeConnected,
  getRealtimeTransport,
  RealtimeTransport,
} from '../../lib/api';
import { DocSyncStatus } from '../../lib/useDocumentSync';
import { UnifiedShareModal } from '../../components/UnifiedShareModal';
import { useMobileActions } from '../../context/MobileActionContext';
import { DocumentEditor, DocSaveStatus, DocLiveState } from './DocumentEditor';

interface WorkspaceViewProps {
  currentUser?: User | null;
  initialDocId?: string | null;
  onStatsChange: () => void;
}

type WorkspaceSubView = 'editor' | 'tag_detail' | 'todos' | 'tags';

interface FolderTreeNode {
  name: string;
  fullPath: string;
  subfolders: FolderTreeNode[];
  docs: Document[];
  sharedFolderObj?: SharedFolder;
}

interface FolderTreeItemProps {
  node: FolderTreeNode;
  depth: number;
  expandedFolders: Record<string, boolean>;
  setExpandedFolders: React.Dispatch<React.SetStateAction<Record<string, boolean>>>;
  selectedDocId: string | null;
  subView: WorkspaceSubView;
  dragOverFolder: string | null;
  setDragOverFolder: (f: string | null) => void;
  handleDropOnFolder: (folderPath: string, e: React.DragEvent) => void;
  handleFolderDragStart: (e: React.DragEvent, path: string) => void;
  handleDocDragStart: (e: React.DragEvent, id: string) => void;
  handleCreateDocument: (folderPath?: string) => void;
  handleShareFolderClick: (folderPath: string, existingSf?: SharedFolder) => void;
  handleDeleteFolder: (folderPath: string) => void;
  onSelectDoc: (id: string) => void;
}

const FolderTreeItem: React.FC<FolderTreeItemProps> = ({
  node,
  depth,
  expandedFolders,
  setExpandedFolders,
  selectedDocId,
  subView,
  dragOverFolder,
  setDragOverFolder,
  handleDropOnFolder,
  handleFolderDragStart,
  handleDocDragStart,
  handleCreateDocument,
  handleShareFolderClick,
  handleDeleteFolder,
  onSelectDoc,
}) => {
  const isExpanded = Boolean(expandedFolders[node.fullPath]);
  const isDragOver = dragOverFolder === node.fullPath;
  const hasContent = node.subfolders.length > 0 || node.docs.length > 0;

  return (
    <div className="space-y-0.5">
      <div
        draggable
        onDragStart={(e) => handleFolderDragStart(e, node.fullPath)}
        onDragOver={(e) => {
          e.preventDefault();
          e.stopPropagation();
          setDragOverFolder(node.fullPath);
        }}
        onDragLeave={(e) => {
          e.preventDefault();
          if (dragOverFolder === node.fullPath) setDragOverFolder(null);
        }}
        onDrop={(e) => handleDropOnFolder(node.fullPath, e)}
        style={{ paddingLeft: `${depth * 12 + 8}px` }}
        className={`group flex items-center justify-between pr-1.5 h-7 rounded-btn text-xs cursor-pointer border-l-2 transition-colors ${
          isDragOver
            ? 'bg-accent/20 border-accent text-main font-semibold'
            : 'border-transparent hover:bg-panel-elevated text-muted'
        }`}
      >
        <button
          type="button"
          onClick={() =>
            setExpandedFolders((prev) => ({
              ...prev,
              [node.fullPath]: !prev[node.fullPath],
            }))
          }
          className="flex items-center gap-1.5 flex-1 min-w-0 text-left h-full cursor-pointer"
        >
          {hasContent ? (
            isExpanded ? (
              <ChevronDown className="w-3.5 h-3.5 text-faint shrink-0" />
            ) : (
              <ChevronRight className="w-3.5 h-3.5 text-faint shrink-0" />
            )
          ) : (
            <span className="w-3.5 shrink-0" />
          )}
          {isExpanded ? (
            <FolderOpen className="w-3.5 h-3.5 text-accent shrink-0" />
          ) : (
            <Folder className="w-3.5 h-3.5 text-accent shrink-0" />
          )}
          <span className="truncate">{node.name}</span>
          {node.sharedFolderObj && (
            <Users className="w-3 h-3 text-status-ok shrink-0" />
          )}
          <span className="text-[10px] text-faint ml-auto pr-1">
            {node.docs.length}
          </span>
        </button>

        <div className="flex items-center gap-0.5 opacity-0 group-hover:opacity-100 pointer-events-none group-hover:pointer-events-auto transition-opacity shrink-0">
          <button
            type="button"
            onClick={(e) => {
              e.stopPropagation();
              handleCreateDocument(node.fullPath);
            }}
            className="p-1 h-6 w-6 flex items-center justify-center rounded-btn hover:bg-canvas text-muted hover:text-main cursor-pointer"
            title="Notiz in diesem Ordner erstellen"
          >
            <Plus className="w-3 h-3" />
          </button>
          <button
            type="button"
            onClick={(e) => {
              e.stopPropagation();
              handleShareFolderClick(node.fullPath, node.sharedFolderObj);
            }}
            className={`p-1 h-6 w-6 flex items-center justify-center rounded-btn hover:bg-canvas cursor-pointer ${
              node.sharedFolderObj ? 'text-accent' : 'text-faint hover:text-accent'
            }`}
            title="Ordner teilen und Berechtigungen"
          >
            <Users className="w-3 h-3" />
          </button>
          <button
            type="button"
            onClick={(e) => {
              e.stopPropagation();
              handleDeleteFolder(node.fullPath);
            }}
            className="p-1 h-6 w-6 flex items-center justify-center rounded-btn hover:bg-status-err/20 text-faint hover:text-status-err cursor-pointer"
            title="Ordner löschen"
          >
            <Trash2 className="w-3 h-3" />
          </button>
        </div>
      </div>

      {isExpanded && (
        <div className="space-y-0.5">
          {/* Subfolders in this folder */}
          {node.subfolders.map((childNode) => (
            <FolderTreeItem
              key={childNode.fullPath}
              node={childNode}
              depth={depth + 1}
              expandedFolders={expandedFolders}
              setExpandedFolders={setExpandedFolders}
              selectedDocId={selectedDocId}
              subView={subView}
              dragOverFolder={dragOverFolder}
              setDragOverFolder={setDragOverFolder}
              handleDropOnFolder={handleDropOnFolder}
              handleFolderDragStart={handleFolderDragStart}
              handleDocDragStart={handleDocDragStart}
              handleCreateDocument={handleCreateDocument}
              handleShareFolderClick={handleShareFolderClick}
              handleDeleteFolder={handleDeleteFolder}
              onSelectDoc={onSelectDoc}
            />
          ))}

          {/* Notes directly in this folder */}
          {node.docs.map((d) => (
            <div
              key={d.id}
              draggable
              onDragStart={(e) => handleDocDragStart(e, d.id)}
              onClick={() => onSelectDoc(d.id)}
              style={{ paddingLeft: `${(depth + 1) * 12 + 16}px` }}
              className={`w-full flex items-center gap-2 pr-2 py-1.5 rounded-btn text-left text-xs cursor-pointer border transition-colors ${
                selectedDocId === d.id && subView === 'editor'
                  ? 'bg-panel border-accent text-main font-semibold shadow-xs'
                  : 'border-transparent text-main hover:bg-panel-elevated'
              }`}
            >
              <span className="shrink-0">{d.icon || '📝'}</span>
              <span className="truncate flex-1">{d.title || 'Unbenannte Notiz'}</span>
            </div>
          ))}

          {!hasContent && (
            <div
              style={{ paddingLeft: `${(depth + 1) * 12 + 16}px` }}
              className="py-1 text-[10px] text-faint italic"
            >
              Leer
            </div>
          )}
        </div>
      )}
    </div>
  );
};

export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
  currentUser,
  initialDocId,
  onStatsChange,
}) => {
  const [docs, setDocs] = useState<Document[]>([]);
  const [folders, setFolders] = useState<string[]>([]);
  const [sharedFolders, setSharedFolders] = useState<SharedFolder[]>([]);
  const [tagsSummary, setTagsSummary] = useState<TagSummary[]>([]);

  const [selectedDocId, setSelectedDocId] = useState<string | null>(initialDocId || null);
  const [targetBlockId, setTargetBlockId] = useState<string | null>(null);
  const [newlyCreatedDocId, setNewlyCreatedDocId] = useState<string | null>(null);
  const [subView, setSubView] = useState<WorkspaceSubView>('editor');
  const [selectedTag, setSelectedTag] = useState<string | null>(null);
  const [tagDetails, setTagDetails] = useState<TagDetails | null>(null);
  const [tagNoteDraft, setTagNoteDraft] = useState<string>('');
  const [tagSearchQuery, setTagSearchQuery] = useState<string>('');
  const [tagSortBy, setTagSortBy] = useState<'count' | 'name'>('count');

  const [searchQuery, setSearchQuery] = useState<string>('');
  const [expandedFolders, setExpandedFolders] = useState<Record<string, boolean>>({});
  const [showNewFolderModal, setShowNewFolderModal] = useState<boolean>(false);
  const [newFolderName, setNewFolderName] = useState<string>('');
  const [newFolderIsShared, setNewFolderIsShared] = useState<boolean>(false);
  const [mobileShowDetail, setMobileShowDetail] = useState<boolean>(Boolean(initialDocId));
  const [isSidebarCollapsed, setIsSidebarCollapsed] = useState<boolean>(() => {
    try {
      return localStorage.getItem('mindsift:workspace_sidebar_collapsed') === 'true';
    } catch {
      return false;
    }
  });

  const toggleSidebar = useCallback(() => {
    setIsSidebarCollapsed((prev) => {
      const next = !prev;
      try {
        localStorage.setItem('mindsift:workspace_sidebar_collapsed', String(next));
      } catch {}
      return next;
    });
  }, []);

  // Realtime connection status for top header indicator (identical to SharedListsView)
  const [realtimeConnected, setRealtimeConnected] = useState<boolean>(() => isRealtimeConnected());
  const [realtimeTransport, setRealtimeTransport] = useState<RealtimeTransport>(() => getRealtimeTransport());
  const [activeDocSyncStatus, setActiveDocSyncStatus] = useState<DocSyncStatus>('connected');
  const [docSaveStatus, setDocSaveStatus] = useState<DocSaveStatus>('saved');
  const [docSaveError, setDocSaveError] = useState<string | null>(null);
  const [docLiveState, setDocLiveState] = useState<DocLiveState>('idle');
  const [docLiveInitiator, setDocLiveInitiator] = useState<string | null>(null);
  const [showWsBlockedModal, setShowWsBlockedModal] = useState<boolean>(false);
  const liveToggleRef = useRef<(() => void) | null>(null);

  useEffect(() => {
    const unsub = onRealtimeStatus((connected, transport) => {
      setRealtimeConnected(connected);
      setRealtimeTransport(transport);
    });
    return unsub;
  }, []);

  // Drag and Drop state
  const [draggingDocId, setDraggingDocId] = useState<string | null>(null);
  const [draggingFolderPath, setDraggingFolderPath] = useState<string | null>(null);
  const [dragOverFolder, setDragOverFolder] = useState<string | null>(null);

  // Rollup drilldown & View Mode
  const [todoFolderDrilldown, setTodoFolderDrilldown] = useState<string | null>(null);
  const [todoGrouping, setTodoGrouping] = useState<'folder_note' | 'note' | 'folder'>(() => {
    return (localStorage.getItem('mindsift_todo_grouping') as any) || 'folder_note';
  });
  const [collapsedTodoFolders, setCollapsedTodoFolders] = useState<Set<string>>(new Set());
  const [collapsedTodoNotes, setCollapsedTodoNotes] = useState<Set<string>>(new Set());

