package storage

import (
	"database/sql"
	"errors"

	"github.com/sandrodach/mindsift/internal/domain"
)

// Deleted notes go to a trash first (documents.is_archived = 1). Trashed notes vanish from the tree,
// search, export, stats and for everyone they were shared with; their owner can still read them,
// restore them or delete them for good. archived_by records who trashed the note (the owner, or the
// owner of the shared folder it lived in), so that person sees it in their trash as well.

// ErrNotInTrash is returned when restoring or purging a note that is not in the user's trash.
var ErrNotInTrash = errors.New("Notiz nicht im Papierkorb")

// ErrDocInTrash refuses changes to a trashed note; it has to be restored first.
var ErrDocInTrash = errors.New("Die Notiz liegt im Papierkorb. Stelle sie zuerst wieder her.")

// TrashedDocument is one entry of the trash list.
type TrashedDocument struct {
	ID         string `json:"id"`
	Title      string `json:"title"`
	Icon       string `json:"icon"`
	FolderPath string `json:"folderPath"`
	DeletedAt  string `json:"deletedAt"`
	IsOwner    bool   `json:"isOwner"`
}

const trashScope = `is_archived = 1 AND (user_id = ? OR archived_by = ?)`

func trashStmts(userID, docID string) []sqlStmt {
	return []sqlStmt{
		stmt(`UPDATE documents SET is_archived = 1, archived_at = ?, archived_by = ? WHERE id = ?`, domain.NowISO(), userID, docID),
		stmt(`DELETE FROM doc_pins WHERE doc_id = ?`, docID),
	}
}

func (s *Store) trashDocument(userID, docID string) error {
	return s.execInTx(trashStmts(userID, docID)...)
}

// GetTrash lists the notes in the user's trash, newest deletion first.
func (s *Store) GetTrash(userID string) ([]TrashedDocument, error) {
	rows, err := s.db.Query(`SELECT d.id, d.title, d.icon, d.folder_path, d.shared_folder_id, d.sub_folder_path, d.archived_at, d.user_id,
		       COALESCE(wsf.name, '')
		FROM documents d LEFT JOIN workspace_shared_folders wsf ON wsf.id = d.shared_folder_id
		WHERE d.`+trashScope+` ORDER BY d.archived_at DESC`, userID, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	out := []TrashedDocument{}
	for rows.Next() {
		var t TrashedDocument
		var sharedFolderID, subPath, ownerID, folderName string
		if err := rows.Scan(&t.ID, &t.Title, &t.Icon, &t.FolderPath, &sharedFolderID, &subPath, &t.DeletedAt, &ownerID, &folderName); err != nil {
			continue
		}
		if sharedFolderID != "" {
			t.FolderPath = folderName
			if subPath != "" {
				t.FolderPath += "/" + subPath
			}
		}
		t.IsOwner = ownerID == userID
		out = append(out, t)
	}
	return out, nil
}

func (s *Store) trashedDocOwner(userID, docID string) (string, error) {
	var owner string
	err := s.db.QueryRow(`SELECT user_id FROM documents WHERE id = ? AND `+trashScope, docID, userID, userID).Scan(&owner)
	if err == sql.ErrNoRows {
		return "", ErrNotInTrash
	}
	return owner, err
}

// RestoreDocument takes a note out of the trash. Its folder is created again if it was deleted in the
// meantime; a shared folder that no longer exists puts the note back into the owner's top level.
func (s *Store) RestoreDocument(userID, docID string) error {
	owner, err := s.trashedDocOwner(userID, docID)
	if err != nil {
		return err
	}
	var folderPath, sharedFolderID string
	_ = s.db.QueryRow(`SELECT folder_path, shared_folder_id FROM documents WHERE id = ?`, docID).Scan(&folderPath, &sharedFolderID)
	if sharedFolderID != "" {
		var exists int
		_ = s.db.QueryRow(`SELECT COUNT(*) FROM workspace_shared_folders WHERE id = ?`, sharedFolderID).Scan(&exists)
		if exists == 0 {
			if _, err := s.db.Exec(`UPDATE documents SET shared_folder_id = '', sub_folder_path = '', folder_path = '' WHERE id = ?`, docID); err != nil {
				return err
			}
		}
	} else if folderPath != "" {
		if _, err := s.CreateFolder(owner, folderPath); err != nil {
			return err
		}
	}
	_, err = s.db.Exec(`UPDATE documents SET is_archived = 0, archived_at = '', archived_by = '' WHERE id = ?`, docID)
	return err
}

// PurgeDocument deletes a trashed note for good.
func (s *Store) PurgeDocument(userID, docID string) error {
	if _, err := s.trashedDocOwner(userID, docID); err != nil {
		return err
	}
	return s.hardDeleteDocument(docID)
}

// EmptyTrash deletes every note in the user's trash for good and returns their IDs.
func (s *Store) EmptyTrash(userID string) ([]string, error) {
	items, err := s.GetTrash(userID)
	if err != nil {
		return nil, err
	}
	ids := make([]string, 0, len(items))
	for _, t := range items {
		if err := s.hardDeleteDocument(t.ID); err != nil {
			return ids, err
		}
		ids = append(ids, t.ID)
	}
	return ids, nil
}

func (s *Store) hardDeleteDocument(docID string) error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	for _, q := range []string{
		// Tasks created from blocks of this note keep existing without the link
		`UPDATE thoughts SET converted_type = '', converted_ref_id = '' WHERE converted_type = 'document_block'
		  AND substr(converted_ref_id, 1, instr(converted_ref_id, ':') - 1) = ?`,
		`DELETE FROM blocks WHERE document_id = ?`,
		`DELETE FROM block_tags WHERE document_id = ?`,
		`DELETE FROM doc_pins WHERE doc_id = ?`,
		`DELETE FROM doc_shares WHERE doc_id = ?`,
		`DELETE FROM doc_team_shares WHERE doc_id = ?`,
		`DELETE FROM doc_user_folders WHERE doc_id = ?`,
		`DELETE FROM documents WHERE id = ?`,
	} {
		if _, err := tx.Exec(q, docID); err != nil {
			return err
		}
	}
	return tx.Commit()
}