import React, { useState, useMemo, useRef, useEffect } from 'react';
import Prism from 'prismjs';
import 'prismjs/components/prism-python';
import 'prismjs/components/prism-typescript';
import 'prismjs/components/prism-bash';
import 'prismjs/components/prism-json';
import 'prismjs/components/prism-go';
import 'prismjs/components/prism-sql';
import 'prismjs/components/prism-yaml';
import 'prismjs/components/prism-rust';
import 'prismjs/components/prism-c';
import 'prismjs/components/prism-cpp';
import 'prismjs/components/prism-java';
import 'prismjs/components/prism-php';
import 'prismjs/components/prism-docker';
import 'prismjs/components/prism-markdown';
import { Code, Copy, Check, Eye, Edit3 } from 'lucide-react';
import { DocumentBlock } from '../../lib/types';

export interface CodeBlockItemProps {
  block: DocumentBlock;
  isReadOnly: boolean;
  onChangeContent: (content: string) => void;
  onChangeLang: (lang: string) => void;
  onFocus?: () => void;
  onBlur?: () => void;
  inputRef?: (el: HTMLTextAreaElement | null) => void;
}

export const CODE_LANGUAGES = [
  { id: 'javascript', label: 'JavaScript' },
  { id: 'typescript', label: 'TypeScript' },
  { id: 'python', label: 'Python' },
  { id: 'go', label: 'Go' },
  { id: 'bash', label: 'Bash / Shell' },
  { id: 'json', label: 'JSON' },
  { id: 'html', label: 'HTML / XML', alias: 'markup' },
  { id: 'css', label: 'CSS' },
  { id: 'sql', label: 'SQL' },
  { id: 'rust', label: 'Rust' },
  { id: 'cpp', label: 'C++' },
  { id: 'c', label: 'C' },
  { id: 'java', label: 'Java' },
  { id: 'php', label: 'PHP' },
  { id: 'yaml', label: 'YAML' },
  { id: 'docker', label: 'Dockerfile' },
  { id: 'markdown', label: 'Markdown' },
  { id: 'text', label: 'Plain Text' },
];

export const CodeBlockItem: React.FC<CodeBlockItemProps> = ({
  block,
  isReadOnly,
  onChangeContent,
  onChangeLang,
  onFocus,
  onBlur,
  inputRef,
}) => {
  const [isEditing, setIsEditing] = useState(false);
  const [copied, setCopied] = useState(false);
  const localTextareaRef = useRef<HTMLTextAreaElement | null>(null);

  const currentLang = block.lang || 'javascript';

  // Highlighted HTML generated by Prism
  const highlightedCode = useMemo(() => {
    const code = block.content || '';
    if (!code) return '';

    const prismLang = currentLang === 'html' ? 'markup' : currentLang;
    const grammar = Prism.languages[prismLang] || Prism.languages.javascript;
    if (!grammar) {
      return code
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;');
    }
    try {
      return Prism.highlight(code, grammar, prismLang);
    } catch {
      return code
        .replace(/&/g, '&amp;')
        .replace(/</g, '&lt;')
        .replace(/>/g, '&gt;');
    }
  }, [block.content, currentLang]);

  // Code lines for line numbers
  const lines = useMemo(() => {
    return (block.content || '').split('\n');
  }, [block.content]);

  const handleCopy = async (e: React.MouseEvent) => {
    e.stopPropagation();
    try {
      await navigator.clipboard.writeText(block.content || '');
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {
      // Fallback
    }
  };

  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    if (e.key === 'Escape') {
      setIsEditing(false);
      return;
    }
    // Tab key indent/outdent
    if (e.key === 'Tab') {
      e.preventDefault();
      const textarea = e.currentTarget;
      const start = textarea.selectionStart;
      const end = textarea.selectionEnd;
      const val = textarea.value;

      if (e.shiftKey) {
        if (val.substring(start - 2, start) === '  ') {
          const newVal = val.substring(0, start - 2) + val.substring(start);
          onChangeContent(newVal);
          setTimeout(() => {
            textarea.selectionStart = textarea.selectionEnd = Math.max(0, start - 2);
          }, 0);
        }
      } else {
        const newVal = val.substring(0, start) + '  ' + val.substring(end);
        onChangeContent(newVal);
        setTimeout(() => {
          textarea.selectionStart = textarea.selectionEnd = start + 2;
        }, 0);
      }
    }
  };

  const switchToEdit = () => {
    if (isReadOnly) return;
    setIsEditing(true);
    setTimeout(() => {
      localTextareaRef.current?.focus();
    }, 20);
  };