  // Sharing Modal State
  const [shareModalDoc, setShareModalDoc] = useState<Document | null>(null);
  const [shareModalFolder, setShareModalFolder] = useState<SharedFolder | null>(null);
  const [activeDocShares, setActiveDocShares] = useState<DocShare[]>([]);
  const [teams, setTeams] = useState<Team[]>([]);
  const [collaborators, setCollaborators] = useState<User[]>([]);

  const isCreatingRef = useRef<boolean>(false);
  const { setGroups, setPrimaryAction } = useMobileActions();

  const loadWorkspaceData = useCallback(async () => {
    try {
      const [docsRes, foldersRes, sharedFoldersRes, tagsRes] = await Promise.all([
        api.getDocuments(),
        api.getFolders(),
        api.getSharedFolders().catch(() => []),
        api.getWorkspaceTags().catch(() => []),
      ]);
      setDocs(docsRes);
      setFolders(foldersRes);
      setSharedFolders(sharedFoldersRes);
      setTagsSummary(tagsRes);

      setSelectedDocId((prevId) => {
        if (prevId && docsRes.some((d) => d.id === prevId)) {
          return prevId;
        }
        return docsRes.length > 0 ? docsRes[0].id : null;
      });
    } catch {
      // ignore
    }
  }, []);

  useEffect(() => {
    loadWorkspaceData();
  }, [loadWorkspaceData]);

  useEffect(() => {
    if (initialDocId) {
      setSelectedDocId(initialDocId);
      setSubView('editor');
      setMobileShowDetail(true);
    }
  }, [initialDocId]);

  // Global WebSocket listener with strict isolation & deduplication
  useEffect(() => {
    const unsub = onWebSocketMessage((msg) => {
      if (msg.event === 'DOC_CREATED' && msg.payload) {
        const created = msg.payload as Document;
        // Strict Privacy Check: Only add if created by or shared with current user
        if (currentUser) {
          const isOwner = created.userId === currentUser.id;
          const isShared =
            created.sharedWith?.some(
              (s) => s.userId === currentUser.id || s.targetId === currentUser.id
            ) || false;
          const isFolderShared = Boolean(created.sharedFolderId || created.isSharedFolder);
          if (!isOwner && !isShared && !isFolderShared) {
            return;
          }
        }
        setDocs((prev) => (prev.some((d) => d.id === created.id) ? prev : [created, ...prev]));
      } else if (msg.event === 'DOC_UPDATED' && msg.payload) {
        const updated = msg.payload as Document;
        setDocs((prev) => prev.map((d) => (d.id === updated.id ? { ...d, ...updated } : d)));
      } else if (msg.event === 'DOC_DELETED' && msg.payload?.id) {
        const delId = msg.payload.id as string;
        setDocs((prev) => prev.filter((d) => d.id !== delId));
        setSelectedDocId((prev) => (prev === delId ? null : prev));
      } else if (msg.event === 'WORKSPACE_FOLDERS_UPDATED') {
        api.getFolders().then(setFolders).catch(() => {});
        api.getSharedFolders().then(setSharedFolders).catch(() => {});
        api.getDocuments().then(setDocs).catch(() => {});
      }
    });
    return unsub;
  }, [currentUser]);

  const handleCreateDocument = useCallback(
    async (folderPath = '') => {
      if (isCreatingRef.current) return;
      isCreatingRef.current = true;
      triggerHaptic(10);
      try {
        const created = await api.createDocument({
          title: 'Neue Notiz',
          icon: '📝',
          folderPath,
          blocks: [
            {
              id: `blk_${Date.now().toString(36)}_0`,
              type: 'text',
              content: '',
              level: 0,
              position: 1000,
            },
          ],
        });
        setDocs((prev) => (prev.some((d) => d.id === created.id) ? prev : [created, ...prev]));
        setNewlyCreatedDocId(created.id);
        setTargetBlockId(null);
        setSelectedDocId(created.id);
        setSubView('editor');
        setMobileShowDetail(true);
        if (folderPath) {
          setExpandedFolders((prev) => ({ ...prev, [folderPath]: true }));
        }
        onStatsChange();
      } catch {
        // ignore
      } finally {
        setTimeout(() => {
          isCreatingRef.current = false;
        }, 300);
      }
    },
    [onStatsChange]
  );

  const handleJumpToDocBlock = useCallback((docId: string, blockId?: string) => {
    setSelectedDocId(docId);
    setTargetBlockId(blockId || null);
    setNewlyCreatedDocId(null);
    setSubView('editor');
    setMobileShowDetail(true);
  }, []);

  // Register mobile FAB actions
  useEffect(() => {
    setPrimaryAction(() => handleCreateDocument(''));
    setGroups([
      {
        id: 'workspace-actions',
        title: 'Notizen & Ordner',
        items: [
          {
            id: 'new-note',
            label: 'Neue Notiz',
            icon: <FilePlus className="w-4 h-4" />,
            variant: 'accent',
            onClick: () => handleCreateDocument(''),
          },
          {
            id: 'new-folder',
            label: 'Neuer Ordner',
            icon: <FolderPlus className="w-4 h-4" />,
            onClick: () => setShowNewFolderModal(true),
          },
        ],
      },
    ]);
    return () => {
      setGroups([]);
      setPrimaryAction(undefined);
    };
  }, [handleCreateDocument, setGroups, setPrimaryAction]);

  const handleDeleteDocument = useCallback(
    async (docId: string) => {
      try {
        await api.deleteDocument(docId);
        setDocs((prev) => {
          const remaining = prev.filter((d) => d.id !== docId);
          if (selectedDocId === docId) {
            setSelectedDocId(remaining.length > 0 ? remaining[0].id : null);
          }
          return remaining;
        });
        setMobileShowDetail(false);
        onStatsChange();
      } catch {
        // ignore
      }
    },
    [onStatsChange, selectedDocId]
  );

  const handleDocMetadataChange = useCallback((updated: Document) => {
    setDocs((prev) => prev.map((d) => (d.id === updated.id ? { ...d, ...updated } : d)));
  }, []);

  const handleCreateFolderSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    const clean = newFolderName.trim().replace(/^\/+|\/+$/g, '');
    if (!clean) return;
    try {
      if (newFolderIsShared) {
        const sf = await api.createSharedFolder({ name: clean, mountPath: clean });
        setSharedFolders((prev) => [...prev, sf]);
      }
      const res = await api.createFolder(clean);
      setFolders((prev) => (prev.includes(res.path) ? prev : [...prev, res.path].sort()));
      const parts = res.path.split('/');
      let acc = '';
      const expansions: Record<string, boolean> = {};
      for (const part of parts) {
        acc = acc ? `${acc}/${part}` : part;
        expansions[acc] = true;
      }
      setExpandedFolders((prev) => ({ ...prev, ...expansions }));
      setNewFolderName('');
      setNewFolderIsShared(false);
      setShowNewFolderModal(false);
    } catch {
      // ignore
    }
  };

  const handleDeleteFolder = async (folderPath: string) => {
    try {
      const res = await api.deleteFolder(folderPath);
      setFolders((prev) =>
        prev.filter((f) => f !== folderPath && !f.startsWith(`${folderPath}/`))
      );
      if (res.deletedDocIds && res.deletedDocIds.length > 0) {
        setDocs((prev) => prev.filter((d) => !res.deletedDocIds.includes(d.id)));
        if (selectedDocId && res.deletedDocIds.includes(selectedDocId)) {
          setSelectedDocId(null);
        }
      }
      onStatsChange();
    } catch {
      // ignore
    }
  };

  // HTML5 Drag & Drop handlers for moving documents into folders
  const handleDocDragStart = (e: React.DragEvent, docId: string) => {
    e.stopPropagation();
    e.dataTransfer.setData('application/mindsift-doc-id', docId);
    e.dataTransfer.setData('text/plain', docId);
    e.dataTransfer.effectAllowed = 'move';
    setDraggingDocId(docId);
  };

  const handleFolderDragStart = (e: React.DragEvent, path: string) => {
    e.stopPropagation();
    e.dataTransfer.setData('application/mindsift-folder-path', path);
    e.dataTransfer.setData('text/plain', path);
    e.dataTransfer.effectAllowed = 'move';
    setDraggingFolderPath(path);
  };

  const handleDropOnFolder = async (targetFolder: string, e: React.DragEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setDragOverFolder(null);

    const docId = e.dataTransfer.getData('application/mindsift-doc-id') || draggingDocId;
    const folderPath = e.dataTransfer.getData('application/mindsift-folder-path') || draggingFolderPath;

    setDraggingDocId(null);
    setDraggingFolderPath(null);

    if (docId) {
      triggerHaptic(15);
      try {
        const updatedDoc = await api.moveDocument(docId, targetFolder);
        setDocs((prev) =>
          prev.map((d) => (d.id === docId ? { ...d, folderPath: updatedDoc.folderPath } : d))
        );
        if (targetFolder) {
          const parts = targetFolder.split('/');
          let acc = '';
          const expansions: Record<string, boolean> = {};
          for (const part of parts) {
            acc = acc ? `${acc}/${part}` : part;
            expansions[acc] = true;
          }
          setExpandedFolders((prev) => ({ ...prev, ...expansions }));
        }
      } catch {
        // ignore
      }
    } else if (folderPath && folderPath !== targetFolder && !targetFolder.startsWith(`${folderPath}/`)) {
      triggerHaptic(15);
      try {
        await api.moveFolder(folderPath, targetFolder);
        if (targetFolder) {
          const parts = targetFolder.split('/');
          let acc = '';
          const expansions: Record<string, boolean> = {};
          for (const part of parts) {
            acc = acc ? `${acc}/${part}` : part;
            expansions[acc] = true;
          }
          setExpandedFolders((prev) => ({ ...prev, ...expansions }));
        }
        loadWorkspaceData();
      } catch {
        // ignore
      }
    }
  };

  const handleSelectTag = useCallback(async (tag: string) => {
    const cleanTag = tag.replace(/^#/, '').toLowerCase();
    setSelectedTag(cleanTag);
    setSubView('tag_detail');
    setMobileShowDetail(true);
    try {
      const details = await api.getTagDetails(cleanTag);
      setTagDetails(details);
      setTagNoteDraft(details.noteContent || '');
    } catch {
      setTagDetails(null);
    }
  }, []);

  const handleSaveTagNote = async () => {
    if (!selectedTag) return;
    try {
      await api.updateTagPageNote(selectedTag, tagNoteDraft);
    } catch {
      // ignore
    }
  };

  const handleWikiLinkClick = useCallback(
    (pageTitle: string) => {
      const clean = pageTitle.trim().toLowerCase();
      const match = docs.find((d) => d.title.trim().toLowerCase() === clean);
      if (match) {
        setSelectedDocId(match.id);
        setSubView('editor');
        setMobileShowDetail(true);
      } else {
        handleCreateDocument('');
      }
    },
    [docs, handleCreateDocument]
  );

  const openDocShareModal = useCallback(async (doc: Document) => {
    setShareModalDoc(doc);
    setShareModalFolder(null);
    try {
      const [sharesRes, teamsRes, collabRes] = await Promise.all([
        api.getDocShares(doc.id).catch(() => []),
        api.getUserTeams().catch(() => []),
        api.getUsersDirectory().catch(() => []),
      ]);
      setActiveDocShares(sharesRes);
      setTeams(teamsRes);
      setCollaborators(collabRes);
    } catch {
      // ignore
    }
  }, []);

