'use client';

import { useState, useEffect, useCallback } from 'react';
import { Document, Folder, DocumentType, DEFAULT_FOLDERS } from '@/types/documents';

const generateId = () => Math.random().toString(36).substring(2, 9);

// Transform Supabase row to Document type
const transformRowToDocument = (row: any): Document => ({
  id: row.id,
  title: row.title,
  content: row.content,
  type: row.type as DocumentType,
  folder: row.folder || 'General',
  tags: row.tags || [],
  createdAt: row.created_at,
  updatedAt: row.updated_at,
  size: row.size || 0,
  description: row.description,
});

const getInitialFolders = (): Folder[] =>
  DEFAULT_FOLDERS.map((name) => ({
    id: generateId(),
    name,
    count: 0,
  }));

// Helper to fetch with timeout
async function fetchWithTimeout(url: string, options: RequestInit = {}, timeoutMs = 10000) {
  const controller = new AbortController();
  const timeoutId = setTimeout(() => controller.abort(), timeoutMs);
  
  try {
    const response = await fetch(url, {
      ...options,
      signal: controller.signal,
    });
    clearTimeout(timeoutId);
    return response;
  } catch (error) {
    clearTimeout(timeoutId);
    throw error;
  }
}

export function useDocuments() {
  const [documents, setDocuments] = useState<Document[]>([]);
  const [folders, setFolders] = useState<Folder[]>([]);
  const [isLoaded, setIsLoaded] = useState(false);
  const [error, setError] = useState<string | null>(null);

  // Load from API on mount
  useEffect(() => {
    let isMounted = true;
    
    async function loadDocuments() {
      try {
        console.log('[useDocuments] Starting fetch...');
        
        const response = await fetchWithTimeout('/api/documents', {
          headers: {
            'Cache-Control': 'no-cache',
          },
          cache: 'no-store',
        }, 10000);

        console.log('[useDocuments] Response status:', response.status);

        // Try to parse JSON even if response is not ok (to get error details)
        let result;
        try {
          result = await response.json();
        } catch (parseErr) {
          throw new Error(`Failed to parse response: ${response.statusText}`);
        }

        console.log('[useDocuments] API response:', result);

        if (!response.ok) {
          throw new Error(result.error || `HTTP error! status: ${response.status}`);
        }

        if (!isMounted) return;

        if (result.error) {
          console.error('[useDocuments] API returned error:', result.error);
          setError(result.error);
          setDocuments([]);
        } else if (result.documents && Array.isArray(result.documents)) {
          console.log(`[useDocuments] Loaded ${result.documents.length} documents`);
          setDocuments(result.documents.map(transformRowToDocument));
          setError(null);
        } else {
          console.log('[useDocuments] No documents found or invalid format');
          setDocuments([]);
          setError(null);
        }
      } catch (err: any) {
        console.error('[useDocuments] Exception:', err);
        if (!isMounted) return;
        
        if (err.name === 'AbortError') {
          setError('Request timed out. Please check your connection and try again.');
        } else {
          setError(err.message || 'Failed to load documents');
        }
        setDocuments([]);
      } finally {
        if (isMounted) {
          console.log('[useDocuments] Setting isLoaded to true');
          setIsLoaded(true);
        }
      }
    }

    loadDocuments();
    
    return () => {
      isMounted = false;
    };
  }, []);

  // Initialize folders (local only for now)
  useEffect(() => {
    setFolders(getInitialFolders());
  }, []);

  // Update folder counts whenever documents change
  useEffect(() => {
    setFolders((prev) =>
      prev.map((folder) => ({
        ...folder,
        count: documents.filter((d) => d.folder === folder.name).length,
      }))
    );
  }, [documents]);

  const createDocument = useCallback(
    async (doc: Omit<Document, 'id' | 'createdAt' | 'updatedAt' | 'size'>): Promise<Document | null> => {
      // TODO: Implement via API
      console.log('Create document not yet implemented');
      return null;
    },
    []
  );

  const updateDocument = useCallback(
    async (id: string, updates: Partial<Omit<Document, 'id' | 'createdAt'>>): Promise<Document | null> => {
      // TODO: Implement via API
      console.log('Update document not yet implemented');
      return null;
    },
    []
  );

  const deleteDocument = useCallback(async (id: string): Promise<boolean> => {
    try {
      const response = await fetchWithTimeout(`/api/documents?id=${encodeURIComponent(id)}`, {
        method: 'DELETE',
      }, 10000);

      let result: any = null;
      try {
        result = await response.json();
      } catch {
        // Best effort parse; fall back to status text below.
      }

      if (!response.ok) {
        throw new Error(result?.error || `HTTP error! status: ${response.status}`);
      }

      setDocuments((prev) => prev.filter((doc) => doc.id !== id));
      setError(null);
      return true;
    } catch (err: any) {
      console.error('[useDocuments] Delete failed:', err);
      setError(err?.message || 'Failed to delete document');
      return false;
    }
  }, []);

  const createFolder = useCallback((name: string): Folder => {
    const newFolder: Folder = {
      id: generateId(),
      name,
      count: 0,
    };
    setFolders((prev) => [...prev, newFolder]);
    return newFolder;
  }, []);

  const deleteFolder = useCallback(
    async (folderId: string): Promise<boolean> => {
      const folder = folders.find((f) => f.id === folderId);
      if (!folder) return false;
      setFolders((prev) => prev.filter((f) => f.id !== folderId));
      return true;
    },
    [folders]
  );

  const getDocumentById = useCallback(
    (id: string): Document | undefined => {
      return documents.find((d) => d.id === id);
    },
    [documents]
  );

  const getRecentDocuments = useCallback(
    (limit = 5): Document[] => {
      return [...documents]
        .sort((a, b) => new Date(b.updatedAt).getTime() - new Date(a.updatedAt).getTime())
        .slice(0, limit);
    },
    [documents]
  );

  const getAllTags = useCallback((): string[] => {
    const tags = new Set<string>();
    documents.forEach((doc) => doc.tags.forEach((tag) => tags.add(tag)));
    return Array.from(tags).sort();
  }, [documents]);

  // Refresh documents from API
  const refreshDocuments = useCallback(async () => {
    setIsLoaded(false);
    // Re-trigger the effect by toggling a state (simplified)
    window.location.reload();
  }, []);

  return {
    documents,
    folders,
    isLoaded,
    error,
    createDocument,
    updateDocument,
    deleteDocument,
    createFolder,
    deleteFolder,
    getDocumentById,
    getRecentDocuments,
    getAllTags,
    refreshDocuments,
  };
}