  return (
    <div className="rounded-card border border-border bg-panel overflow-hidden shadow-xs my-1 group/code">
      {/* Code Block Header Toolbar */}
      <div className="flex items-center justify-between px-3 py-1.5 bg-canvas border-b border-border text-xs">
        {/* Left: Language Selection */}
        <div className="flex items-center gap-2">
          <Code className="w-3.5 h-3.5 text-accent flex-shrink-0" />
          <select
            value={currentLang}
            disabled={isReadOnly}
            onChange={(e) => onChangeLang(e.target.value)}
            className="bg-transparent text-main font-mono text-[11px] font-medium border border-transparent hover:border-border focus:border-accent rounded px-1.5 py-0.5 outline-none cursor-pointer"
          >
            {CODE_LANGUAGES.map((lang) => (
              <option key={lang.id} value={lang.id} className="bg-panel text-main">
                {lang.label}
              </option>
            ))}
          </select>
        </div>

        {/* Right: Mode Toggle & Copy */}
        <div className="flex items-center gap-1.5">
          {!isReadOnly && (
            <button
              type="button"
              onClick={() => {
                if (isEditing) {
                  setIsEditing(false);
                } else {
                  switchToEdit();
                }
              }}
              className="px-2 py-0.5 rounded text-[11px] font-medium text-muted hover:text-main hover:bg-panel-elevated transition-colors flex items-center gap-1 cursor-pointer"
              title={isEditing ? 'Zur farbigen Vorschau wechseln (Esc)' : 'Code bearbeiten'}
            >
              {isEditing ? (
                <>
                  <Eye className="w-3 h-3 text-accent" />
                  <span>Vorschau</span>
                </>
              ) : (
                <>
                  <Edit3 className="w-3 h-3 text-muted" />
                  <span>Bearbeiten</span>
                </>
              )}
            </button>
          )}

          <button
            type="button"
            onClick={handleCopy}
            className={`px-2 py-0.5 rounded text-[11px] font-medium transition-colors flex items-center gap-1 cursor-pointer ${
              copied
                ? 'text-emerald-500 bg-emerald-500/10'
                : 'text-muted hover:text-main hover:bg-panel-elevated'
            }`}
            title="Code in Zwischenablage kopieren"
          >
            {copied ? (
              <>
                <Check className="w-3 h-3 text-emerald-500" />
                <span>Kopiert!</span>
              </>
            ) : (
              <>
                <Copy className="w-3 h-3 opacity-70" />
                <span>Kopieren</span>
              </>
            )}
          </button>
        </div>
      </div>

      {/* Code Block Content */}
      {isEditing && !isReadOnly ? (
        <div className="relative">
          <textarea
            ref={(el) => {
              localTextareaRef.current = el;
              if (inputRef) inputRef(el);
            }}
            rows={Math.max(3, lines.length)}
            value={block.content || ''}
            onFocus={() => onFocus && onFocus()}
            onBlur={() => {
              if (onBlur) onBlur();
            }}
            onChange={(e) => onChangeContent(e.target.value)}
            onKeyDown={handleKeyDown}
            placeholder="// Code hier eingeben..."
            className="w-full p-3 bg-panel-elevated/40 font-mono text-xs text-main leading-relaxed focus:outline-none resize-none placeholder:text-faint"
          />
          <div className="px-3 py-1 bg-canvas/40 border-t border-border/50 text-[10px] text-faint flex items-center justify-between">
            <span>Tab: Einrücken (2 Leerzeichen) • Shift+Tab: Ausrücken</span>
            <button
              type="button"
              onClick={() => setIsEditing(false)}
              className="hover:text-accent cursor-pointer"
            >
              Vorschau anzeigen (Esc)
            </button>
          </div>
        </div>
      ) : (
        <div
          onClick={switchToEdit}
          className={`relative p-3 font-mono text-xs overflow-x-auto ${
            isReadOnly ? '' : 'cursor-pointer hover:bg-panel-elevated/20 transition-colors'
          }`}
          title={isReadOnly ? undefined : 'Klicken zum Bearbeiten'}
        >
          {block.content ? (
            <div className="flex gap-3">
              {/* Line numbers */}
              <div className="select-none text-right text-faint opacity-50 font-mono text-xs leading-relaxed flex-shrink-0">
                {lines.map((_, idx) => (
                  <div key={idx}>{idx + 1}</div>
                ))}
              </div>
              {/* Syntax highlighted code */}
              <pre className="m-0 p-0 font-mono text-xs leading-relaxed whitespace-pre overflow-x-auto flex-1">
                <code
                  dangerouslySetInnerHTML={{ __html: highlightedCode }}
                  className={`language-${currentLang}`}
                />
              </pre>
            </div>
          ) : (
            <div className="text-faint italic py-2">
              {isReadOnly ? '(Kein Code hinterlegt)' : '(Klicken, um Code einzugeben...)'}
            </div>
          )}
        </div>
      )}
    </div>
  );
};