  const openFolderShareModal = useCallback(async (sf: SharedFolder) => {
    setShareModalFolder(sf);
    setShareModalDoc(null);
    try {
      const [teamsRes, collabRes, freshSf] = await Promise.all([
        api.getUserTeams().catch(() => []),
        api.getUsersDirectory().catch(() => []),
        api.getSharedFolder(sf.id).catch(() => sf),
      ]);
      setShareModalFolder(freshSf);
      setTeams(teamsRes);
      setCollaborators(collabRes);
    } catch {
      // ignore
    }
  }, []);

  const handleShareFolderClick = useCallback(
    async (folderPath: string, existingSf?: SharedFolder) => {
      if (existingSf) {
        openFolderShareModal(existingSf);
        return;
      }
      try {
        const clean = folderPath.trim().replace(/^\/+|\/+$/g, '');
        const sf = await api.createSharedFolder({ name: clean, mountPath: clean });
        setSharedFolders((prev) => [...prev.filter((f) => f.id !== sf.id), sf]);
        openFolderShareModal(sf);
      } catch {
        // ignore
      }
    },
    [openFolderShareModal]
  );

  const handleToggleRollupTodo = async (doc: Document, blockId: string, currentChecked: boolean) => {
    triggerHaptic(10);
    const updatedBlocks = (doc.blocks || []).map((b) =>
      b.id === blockId ? { ...b, checked: !currentChecked } : b
    );
    setDocs((prev) =>
      prev.map((d) => (d.id === doc.id ? { ...d, blocks: updatedBlocks } : d))
    );
    try {
      await api.patchDocumentBlocks(doc.id, {
        upserted: [{ id: blockId, checked: !currentChecked, type: 'todo', content: '' }],
      });
    } catch {
      loadWorkspaceData();
    }
  };

  const allFolderPaths = useMemo(() => {
    const set = new Set<string>(folders);
    for (const d of docs) {
      if (d.folderPath) set.add(d.folderPath);
    }
    for (const sf of sharedFolders) {
      if (sf.mountPath) set.add(sf.mountPath);
    }
    return Array.from(set).sort();
  }, [docs, folders, sharedFolders]);

  const filteredDocs = useMemo(() => {
    const q = searchQuery.trim().toLowerCase();
    if (!q) return docs;
    return docs.filter(
      (d) =>
        d.title.toLowerCase().includes(q) ||
        (d.content && d.content.toLowerCase().includes(q)) ||
        (d.tags && d.tags.some((t) => t.toLowerCase().includes(q)))
    );
  }, [docs, searchQuery]);

  const folderTree = useMemo(() => {
    const rootNodes: FolderTreeNode[] = [];
    const nodeMap = new Map<string, FolderTreeNode>();

    const allPathsSet = new Set<string>();
    for (const p of allFolderPaths) {
      const parts = p.split('/');
      let current = '';
      for (const part of parts) {
        current = current ? `${current}/${part}` : part;
        allPathsSet.add(current);
      }
    }

    const sortedPaths = Array.from(allPathsSet).sort((a, b) => {
      const depthA = a.split('/').length;
      const depthB = b.split('/').length;
      if (depthA !== depthB) return depthA - depthB;
      return a.localeCompare(b);
    });

    for (const p of sortedPaths) {
      const parts = p.split('/');
      const leafName = parts[parts.length - 1];
      const sharedFolderObj = sharedFolders.find(
        (sf) => sf.mountPath === p || sf.name === p
      );
      const folderDocs = filteredDocs.filter((d) => d.folderPath === p);

      const node: FolderTreeNode = {
        name: leafName,
        fullPath: p,
        subfolders: [],
        docs: folderDocs,
        sharedFolderObj,
      };
      nodeMap.set(p, node);

      if (parts.length === 1) {
        rootNodes.push(node);
      } else {
        const parentPath = parts.slice(0, -1).join('/');
        const parentNode = nodeMap.get(parentPath);
        if (parentNode) {
          parentNode.subfolders.push(node);
        } else {
          rootNodes.push(node);
        }
      }
    }

    return rootNodes;
  }, [allFolderPaths, filteredDocs, sharedFolders]);

  const pinnedDocs = useMemo(
    () => filteredDocs.filter((d) => d.isPinned),
    [filteredDocs]
  );

  const rootDocs = useMemo(
    () => filteredDocs.filter((d) => !d.folderPath),
    [filteredDocs]
  );

  // Global To-Dos rollup collections
  const allRollupTodos = useMemo(() => {
    const list: { doc: Document; blockId: string; content: string; checked: boolean }[] = [];
    for (const d of docs) {
      const fName = d.folderPath || 'Hauptebene';
      if (todoFolderDrilldown && fName !== todoFolderDrilldown) continue;
      for (const b of d.blocks || []) {
        if (b.type === 'todo' && b.content.trim() !== '') {
          list.push({ doc: d, blockId: b.id, content: b.content, checked: Boolean(b.checked) });
        }
      }
    }
    return list;
  }, [docs, todoFolderDrilldown]);

  const rollupTodosByFolder = useMemo(() => {
    const map = new Map<string, { doc: Document; blockId: string; content: string; checked: boolean }[]>();
    for (const item of allRollupTodos) {
      const fName = item.doc.folderPath || 'Hauptebene';
      const arr = map.get(fName) || [];
      arr.push(item);
      map.set(fName, arr);
    }
    return map;
  }, [allRollupTodos]);

  const rollupTodosByNote = useMemo(() => {
    const map = new Map<
      string,
      { doc: Document; items: { doc: Document; blockId: string; content: string; checked: boolean }[] }
    >();
    for (const item of allRollupTodos) {
      const existing = map.get(item.doc.id);
      if (existing) {
        existing.items.push(item);
      } else {
        map.set(item.doc.id, { doc: item.doc, items: [item] });
      }
    }
    return map;
  }, [allRollupTodos]);

  const totalOpenTodos = useMemo(() => {
    let count = 0;
    for (const d of docs) {
      for (const b of d.blocks || []) {
        if (b.type === 'todo' && !b.checked && b.content.trim() !== '') {
          count++;
        }
      }
    }
    return count;
  }, [docs]);

  // Real-time matched blocks and all nested children for the selected hashtag
  const activeTagGroups = useMemo(() => {
    if (!selectedTag) return [];
    const cleanTag = selectedTag.toLowerCase();

    const map = new Map<
      string,
      {
        docId: string;
        title: string;
        icon: string;
        folderPath: string;
        matchedBlocks: { rootBlock: DocumentBlock; children: DocumentBlock[] }[];
      }
    >();

    for (const d of docs) {
      const blks = d.blocks || [];
      if (blks.length === 0) continue;

      const matched: { rootBlock: DocumentBlock; children: DocumentBlock[] }[] = [];
      const processedChildIds = new Set<string>();

      for (let i = 0; i < blks.length; i++) {
        const b = blks[i];
        if (processedChildIds.has(b.id)) continue;

        const content = b.content || '';
        const regex = new RegExp(`(?:^|[\\s(])#(${cleanTag})(?=[\\s.,!?:;)#\\]}]|$)`, 'i');
        if (regex.test(content)) {
          const children: DocumentBlock[] = [];
          const rootLevel = b.level || 0;
          for (let j = i + 1; j < blks.length; j++) {
            const nextB = blks[j];
            if ((nextB.level || 0) > rootLevel) {
              children.push(nextB);
              processedChildIds.add(nextB.id);
            } else {
              break;
            }
          }
          matched.push({ rootBlock: b, children });
        }
      }

      if (matched.length > 0) {
        map.set(d.id, {
          docId: d.id,
          title: d.title || 'Unbenannte Notiz',
          icon: d.icon || '📝',
          folderPath: d.folderPath || '',
          matchedBlocks: matched,
        });
      }
    }

    if (tagDetails?.documents) {
      for (const dg of tagDetails.documents) {
        if (!map.has(dg.docId)) {
          map.set(dg.docId, {
            docId: dg.docId,
            title: dg.title || 'Unbenannte Notiz',
            icon: dg.icon || '📝',
            folderPath: dg.folderPath || '',
            matchedBlocks: dg.matchedBlocks || [],
          });
        }
      }
    }

    return Array.from(map.values());
  }, [docs, selectedTag, tagDetails]);

  const activeTagTotalMatches = useMemo(() => {
    let count = 0;
    for (const g of activeTagGroups) {
      count += g.matchedBlocks.length;
    }
    return count;
  }, [activeTagGroups]);

  const selectedDocObj = useMemo(
    () => docs.find((d) => d.id === selectedDocId) || null,
    [docs, selectedDocId]
  );

  const unifiedShares: UnifiedShare[] = useMemo(() => {
    if (shareModalDoc) {
      return activeDocShares.map((s) => ({
        id: s.userId || s.teamId || s.id,
        targetType: s.targetType || (s.teamId ? 'team' : 'user'),
        targetId: s.targetId || s.teamId || s.userId || '',
        targetName: s.targetName || s.displayName || s.userEmail || 'Mitglied',
        targetEmail: s.userEmail,
        permission: s.permission === 'write' ? 'editor' : 'viewer',
        createdAt: s.createdAt,
      }));
    }
    if (shareModalFolder) {
      return (shareModalFolder.shares || []).map((s) => ({
        id: s.id,
        targetType: s.targetType,
        targetId: s.targetId,
        targetName: s.targetName || s.email || 'Mitglied',
        targetEmail: s.email,
        permission: s.permission === 'write' ? 'editor' : 'viewer',
        createdAt: s.createdAt,
      }));
    }
    return [];
  }, [activeDocShares, shareModalDoc, shareModalFolder]);

  // Aggregated metadata map for every tag (documents where it occurs, open todos count)
  const tagsMetadataMap = useMemo(() => {
    const map = new Map<
      string,
      {
        tag: string;
        count: number;
        docs: { id: string; title: string; icon?: string; folderPath?: string }[];
        openTodosCount: number;
      }
    >();

    for (const t of tagsSummary) {
      const cleanTag = t.tag.toLowerCase();
      const matchingDocs: { id: string; title: string; icon?: string; folderPath?: string }[] = [];
      let openTodos = 0;

      for (const d of docs) {
        let hasInDoc = false;
        const blocks = d.blocks || [];
        for (const b of blocks) {
          const content = b.content || '';
          const regex = new RegExp(`(?:^|[\\s(])#(${cleanTag})(?=[\\s.,!?:;)#\\]}]|$)`, 'i');
          if (regex.test(content)) {
            hasInDoc = true;
            if (b.type === 'todo' && !b.checked) openTodos++;
          }
        }
        if (hasInDoc) {
          matchingDocs.push({
            id: d.id,
            title: d.title || 'Unbenannte Notiz',
            icon: d.icon,
            folderPath: d.folderPath,
          });
        }
      }

      map.set(cleanTag, {
        tag: t.tag,
        count: t.count,
        docs: matchingDocs,
        openTodosCount: openTodos,
      });
    }

    return map;
  }, [tagsSummary, docs]);

  // Filtered and sorted tags for the Kachel Grid view
  const filteredTags = useMemo(() => {
    const q = tagSearchQuery.trim().toLowerCase().replace(/^#/, '');
    let list = [...tagsSummary];
    if (q) {
      list = list.filter((t) => t.tag.toLowerCase().includes(q));
    }
    if (tagSortBy === 'count') {
      list.sort((a, b) => b.count - a.count || a.tag.localeCompare(b.tag));
    } else {
      list.sort((a, b) => a.tag.localeCompare(b.tag));
    }
    return list;
  }, [tagsSummary, tagSearchQuery, tagSortBy]);

  return (
    <div className="w-full space-y-3">
      {/* Top Header: Workspace Tabs & Actions */}
      <div className="flex flex-wrap items-center justify-between gap-2 border-b border-border pb-2">
        {/* Workspace selector tabs & left sidebar toggle */}
        <div className="flex flex-wrap items-center gap-1">
          <button
            type="button"
            disabled={subView !== 'editor'}
            onClick={subView === 'editor' ? toggleSidebar : undefined}
            className={`hidden sm:inline-flex h-8 w-8 items-center justify-center rounded-btn border transition-colors ${
              subView !== 'editor'
                ? 'opacity-35 bg-canvas border-border text-faint cursor-not-allowed pointer-events-none'
                : isSidebarCollapsed
                ? 'bg-panel border-accent text-accent cursor-pointer'
                : 'bg-canvas border-border text-muted hover:text-main cursor-pointer'
            }`}
            title={
              subView !== 'editor'
                ? 'Ordnerleiste nur im Notizen-Modus verfügbar'
                : isSidebarCollapsed
                ? 'Ordnerleiste einblenden'
                : 'Ordnerleiste einklappen'
            }
            aria-label={
              subView !== 'editor'
                ? 'Ordnerleiste nur im Notizen-Modus verfügbar'
                : isSidebarCollapsed
                ? 'Ordnerleiste einblenden'
                : 'Ordnerleiste einklappen'
            }
          >
            {isSidebarCollapsed ? (
              <PanelLeftOpen className="w-4 h-4" />
            ) : (
              <PanelLeftClose className="w-4 h-4" />
            )}
          </button>

          <button
            type="button"
            onClick={() => setSubView('editor')}
            className={`h-8 px-3 text-xs font-medium border rounded-btn transition-colors flex items-center gap-1.5 cursor-pointer ${
              subView === 'editor'
                ? 'bg-panel border-accent text-main'
                : 'bg-canvas border-border text-muted hover:text-main'
            }`}
          >
            <FileText className="w-3.5 h-3.5 text-accent" />
            <span>Notizen</span>
            {docs.length > 0 && <span className="ml-1 badge-neutral text-[10px]">{docs.length}</span>}
          </button>

          <button
            type="button"
            onClick={() => {
              setSubView('todos');
              setMobileShowDetail(true);
            }}
            className={`h-8 px-3 text-xs font-medium border rounded-btn transition-colors flex items-center gap-1.5 cursor-pointer ${
              subView === 'todos'
                ? 'bg-panel border-accent text-main'
                : 'bg-canvas border-border text-muted hover:text-main'
            }`}
          >
            <Check className="w-3.5 h-3.5 text-status-ok" />
            <span>To-Dos</span>
            {totalOpenTodos > 0 && <span className="ml-1 badge-neutral text-[10px]">{totalOpenTodos}</span>}
          </button>

          <button
            type="button"
            onClick={() => {
              setSubView('tags');
              setMobileShowDetail(true);
            }}
            className={`h-8 px-3 text-xs font-medium border rounded-btn transition-colors flex items-center gap-1.5 cursor-pointer ${
              subView === 'tags' || subView === 'tag_detail'
                ? 'bg-panel border-accent text-main'
                : 'bg-canvas border-border text-muted hover:text-main'
            }`}
          >
            <Hash className="w-3.5 h-3.5 text-accent" />
            <span>Hashtags</span>
            {tagsSummary.length > 0 && <span className="ml-1 badge-neutral text-[10px]">{tagsSummary.length}</span>}
          </button>
        </div>

        {/* Right Header Section: Save Status & Live Collaboration Button */}
        <div className="flex items-center gap-2">
          {subView === 'editor' && selectedDocId ? (
            <>
              {/* Save Status Pill */}
              <div
                className={`inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-medium border transition-colors ${
                  docSaveStatus === 'saved'
                    ? 'bg-canvas border-border text-muted'
                    : docSaveStatus === 'saving'
                    ? 'bg-panel border-accent/40 text-accent animate-pulse'
                    : docSaveStatus === 'unsaved'
                    ? 'bg-status-warn/10 border-status-warn/30 text-status-warn'
                    : 'bg-status-err/10 border-status-err/30 text-status-err'
                }`}
                title={
                  docSaveStatus === 'saved'
                    ? 'Alle Änderungen per HTTPS gesichert'
                    : docSaveStatus === 'saving'
                    ? 'Änderungen werden per HTTPS gespeichert…'
                    : docSaveStatus === 'unsaved'
                    ? 'Ungespeicherte Änderungen (Auto-Save aktiv)'
                    : docSaveError || 'Fehler beim Speichern'
                }
              >
                {docSaveStatus === 'saved' && (
                  <>
                    <Check className="w-3.5 h-3.5 text-status-ok" />
                    <span>Gespeichert</span>
                  </>
                )}
                {docSaveStatus === 'saving' && (
                  <>
                    <Loader2 className="w-3.5 h-3.5 animate-spin text-accent" />
                    <span>Speichert…</span>
                  </>
                )}
                {docSaveStatus === 'unsaved' && (
                  <>
                    <Clock className="w-3.5 h-3.5 text-status-warn" />
                    <span>Ungespeichert</span>
                  </>
                )}
                {docSaveStatus === 'error' && (
                  <>
                    <AlertTriangle className="w-3.5 h-3.5 text-status-err" />
                    <span>Fehler</span>
                  </>
                )}
              </div>

              {/* Interactive Live Collaboration Button (replaces passive radio icon) */}
              {docLiveState === 'locked_by_other' ? (
                <div
                  className="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-medium bg-status-warn/15 border border-status-warn/40 text-status-warn select-none"
                  title={`Live-Zusammenarbeit aktiv durch ${docLiveInitiator || 'anderer Nutzer'}`}
                >
                  <Lock className="w-3.5 h-3.5 shrink-0" />
                  <span className="truncate max-w-[120px]">Live: {docLiveInitiator || 'Gesperrt'}</span>
                </div>
              ) : docLiveState === 'blocked' ? (
                <button
                  type="button"
                  onClick={() => setShowWsBlockedModal(true)}
                  className="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-medium bg-status-err/15 border border-status-err/40 text-status-err hover:bg-status-err/25 transition-colors cursor-pointer"
                  title="WebSockets im Firmennetzwerk blockiert – Hier klicken für Infos"
                >
                  <AlertTriangle className="w-3.5 h-3.5 text-status-err animate-pulse shrink-0" />
                  <span>Live blockiert</span>
                </button>
              ) : docLiveState === 'connecting' ? (
                <button
                  type="button"
                  disabled
                  className="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-medium bg-amber-500/15 border border-amber-500/40 text-amber-500 opacity-80 cursor-wait"
                >
                  <Loader2 className="w-3.5 h-3.5 animate-spin text-amber-500 shrink-0" />
                  <span>Verbinde…</span>
                </button>
              ) : docLiveState === 'active' ? (
                <button
                  type="button"
                  onClick={() => liveToggleRef.current?.()}
                  className="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-semibold bg-emerald-500/15 border border-emerald-500/40 text-emerald-500 hover:bg-emerald-500/25 transition-colors cursor-pointer"
                  title="Live-Zusammenarbeit beenden (Tastendruck / WebSocket)"
                >
                  <Radio className="w-3.5 h-3.5 text-emerald-500 animate-pulse shrink-0" />
                  <span>Live aktiv</span>
                </button>
              ) : (
                <button
                  type="button"
                  onClick={() => liveToggleRef.current?.()}
                  className="inline-flex items-center gap-1.5 px-2.5 py-1 rounded-btn text-xs font-medium bg-canvas border border-border text-muted hover:text-main hover:border-accent transition-colors cursor-pointer"
                  title="Live-Zusammenarbeit aktivieren (WebSockets)"
                >
                  <Radio className="w-3.5 h-3.5 text-muted hover:text-accent shrink-0" />
                  <span>Live</span>
                </button>
              )}
            </>
          ) : (
            /* Standalone Realtime Status Indicator for Todos / Hashtags */
            (() => {
              const isConnected = realtimeConnected;
              const isSSE = realtimeTransport === 'sse';
              return (
                <div
                  className={`h-8 w-8 flex items-center justify-center rounded-btn border transition-colors ${
                    isConnected
                      ? isSSE
                        ? 'bg-teal-500/10 border-teal-500/30 text-teal-400'
                        : 'bg-emerald-500/10 border-emerald-500/30 text-emerald-500'
                      : 'bg-canvas border-border text-muted'
                  }`}
                  title={
                    isConnected
                      ? isSSE
                        ? 'Synchronisiert (Server-Sent Events / HTTPS)'
                        : 'Synchronisiert (WebSocket online)'
                      : 'Offline'
                  }
                >
                  <Radio
                    className={`w-3.5 h-3.5 ${isConnected ? 'animate-pulse' : ''}`}
                  />
                </div>
              );
            })()
          )}
        </div>
      </div>

      {/* Main Workspace Split Pane */}
      <div className="flex h-[calc(100vh-7.5rem)] bg-canvas rounded-card border border-border overflow-hidden shadow-panel">
        {/* LEFT MASTER SIDEBAR */}
        <aside
          className={`${
            subView !== 'editor' || isSidebarCollapsed
              ? 'hidden'
              : mobileShowDetail
              ? 'hidden lg:flex'
              : 'flex'
          } w-full lg:w-72 xl:w-80 shrink-0 flex-col bg-canvas border-r border-border transition-all duration-200`}
        >
          {/* Sidebar Header & Actions */}
          <div className="p-3 border-b border-border space-y-2">
            <div className="flex items-center justify-between">
              <h2 className="text-xs font-bold text-main uppercase tracking-wider">
                Notizen & Outliner
              </h2>
              <div className="flex items-center gap-1">
                <button
                  type="button"
                  onClick={() => setShowNewFolderModal(true)}
                  className="btn-action p-1 text-muted hover:text-main"
                  title="Neuer Ordner"
                >
                  <FolderPlus className="w-4 h-4" />
                </button>
                <button
                  type="button"
                  onClick={() => handleCreateDocument('')}
                  className="h-7 px-2.5 bg-canvas hover:bg-panel border border-border border-dashed rounded-btn text-xs text-muted hover:text-main inline-flex items-center gap-1 transition-colors cursor-pointer"
                  title="Neue Notiz anlegen"
                >
                  <Plus className="w-3.5 h-3.5" />
                  <span>Notiz</span>
                </button>
              </div>
            </div>

            {/* Search Input */}
            <div className="relative">
              <Search className="w-3.5 h-3.5 text-faint absolute left-2.5 top-1/2 -translate-y-1/2" />
              <input
                type="text"
                value={searchQuery}
                onChange={(e) => setSearchQuery(e.target.value)}
                placeholder="Notizen oder #Tags suchen…"
                className="input-field w-full pl-8 pr-6 py-1 text-xs"
              />
              {searchQuery && (
                <button
                  type="button"
                  onClick={() => setSearchQuery('')}
                  className="absolute right-2 top-1/2 -translate-y-1/2 text-faint hover:text-main"
                >
                  <X className="w-3.5 h-3.5" />
                </button>
              )}
            </div>
          </div>

        {/* Scrollable Navigation Tree */}
        <div className="flex-1 overflow-y-auto p-2 space-y-3">
          {/* Drop target for moving docs or folders to root */}
          {(draggingDocId || draggingFolderPath) && (
            <div
              onDragOver={(e) => {
                e.preventDefault();
                setDragOverFolder('__root__');
              }}
              onDragLeave={() => setDragOverFolder(null)}
              onDrop={(e) => handleDropOnFolder('', e)}
              className={`p-2 border-2 border-dashed rounded-btn text-center text-xs transition-colors ${
                dragOverFolder === '__root__'
                  ? 'border-accent bg-accent/20 text-main font-semibold'
                  : 'border-border text-muted bg-canvas'
              }`}
            >
              📁 In Hauptebene ablegen
            </div>
          )}

          {/* Pinned Notes */}
          {pinnedDocs.length > 0 && !searchQuery && (
            <div>
              <div className="px-2 mb-1 flex items-center gap-1 text-[10px] font-bold uppercase tracking-wider text-faint">
                <Pin className="w-3 h-3 text-status-warn" />
                <span>Angeheftet</span>
              </div>
              <div className="space-y-0.5">
                {pinnedDocs.map((d) => (
                  <div
                    key={`pin-${d.id}`}
                    draggable
                    onDragStart={(e) => handleDocDragStart(e, d.id)}
                    onClick={() => {
                      setSelectedDocId(d.id);
                      setSubView('editor');
                      setMobileShowDetail(true);
                    }}
                    className={`w-full flex items-center gap-2 px-2 py-1.5 rounded-btn text-left text-xs cursor-pointer border transition-colors ${
                      selectedDocId === d.id && subView === 'editor'
                        ? 'bg-panel border-accent text-main font-semibold shadow-xs'
                        : 'border-transparent text-main hover:bg-panel-elevated'
                    }`}
                  >
                    <span>{d.icon || '📝'}</span>
                    <span className="truncate flex-1">{d.title || 'Unbenannte Notiz'}</span>
                  </div>
                ))}
              </div>
            </div>
          )}

          {/* Folders Tree with Recursive Hierarchical Nesting */}
          {folderTree.length > 0 && (
            <div>
              <div className="px-2 mb-1 text-[10px] font-bold uppercase tracking-wider text-faint">
                Ordner
              </div>
              <div className="space-y-0.5">
                {folderTree.map((node) => (
                  <FolderTreeItem
                    key={node.fullPath}
                    node={node}
                    depth={0}
                    expandedFolders={expandedFolders}
                    setExpandedFolders={setExpandedFolders}
                    selectedDocId={selectedDocId}
                    subView={subView}
                    dragOverFolder={dragOverFolder}
                    setDragOverFolder={setDragOverFolder}
                    handleDropOnFolder={handleDropOnFolder}
                    handleFolderDragStart={handleFolderDragStart}
                    handleDocDragStart={handleDocDragStart}
                    handleCreateDocument={handleCreateDocument}
                    handleShareFolderClick={handleShareFolderClick}
                    handleDeleteFolder={handleDeleteFolder}
                    onSelectDoc={(id) => {
                      setSelectedDocId(id);
                      setTargetBlockId(null);
                      setNewlyCreatedDocId(null);
                      setSubView('editor');
                      setMobileShowDetail(true);
                    }}
                  />
                ))}
              </div>
            </div>
          )}

          {/* Root Documents */}
          <div>
            <div className="px-2 mb-1 text-[10px] font-bold uppercase tracking-wider text-faint">
              Notizen (Hauptebene)
            </div>
            {rootDocs.length === 0 ? (
              <div className="px-2 py-2 text-xs text-faint italic">
                Keine Notizen auf der Hauptebene.
              </div>
            ) : (
              <div className="space-y-0.5">
                {rootDocs.map((d) => (
                  <div
                    key={d.id}
                    draggable
                    onDragStart={(e) => handleDocDragStart(e, d.id)}
                    onClick={() => {
                      setSelectedDocId(d.id);
                      setSubView('editor');
                      setMobileShowDetail(true);
                    }}
                    className={`w-full flex items-center gap-2 px-2 py-1.5 rounded-btn text-left text-xs cursor-pointer border transition-colors ${
                      selectedDocId === d.id && subView === 'editor'
                        ? 'bg-panel border-accent text-main font-semibold shadow-xs'
                        : 'border-transparent text-main hover:bg-panel-elevated'
                    }`}
                  >
                    <span>{d.icon || '📝'}</span>
                    <span className="truncate flex-1">{d.title || 'Unbenannte Notiz'}</span>
                    {d.sharedWith && d.sharedWith.length > 0 && (
                      <Users className="w-3 h-3 text-status-ok shrink-0" />
                    )}
                  </div>
                ))}
              </div>
            )}
          </div>

          {/* Tags Explorer */}
          {tagsSummary.length > 0 && (
            <div>
              <div className="px-2 mb-1 text-[10px] font-bold uppercase tracking-wider text-faint">
                Hashtags (#)
              </div>
              <div className="flex flex-wrap gap-1 px-1">
                {tagsSummary.map((t) => (
                  <button
                    key={t.tag}
                    type="button"
                    onClick={() => handleSelectTag(t.tag)}
                    className={`inline-flex items-center gap-0.5 px-2 py-0.5 rounded-btn text-[10px] font-medium transition-colors ${
                      subView === 'tag_detail' && selectedTag === t.tag
                        ? 'bg-accent text-on-accent'
                        : 'bg-panel-elevated text-muted hover:text-accent'
                    }`}
                  >
                    <span>#{t.tag}</span>
                    <span className="opacity-60 font-mono text-[9px]">{t.count}</span>
                  </button>
                ))}
              </div>
            </div>
          )}
        </div>
      </aside>

      {/* RIGHT DETAIL AREA (STRICTLY ISOLATED BY KEY) */}
      <main
        className={`${
          subView !== 'editor' || mobileShowDetail || isSidebarCollapsed ? 'flex' : 'hidden lg:flex'
        } flex-1 flex-col min-w-0 h-full overflow-hidden bg-canvas`}
      >
        {subView === 'editor' && selectedDocId ? (
          <DocumentEditor
            key={selectedDocId}
            docId={selectedDocId}
            currentUser={currentUser}
            initialDoc={selectedDocObj}
            availableFolders={allFolderPaths}
            autoFocusTitle={newlyCreatedDocId === selectedDocId}
            initialFocusedBlockId={targetBlockId}
            onDocMetadataChange={handleDocMetadataChange}
            onDeleteDoc={handleDeleteDocument}
            onOpenShareModal={openDocShareModal}
            onSelectTag={handleSelectTag}
            onWikiLinkClick={handleWikiLinkClick}
            onBackMobile={() => setMobileShowDetail(false)}
            onSyncStatusChange={setActiveDocSyncStatus}
            onSaveStatusChange={(status, err) => {
              setDocSaveStatus(status);
              setDocSaveError(err || null);
            }}
            onLiveStateChange={(state, initiator) => {
              setDocLiveState(state);
              setDocLiveInitiator(initiator || null);
            }}
            registerLiveToggle={(handler) => {
              liveToggleRef.current = handler;
            }}
          />
        ) : subView === 'tags' ? (
          /* =========================================================================
             HASHTAG OVERVIEW & TILE DIRECTORY (KACHEL-ANSICHT MIT SUCHE)
             ========================================================================= */
          <div className="flex-1 overflow-y-auto p-4 sm:p-6 lg:p-8 bg-canvas">
            <div className="w-full space-y-5">
              {/* Header with Title and Search Controls */}
              <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-3">
                <div>
                  <div className="flex items-center gap-2">
                    <Hash className="w-5 h-5 text-accent" />
                    <h1 className="text-xl font-bold text-main">Hashtags Übersicht</h1>
                    <span className="badge-neutral text-xs font-mono">{tagsSummary.length} Tags</span>
                  </div>
                  <p className="text-xs text-muted mt-0.5">
                    Entdecke alle Themen, Schlagworte und verknüpften Blöcke aus deinen Notizen
                  </p>
                </div>

                {/* Search & Sort Toolbar */}
                <div className="flex items-center gap-2">
                  <div className="relative min-w-[200px] sm:min-w-[240px]">
                    <Search className="w-3.5 h-3.5 text-faint absolute left-2.5 top-1/2 -translate-y-1/2" />
                    <input
                      type="text"
                      value={tagSearchQuery}
                      onChange={(e) => setTagSearchQuery(e.target.value)}
                      placeholder="Hashtags durchsuchen…"
                      className="input-field w-full pl-8 pr-7 py-1.5 text-xs"
                    />
                    {tagSearchQuery && (
                      <button
                        type="button"
                        onClick={() => setTagSearchQuery('')}
                        className="absolute right-2 top-1/2 -translate-y-1/2 text-faint hover:text-main cursor-pointer"
                      >
                        <X className="w-3 h-3" />
                      </button>
                    )}
                  </div>

                  {/* Sort Mode Switcher */}
                  <div className="flex items-center bg-canvas border border-border rounded-btn p-0.5 text-[11px]">
                    <button
                      type="button"
                      onClick={() => setTagSortBy('count')}
                      className={`px-2 py-1 rounded-btn font-semibold transition-colors cursor-pointer ${
                        tagSortBy === 'count'
                          ? 'bg-panel-elevated text-main shadow-xs'
                          : 'text-muted hover:text-main'
                      }`}
                      title="Nach Häufigkeit sortieren"
                    >
                      Häufigkeit
                    </button>
                    <button
                      type="button"
                      onClick={() => setTagSortBy('name')}
                      className={`px-2 py-1 rounded-btn font-semibold transition-colors cursor-pointer ${
                        tagSortBy === 'name'
                          ? 'bg-panel-elevated text-main shadow-xs'
                          : 'text-muted hover:text-main'
                      }`}
                      title="Alphabetisch sortieren"
                    >
                      A-Z
                    </button>
                  </div>
                </div>
              </div>

              {/* Grid of Hashtag Tiles (Kacheln) */}
              {filteredTags.length === 0 ? (
                <div className="p-12 text-center text-muted text-xs space-y-2 border border-border rounded-card bg-canvas">
                  <Hash className="w-8 h-8 text-faint mx-auto" />
                  <p className="font-semibold text-main text-sm">
                    {tagSearchQuery
                      ? `Keine Hashtags für "${tagSearchQuery}" gefunden`
                      : 'Noch keine Hashtags vorhanden'}
                  </p>
                  <p className="text-faint max-w-sm mx-auto">
                    {tagSearchQuery
                      ? 'Versuche einen anderen Suchbegriff oder setze die Suche zurück.'
                      : 'Schreibe #tag in einen beliebigen Notiz-Bullet, um Themen automatisch als Kachel zu gruppieren.'}
                  </p>
                  {tagSearchQuery && (
                    <button
                      type="button"
                      onClick={() => setTagSearchQuery('')}
                      className="btn-action inline-flex items-center gap-1 px-3 py-1 text-xs text-accent mt-2 cursor-pointer"
                    >
                      Suche zurücksetzen
                    </button>
                  )}
                </div>
              ) : (
                <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 xl:grid-cols-4 2xl:grid-cols-5 gap-3.5">
                  {filteredTags.map((t) => {
                    const meta = tagsMetadataMap.get(t.tag.toLowerCase());
                    return (
                      <div
                        key={t.tag}
                        onClick={() => handleSelectTag(t.tag)}
                        className="p-4 rounded-card border border-border bg-canvas hover:border-accent hover:shadow-panel transition-all cursor-pointer group flex flex-col justify-between space-y-3"
                      >
                        <div className="space-y-2.5">
                          <div className="flex items-start justify-between gap-2">
                            <div className="flex items-center gap-2 min-w-0">
                              <span className="w-7 h-7 rounded-btn bg-accent/10 border border-accent/20 text-accent font-bold flex items-center justify-center shrink-0 text-sm group-hover:bg-accent group-hover:text-on-accent transition-colors">
                                #
                              </span>
                              <h3 className="font-bold text-sm text-main group-hover:text-accent transition-colors truncate">
                                #{t.tag}
                              </h3>
                            </div>
                            <span className="badge-neutral font-mono text-[10px] shrink-0">
                              {t.count} {t.count === 1 ? 'Treffer' : 'Treffer'}
                            </span>
                          </div>

                          {meta && meta.docs.length > 0 && (
                            <div className="space-y-1">
                              <span className="text-[10px] font-semibold text-faint uppercase tracking-wider block">
                                In {meta.docs.length} {meta.docs.length === 1 ? 'Notiz' : 'Notizen'}:
                              </span>
                              <div className="flex flex-wrap gap-1">
                                {meta.docs.slice(0, 3).map((d) => (
                                  <span
                                    key={d.id}
                                    className="inline-flex items-center gap-1 text-[11px] px-2 py-0.5 rounded-btn bg-panel-elevated text-muted truncate max-w-[140px]"
                                    title={d.title}
                                  >
                                    <span>{d.icon || '📝'}</span>
                                    <span className="truncate">{d.title}</span>
                                  </span>
                                ))}
                                {meta.docs.length > 3 && (
                                  <span className="text-[10px] text-faint self-center">
                                    +{meta.docs.length - 3}
                                  </span>
                                )}
                              </div>
                            </div>
                          )}
                        </div>

                        <div className="flex items-center justify-between pt-2.5 border-t border-border/50 text-[11px]">
                          <div>
                            {meta && meta.openTodosCount > 0 ? (
                              <span className="text-status-warn text-[10px] flex items-center gap-1 font-medium">
                                <Check className="w-2.5 h-2.5" />
                                {meta.openTodosCount} offene To-Dos
                              </span>
                            ) : (
                              <span className="text-faint text-[10px]">Blöcke & Childs anzeigen</span>
                            )}
                          </div>
                          <span className="text-accent text-xs font-semibold group-hover:translate-x-0.5 transition-transform flex items-center gap-0.5">
                            <span>Details</span>
                            <span>→</span>
                          </span>
                        </div>
                      </div>
                    );
                  })}
                </div>
              )}
            </div>
          </div>
        ) : subView === 'tag_detail' && selectedTag ? (
          <div className="flex-1 overflow-y-auto p-4 sm:p-6 lg:p-8 bg-canvas">
            <div className="w-full space-y-4">
              {/* Back to all tags */}
              <div className="flex items-center justify-between border-b border-border pb-3">
                <button
                  type="button"
                  onClick={() => setSubView('tags')}
                  className="btn-action inline-flex items-center gap-1.5 px-2.5 py-1 text-xs text-muted hover:text-main cursor-pointer"
                >
                  <ArrowLeft className="w-3.5 h-3.5" />
                  <span>Alle Hashtag-Kacheln</span>
                </button>
              </div>

              {/* Tag Context Header */}
              <div className="flex items-center justify-between">
                <div className="flex items-center gap-2">
                  <span className="w-7 h-7 rounded-btn bg-accent/10 border border-accent/20 text-accent font-bold flex items-center justify-center shrink-0 text-sm">
                    #
                  </span>
                  <h1 className="text-xl font-bold text-main">
                    #{selectedTag}
                  </h1>
                </div>
                <button
                  type="button"
                  onClick={() => setSubView('tags')}
                  className="text-xs text-accent hover:underline flex items-center gap-1 cursor-pointer"
                >
                  <ArrowLeft className="w-3 h-3" />
                  <span>Zur Kachel-Übersicht</span>
                </button>
              </div>

              {/* Tag Context Note */}
              <div className="space-y-1">
                <label className="text-[10px] font-bold uppercase tracking-wider text-faint">
                  Tag-Notiz
                </label>
                <textarea
                  rows={3}
                  value={tagNoteDraft}
                  onChange={(e) => setTagNoteDraft(e.target.value)}
                  onBlur={handleSaveTagNote}
                  placeholder={`Notizen zu #${selectedTag}…`}
                  className="input-field w-full p-2.5 text-xs text-main"
                />
              </div>

              {/* Matched Document Blocks */}
              <div className="space-y-3">
                <h3 className="text-[10px] font-bold uppercase tracking-wider text-faint">
                  Verknüpfte Outliner-Blöcke & Unterpunkte ({activeTagTotalMatches})
                </h3>
                {activeTagGroups.length === 0 ? (
                  <div className="p-8 text-center text-muted text-xs space-y-1 border border-border rounded-card bg-canvas">
                    <p className="font-semibold text-main">Keine Blöcke mit #{selectedTag} gefunden.</p>
                  </div>
                ) : (
                  activeTagGroups.map((docGroup) => {
                    const docObj = docs.find((d) => d.id === docGroup.docId);
                    return (
                      <div
                        key={docGroup.docId}
                        className="p-3 rounded-card border border-border bg-canvas space-y-2"
                      >
                        <div className="flex items-center justify-between">
                          <button
                            type="button"
                            onClick={() => handleJumpToDocBlock(docGroup.docId)}
                            className="flex items-center gap-2 text-xs font-semibold text-accent hover:underline cursor-pointer"
                          >
                            <span>{docGroup.icon || '📝'}</span>
                            <span>{docGroup.title}</span>
                            {docGroup.folderPath && (
                              <span className="badge-neutral text-[10px] font-normal">
                                📁 {docGroup.folderPath}
                              </span>
                            )}
                          </button>
                          <button
                            type="button"
                            onClick={() => handleJumpToDocBlock(docGroup.docId)}
                            className="text-[10px] text-accent hover:underline px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer flex items-center gap-1"
                            title="Notiz öffnen"
                          >
                            <span>Notiz öffnen</span>
                            <ExternalLink className="w-2.5 h-2.5" />
                          </button>
                        </div>

                        <div className="space-y-2 pl-3 border-l-2 border-border/70">
                          {docGroup.matchedBlocks.map((mb) => (
                            <div key={mb.rootBlock.id} className="space-y-1">
                              {/* Root Bullet Point containing the hashtag */}
                              <div
                                onClick={() => handleJumpToDocBlock(docGroup.docId, mb.rootBlock.id)}
                                className="flex items-start justify-between gap-1.5 text-xs text-main font-medium group cursor-pointer hover:bg-panel-elevated p-1.5 rounded-btn transition-colors"
                                title="Klick: Zu dieser Zeile springen und markieren"
                              >
                                <div className="flex items-start gap-2 flex-1 min-w-0">
                                  {mb.rootBlock.type === 'todo' ? (
                                    <button
                                      type="button"
                                      onClick={(e) => {
                                        e.stopPropagation();
                                        if (docObj) {
                                          handleToggleRollupTodo(
                                            docObj,
                                            mb.rootBlock.id,
                                            Boolean(mb.rootBlock.checked)
                                          );
                                        }
                                      }}
                                      className={`w-3.5 h-3.5 mt-0.5 checkbox-square flex items-center justify-center shrink-0 border cursor-pointer ${
                                        mb.rootBlock.checked
                                          ? 'bg-status-ok border-status-ok text-on-accent'
                                          : 'border-strong hover:border-accent text-transparent'
                                      }`}
                                    >
                                      <Check className="w-2.5 h-2.5 stroke-[3]" />
                                    </button>
                                  ) : (
                                    <span className="text-accent font-bold select-none text-sm leading-none mt-0.5">
                                      •
                                    </span>
                                  )}
                                  <span
                                    className={`flex-1 break-words ${
                                      mb.rootBlock.checked ? 'line-through text-faint' : ''
                                    }`}
                                  >
                                    {mb.rootBlock.content}
                                  </span>
                                </div>
                                <ExternalLink className="w-3 h-3 text-faint group-hover:text-accent opacity-0 group-hover:opacity-100 transition-opacity shrink-0 mt-0.5" />
                              </div>

                              {/* All Children indented */}
                              {mb.children && mb.children.length > 0 && (
                                <div className="space-y-0.5">
                                  {mb.children.map((ch) => {
                                    const relLevel = Math.max(
                                      1,
                                      (ch.level || 0) - (mb.rootBlock.level || 0)
                                    );
                                    return (
                                      <div
                                        key={ch.id}
                                        onClick={() => handleJumpToDocBlock(docGroup.docId, ch.id)}
                                        style={{ paddingLeft: `${relLevel * 16}px` }}
                                        className="flex items-start justify-between gap-1.5 text-xs text-muted hover:text-main group cursor-pointer hover:bg-panel-elevated p-1 rounded-btn transition-colors"
                                        title="Klick: Zu dieser Zeile springen und markieren"
                                      >
                                        <div className="flex items-start gap-2 flex-1 min-w-0">
                                          {ch.type === 'todo' ? (
                                            <button
                                              type="button"
                                              onClick={(e) => {
                                                e.stopPropagation();
                                                if (docObj) {
                                                  handleToggleRollupTodo(
                                                    docObj,
                                                    ch.id,
                                                    Boolean(ch.checked)
                                                  );
                                                }
                                              }}
                                              className={`w-3.5 h-3.5 mt-0.5 checkbox-square flex items-center justify-center shrink-0 border cursor-pointer ${
                                                ch.checked
                                                  ? 'bg-status-ok border-status-ok text-on-accent'
                                                  : 'border-strong hover:border-accent text-transparent'
                                              }`}
                                            >
                                              <Check className="w-2.5 h-2.5 stroke-[3]" />
                                            </button>
                                          ) : (
                                            <span className="text-faint group-hover:text-accent font-bold select-none text-xs leading-none mt-1">
                                              ◦
                                            </span>
                                          )}
                                          <span
                                            className={`flex-1 break-words ${
                                              ch.checked ? 'line-through text-faint' : ''
                                            }`}
                                          >
                                            {ch.content}
                                          </span>
                                        </div>
                                        <ExternalLink className="w-3 h-3 text-faint group-hover:text-accent opacity-0 group-hover:opacity-100 transition-opacity shrink-0 mt-0.5" />
                                      </div>
                                    );
                                  })}
                                </div>
                              )}
                            </div>
                          ))}
                        </div>
                      </div>
                    );
                  })
                )}
              </div>
            </div>
          </div>
        ) : subView === 'todos' ? (
          <div className="flex-1 overflow-y-auto p-4 sm:p-6 lg:p-8 bg-canvas">
            <div className="w-full space-y-4">
              <div className="flex flex-col sm:flex-row sm:items-center justify-between border-b border-border pb-3 gap-2">
                <div>
                  <h2 className="text-lg font-bold text-main">
                    Globaler To-Do Rollup ({totalOpenTodos} offen)
                  </h2>
                  <p className="text-xs text-muted">
                    Alle Aufgaben aus deinen Notizen im gesamten Workspace
                  </p>
                </div>

                <div className="flex flex-wrap items-center gap-2">
                  {/* View Grouping Selector */}
                  <div className="flex items-center rounded-btn bg-panel p-0.5 border border-border shadow-xs">
                    <span className="text-[10px] uppercase font-bold text-faint px-1.5 hidden sm:inline">
                      Ansicht:
                    </span>
                    <button
                      type="button"
                      onClick={() => {
                        setTodoGrouping('folder_note');
                        localStorage.setItem('mindsift_todo_grouping', 'folder_note');
                      }}
                      className={`px-2 py-1 text-[11px] font-semibold rounded-btn transition-colors cursor-pointer flex items-center gap-1 ${
                        todoGrouping === 'folder_note'
                          ? 'bg-panel-elevated text-main shadow-xs'
                          : 'text-muted hover:text-main'
                      }`}
                      title="Erst nach Ordner, dann nach Notiz gruppieren"
                    >
                      <Folder className="w-3 h-3 text-accent" />
                      <span>+</span>
                      <FileText className="w-3 h-3 text-accent" />
                      <span>Ordner & Notiz</span>
                    </button>
                    <button
                      type="button"
                      onClick={() => {
                        setTodoGrouping('note');
                        localStorage.setItem('mindsift_todo_grouping', 'note');
                      }}
                      className={`px-2 py-1 text-[11px] font-semibold rounded-btn transition-colors cursor-pointer flex items-center gap-1 ${
                        todoGrouping === 'note'
                          ? 'bg-panel-elevated text-main shadow-xs'
                          : 'text-muted hover:text-main'
                      }`}
                      title="Direkt nach Notiz gruppieren"
                    >
                      <FileText className="w-3 h-3 text-accent" />
                      <span>Notiz</span>
                    </button>
                    <button
                      type="button"
                      onClick={() => {
                        setTodoGrouping('folder');
                        localStorage.setItem('mindsift_todo_grouping', 'folder');
                      }}
                      className={`px-2 py-1 text-[11px] font-semibold rounded-btn transition-colors cursor-pointer flex items-center gap-1 ${
                        todoGrouping === 'folder'
                          ? 'bg-panel-elevated text-main shadow-xs'
                          : 'text-muted hover:text-main'
                      }`}
                      title="Nur nach Ordner gruppieren"
                    >
                      <Folder className="w-3 h-3 text-accent" />
                      <span>Ordner</span>
                    </button>
                  </div>
                </div>
              </div>

              {/* Folder Drilldown Tag */}
              {todoFolderDrilldown && (
                <div className="flex items-center justify-between p-2 rounded-btn bg-accent/10 border border-accent text-xs">
                  <span>
                    Gefiltert nach Ordner: <strong>{todoFolderDrilldown}</strong>
                  </span>
                  <button
                    type="button"
                    onClick={() => setTodoFolderDrilldown(null)}
                    className="text-accent hover:underline font-semibold cursor-pointer"
                  >
                    Filter aufheben
                  </button>
                </div>
              )}

              {/* Grouped Folders & To-Dos */}
              {allRollupTodos.length === 0 ? (
                <div className="p-8 text-center text-muted text-xs space-y-1">
                  <Sparkles className="w-6 h-6 text-accent mx-auto mb-1" />
                  <p className="font-semibold text-main">Keine To-Dos in Notizen gefunden!</p>
                  <p className="text-faint">
                    Tippe in einem beliebigen Dokument <code>/todo</code> oder <code>[] </code> ein.
                  </p>
                </div>
              ) : todoGrouping === 'note' ? (
                /* Grouped by Note directly */
                <div className="space-y-3">
                  {Array.from(rollupTodosByNote.entries()).map(([docId, { doc, items }]) => {
                    const isCollapsed = collapsedTodoNotes.has(docId);
                    const openCount = items.filter((i) => !i.checked).length;

                    return (
                      <div
                        key={docId}
                        className="border border-border rounded-card bg-canvas overflow-hidden"
                      >
                        <div className="p-2 bg-canvas border-b border-border flex items-center justify-between">
                          <div
                            onClick={() => {
                              setCollapsedTodoNotes((prev) => {
                                const next = new Set(prev);
                                if (next.has(docId)) next.delete(docId);
                                else next.add(docId);
                                return next;
                              });
                            }}
                            className="flex items-center gap-2 cursor-pointer select-none"
                          >
                            {isCollapsed ? (
                              <ChevronRight className="w-3.5 h-3.5 text-faint" />
                            ) : (
                              <ChevronDown className="w-3.5 h-3.5 text-accent" />
                            )}
                            <span className="text-sm">{doc.icon || '📝'}</span>
                            <span className="font-bold text-xs text-main">{doc.title}</span>
                            {doc.folderPath && (
                              <span className="badge-neutral text-[10px]">📁 {doc.folderPath}</span>
                            )}
                            <span className="badge-neutral text-[10px] font-mono">
                              {openCount} offen
                            </span>
                          </div>

                          <button
                            type="button"
                            onClick={() => handleJumpToDocBlock(doc.id)}
                            className="text-[10px] text-accent hover:underline px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer flex items-center gap-1"
                            title="Zur Notiz springen"
                          >
                            <span>Notiz öffnen</span>
                            <ExternalLink className="w-2.5 h-2.5" />
                          </button>
                        </div>

                        {!isCollapsed && (
                          <div className="p-2 space-y-1">
                            {items.map((item) => (
                              <div
                                key={`${item.doc.id}-${item.blockId}`}
                                className="flex items-center justify-between gap-2 p-1.5 rounded-btn hover:bg-panel-elevated text-xs transition-colors group cursor-pointer"
                              >
                                <div className="flex items-center gap-2 min-w-0 flex-1">
                                  <button
                                    type="button"
                                    onClick={(e) => {
                                      e.stopPropagation();
                                      handleToggleRollupTodo(item.doc, item.blockId, item.checked);
                                    }}
                                    className={`w-3.5 h-3.5 checkbox-square flex items-center justify-center transition-colors border cursor-pointer ${
                                      item.checked
                                        ? 'bg-status-ok border-status-ok text-on-accent'
                                        : 'border-strong hover:border-accent text-transparent'
                                    }`}
                                  >
                                    <Check className="w-2.5 h-2.5 stroke-[3]" />
                                  </button>
                                  <span
                                    onClick={() => handleJumpToDocBlock(item.doc.id, item.blockId)}
                                    className={`truncate flex-1 ${
                                      item.checked
                                        ? 'line-through text-faint'
                                        : 'text-main font-medium group-hover:text-accent'
                                    }`}
                                  >
                                    {item.content}
                                  </span>
                                </div>
                                <button
                                  type="button"
                                  onClick={() => handleJumpToDocBlock(item.doc.id, item.blockId)}
                                  className="text-faint hover:text-accent opacity-0 group-hover:opacity-100 transition-opacity p-1"
                                  title="Zu dieser Zeile springen"
                                >
                                  <ExternalLink className="w-3 h-3" />
                                </button>
                              </div>
                            ))}
                          </div>
                        )}
                      </div>
                    );
                  })}
                </div>
              ) : todoGrouping === 'folder_note' ? (
                /* Grouped by Folder -> grouped by Note */
                <div className="space-y-3">
                  {Array.from(rollupTodosByFolder.entries()).map(([folderName, items]) => {
                    const isCollapsed = collapsedTodoFolders.has(folderName);
                    const openCount = items.filter((i) => !i.checked).length;

                    // Subgroup by doc
                    const docGroupsMap = new Map<string, { doc: Document; items: typeof items }>();
                    for (const it of items) {
                      const ex = docGroupsMap.get(it.doc.id);
                      if (ex) ex.items.push(it);
                      else docGroupsMap.set(it.doc.id, { doc: it.doc, items: [it] });
                    }

                    return (
                      <div
                        key={folderName}
                        className="border border-border rounded-card bg-canvas overflow-hidden"
                      >
                        {/* Folder Header */}
                        <div className="p-2 bg-canvas border-b border-border flex items-center justify-between">
                          <div
                            onClick={() => {
                              setCollapsedTodoFolders((prev) => {
                                const next = new Set(prev);
                                if (next.has(folderName)) next.delete(folderName);
                                else next.add(folderName);
                                return next;
                              });
                            }}
                            className="flex items-center gap-2 cursor-pointer select-none"
                          >
                            {isCollapsed ? (
                              <ChevronRight className="w-3.5 h-3.5 text-faint" />
                            ) : (
                              <ChevronDown className="w-3.5 h-3.5 text-accent" />
                            )}
                            <Folder className="w-3.5 h-3.5 text-accent" />
                            <span className="font-bold text-xs text-main">{folderName}</span>
                            <span className="badge-neutral text-[10px] font-mono">
                              {openCount} offen
                            </span>
                          </div>

                          <button
                            type="button"
                            onClick={() => setTodoFolderDrilldown(folderName)}
                            className="text-[10px] text-muted hover:text-main px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer"
                            title="Diesen Ordner isolieren"
                          >
                            Nur diesen Ordner
                          </button>
                        </div>

                        {/* Folder Notes Subgroups */}
                        {!isCollapsed && (
                          <div className="p-2 space-y-3">
                            {Array.from(docGroupsMap.values()).map(({ doc, items: docItems }) => {
                              const docOpenCount = docItems.filter((i) => !i.checked).length;
                              const isDocCollapsed = collapsedTodoNotes.has(doc.id);
                              return (
                                <div
                                  key={doc.id}
                                  className="border border-border/60 rounded-btn p-2 bg-panel-elevated/30 space-y-1.5"
                                >
                                  <div className="flex items-center justify-between pb-1 border-b border-border/40">
                                    <div
                                      onClick={() => {
                                        setCollapsedTodoNotes((prev) => {
                                          const next = new Set(prev);
                                          if (next.has(doc.id)) next.delete(doc.id);
                                          else next.add(doc.id);
                                          return next;
                                        });
                                      }}
                                      className="flex items-center gap-1.5 text-xs font-semibold text-main hover:text-accent cursor-pointer select-none"
                                    >
                                      {isDocCollapsed ? (
                                        <ChevronRight className="w-3 h-3 text-faint" />
                                      ) : (
                                        <ChevronDown className="w-3 h-3 text-accent" />
                                      )}
                                      <span>{doc.icon || '📝'}</span>
                                      <span>{doc.title}</span>
                                      <span className="badge-neutral text-[9px] font-mono">
                                        {docOpenCount} offen
                                      </span>
                                    </div>

                                    <button
                                      type="button"
                                      onClick={() => handleJumpToDocBlock(doc.id)}
                                      className="text-[10px] text-accent hover:underline px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer flex items-center gap-1"
                                      title="Notiz öffnen"
                                    >
                                      <span>Notiz öffnen</span>
                                      <ExternalLink className="w-2.5 h-2.5" />
                                    </button>
                                  </div>

                                  {!isDocCollapsed && (
                                    <div className="space-y-0.5">
                                      {docItems.map((item) => (
                                        <div
                                          key={`${item.doc.id}-${item.blockId}`}
                                          className="flex items-center justify-between gap-2 p-1 rounded-btn hover:bg-canvas text-xs transition-colors group cursor-pointer"
                                        >
                                          <div className="flex items-center gap-2 min-w-0 flex-1">
                                            <button
                                              type="button"
                                              onClick={(e) => {
                                                e.stopPropagation();
                                                handleToggleRollupTodo(
                                                  item.doc,
                                                  item.blockId,
                                                  item.checked
                                                );
                                              }}
                                              className={`w-3.5 h-3.5 checkbox-square flex items-center justify-center transition-colors border cursor-pointer ${
                                                item.checked
                                                  ? 'bg-status-ok border-status-ok text-on-accent'
                                                  : 'border-strong hover:border-accent text-transparent'
                                              }`}
                                            >
                                              <Check className="w-2.5 h-2.5 stroke-[3]" />
                                            </button>
                                            <span
                                              onClick={() =>
                                                handleJumpToDocBlock(item.doc.id, item.blockId)
                                              }
                                              className={`truncate flex-1 ${
                                                item.checked
                                                  ? 'line-through text-faint'
                                                  : 'text-main font-medium group-hover:text-accent'
                                              }`}
                                            >
                                              {item.content}
                                            </span>
                                          </div>
                                          <button
                                            type="button"
                                            onClick={() =>
                                              handleJumpToDocBlock(item.doc.id, item.blockId)
                                            }
                                            className="text-faint hover:text-accent opacity-0 group-hover:opacity-100 transition-opacity p-1"
                                            title="Zu dieser Zeile springen"
                                          >
                                            <ExternalLink className="w-3 h-3" />
                                          </button>
                                        </div>
                                      ))}
                                    </div>
                                  )}
                                </div>
                              );
                            })}
                          </div>
                        )}
                      </div>
                    );
                  })}
                </div>
              ) : (
                /* Grouped by Folder (Flat tasks inside folder) */
                <div className="space-y-3">
                  {Array.from(rollupTodosByFolder.entries()).map(([folderName, items]) => {
                    const isCollapsed = collapsedTodoFolders.has(folderName);
                    const openCount = items.filter((i) => !i.checked).length;

                    return (
                      <div
                        key={folderName}
                        className="border border-border rounded-card bg-canvas overflow-hidden"
                      >
                        {/* Folder Header */}
                        <div className="p-2 bg-canvas border-b border-border flex items-center justify-between">
                          <div
                            onClick={() => {
                              setCollapsedTodoFolders((prev) => {
                                const next = new Set(prev);
                                if (next.has(folderName)) next.delete(folderName);
                                else next.add(folderName);
                                return next;
                              });
                            }}
                            className="flex items-center gap-2 cursor-pointer select-none"
                          >
                            {isCollapsed ? (
                              <ChevronRight className="w-3.5 h-3.5 text-faint" />
                            ) : (
                              <ChevronDown className="w-3.5 h-3.5 text-accent" />
                            )}
                            <Folder className="w-3.5 h-3.5 text-accent" />
                            <span className="font-bold text-xs text-main">{folderName}</span>
                            <span className="badge-neutral text-[10px] font-mono">
                              {openCount} offen
                            </span>
                          </div>

                          <button
                            type="button"
                            onClick={() => setTodoFolderDrilldown(folderName)}
                            className="text-[10px] text-muted hover:text-main px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer"
                            title="Diesen Ordner isolieren"
                          >
                            Nur diesen Ordner
                          </button>
                        </div>

                        {/* Folder Tasks */}
                        {!isCollapsed && (
                          <div className="p-2 space-y-1">
                            {items.map((item) => (
                              <div
                                key={`${item.doc.id}-${item.blockId}`}
                                className="flex items-center justify-between gap-2 p-1.5 rounded-btn hover:bg-panel-elevated text-xs transition-colors group cursor-pointer"
                              >
                                <div className="flex items-center gap-2 min-w-0 flex-1">
                                  <button
                                    type="button"
                                    onClick={(e) => {
                                      e.stopPropagation();
                                      handleToggleRollupTodo(item.doc, item.blockId, item.checked);
                                    }}
                                    className={`w-3.5 h-3.5 checkbox-square flex items-center justify-center transition-colors border cursor-pointer ${
                                      item.checked
                                        ? 'bg-status-ok border-status-ok text-on-accent'
                                        : 'border-strong hover:border-accent text-transparent'
                                    }`}
                                  >
                                    <Check className="w-2.5 h-2.5 stroke-[3]" />
                                  </button>
                                  <span
                                    onClick={() => handleJumpToDocBlock(item.doc.id, item.blockId)}
                                    className={`truncate flex-1 ${
                                      item.checked
                                        ? 'line-through text-faint'
                                        : 'text-main font-medium group-hover:text-accent'
                                    }`}
                                  >
                                    {item.content}
                                  </span>
                                </div>
                                <button
                                  type="button"
                                  onClick={() => handleJumpToDocBlock(item.doc.id, item.blockId)}
                                  className="text-[11px] text-accent hover:underline flex items-center gap-1 shrink-0 cursor-pointer"
                                  title="Zu dieser Zeile springen"
                                >
                                  <span>{item.doc.icon || '📝'}</span>
                                  <span className="truncate max-w-[120px]">{item.doc.title}</span>
                                  <ExternalLink className="w-2.5 h-2.5 opacity-60" />
                                </button>
                              </div>
                            ))}
                          </div>
                        )}
                      </div>
                    );
                  })}
                </div>
              )}
            </div>
          </div>
        ) : (
          <div className="flex-1 flex flex-col items-center justify-center p-12 text-center bg-canvas">
            <FileText className="w-10 h-10 text-faint mb-2" />
            <h3 className="text-sm font-semibold text-main mb-1">
              Keine Notiz ausgewählt
            </h3>
            <p className="text-xs text-muted max-w-sm mb-3">
              {isSidebarCollapsed
                ? 'Die Ordnerleiste ist eingeklappt. Blende sie ein oder erstelle eine neue Notiz.'
                : 'Wähle links in der Seitenleiste eine bestehende Notiz aus oder erstelle eine neue.'}
            </p>
            <div className="flex items-center gap-2">
              {isSidebarCollapsed && (
                <button
                  type="button"
                  onClick={toggleSidebar}
                  className="btn-action inline-flex items-center gap-1.5 px-3 py-1.5 text-xs font-semibold cursor-pointer"
                >
                  <PanelLeftOpen className="w-3.5 h-3.5" />
                  <span>Ordner anzeigen</span>
                </button>
              )}
              <button
                type="button"
                onClick={() => handleCreateDocument('')}
                className="btn-primary inline-flex items-center gap-1.5 px-3 py-1.5 text-xs font-semibold"
              >
                <Plus className="w-3.5 h-3.5" />
                <span>Notiz erstellen</span>
              </button>
            </div>
          </div>
        )}
      </main>

      {/* New Folder Modal */}
      {showNewFolderModal && (
        <div className="fixed inset-0 z-50 flex items-center justify-center bg-overlay backdrop-blur-sm p-4">
          <form
            onSubmit={handleCreateFolderSubmit}
            className="w-full max-w-md panel-surface shadow-panel border border-border rounded-card p-4 space-y-3"
          >
            <div className="flex items-center justify-between">
              <h3 className="text-sm font-bold text-main">
                Neuen Ordner anlegen
              </h3>
              <button
                type="button"
                onClick={() => setShowNewFolderModal(false)}
                className="p-1 rounded-btn text-faint hover:text-main"
              >
                <X className="w-4 h-4" />
              </button>
            </div>

            <div className="space-y-1">
              <label className="text-[11px] font-medium text-muted">
                Ordnerpfad (z.B. <code>Projekte/2026</code>)
              </label>
              <input
                type="text"
                autoFocus
                value={newFolderName}
                onChange={(e) => setNewFolderName(e.target.value)}
                placeholder="Projekte"
                className="input-field w-full px-2.5 py-1.5 text-xs"
              />
            </div>

            <label className="flex items-center gap-2 text-xs text-muted cursor-pointer">
              <input
                type="checkbox"
                checked={newFolderIsShared}
                onChange={(e) => setNewFolderIsShared(e.target.checked)}
                className="checkbox-square"
              />
              <span>Als geteilten Team-Ordner freigeben</span>
            </label>

            <div className="flex justify-end gap-2 pt-1">
              <button
                type="button"
                onClick={() => setShowNewFolderModal(false)}
                className="btn-action px-3 py-1 text-xs"
              >
                Abbrechen
              </button>
              <button
                type="submit"
                className="btn-primary px-3 py-1 text-xs font-semibold"
              >
                Erstellen
              </button>
            </div>
          </form>
        </div>
      )}

      {/* Unified Sharing Modal */}
      {(shareModalDoc || shareModalFolder) && (
        <UnifiedShareModal
          isOpen={true}
          onClose={() => {
            setShareModalDoc(null);
            setShareModalFolder(null);
          }}
          resourceName={shareModalDoc ? shareModalDoc.title : shareModalFolder?.name || ''}
          resourceIcon={shareModalDoc ? shareModalDoc.icon : '📁'}
          isOwner={
            shareModalDoc
              ? (shareModalDoc.isOwner || shareModalDoc.permission === 'owner')
              : Boolean(shareModalFolder?.isOwner)
          }
          currentUserId={currentUser?.id}
          shares={unifiedShares}
          teams={teams}
          collaborators={collaborators}
          onAddShare={async (targetType, targetId, permission) => {
            const perm = permission === 'editor' ? 'write' : 'read';
            if (shareModalDoc) {
              await api.createDocShare(
                shareModalDoc.id,
                targetType === 'team'
                  ? { teamId: targetId, permission: perm }
                  : { userId: targetId, permission: perm }
              );
              const updatedShares = await api.getDocShares(shareModalDoc.id);
              setActiveDocShares(updatedShares);
            } else if (shareModalFolder) {
              await api.createFolderShare(shareModalFolder.id, {
                targetType,
                targetId,
                permission: perm,
              });
              const updatedFolder = await api.getSharedFolder(shareModalFolder.id);
              setShareModalFolder(updatedFolder);
            }
          }}
          onRemoveShare={async (shareId) => {
            if (shareModalDoc) {
              await api.deleteDocShare(shareModalDoc.id, shareId);
              const updatedShares = await api.getDocShares(shareModalDoc.id);
              setActiveDocShares(updatedShares);
            } else if (shareModalFolder) {
              await api.deleteFolderShare(shareModalFolder.id, shareId);
              const updatedFolder = await api.getSharedFolder(shareModalFolder.id);
              setShareModalFolder(updatedFolder);
            }
          }}
        />
      )}

      {/* WebSocket Blocked Modal */}
      {showWsBlockedModal && (
        <div className="fixed inset-0 z-50 flex items-center justify-center p-4 bg-black/60 backdrop-blur-xs animate-in fade-in duration-150">
          <div className="w-full max-w-md bg-canvas border border-border rounded-card shadow-modal p-6 space-y-4">
            <div className="flex items-start gap-3">
              <div className="w-10 h-10 rounded-full bg-status-err/15 flex items-center justify-center shrink-0">
                <AlertTriangle className="w-5 h-5 text-status-err" />
              </div>
              <div className="flex-1">
                <h3 className="text-sm font-bold text-main">
                  WebSockets in diesem Netzwerk blockiert
                </h3>
                <p className="text-xs text-muted mt-1 leading-relaxed">
                  Deine Firewall oder dein Firmen-Proxy blockiert WebSocket-Verbindungen (<code className="text-accent bg-panel px-1 py-0.5 rounded">ws://</code> / <code className="text-accent bg-panel px-1 py-0.5 rounded">wss://</code>).
                </p>
              </div>
            </div>

            <div className="bg-surface-subtle border border-border rounded-btn p-3 text-xs space-y-2 text-main">
              <div className="flex items-center gap-2 text-status-ok font-semibold">
                <Check className="w-4 h-4 shrink-0" />
                <span>Kein Datenverlust: Auto-Save per HTTPS ist aktiv!</span>
              </div>
              <p className="text-muted leading-relaxed">
                Jede getippte Zeile und alle Änderungen werden zuverlässig über Standard-HTTPS-Anfragen im Hintergrund gespeichert.
              </p>
              <p className="text-muted text-[11px] leading-relaxed">
                Lediglich die gleichzeitige Tastendruck-Echtzeitanzeige mit anderen Nutzern im selben Moment ist ohne WebSockets eingeschränkt.
              </p>
            </div>

            <div className="flex justify-end pt-2">
              <button
                type="button"
                onClick={() => setShowWsBlockedModal(false)}
                className="btn-action px-4 py-1.5 text-xs font-semibold bg-accent text-on-accent hover:opacity-90 transition-opacity cursor-pointer"
              >
                Verstanden
              </button>
            </div>
          </div>
        </div>
      )}
      </div>
    </div>
  );
};