import type { Presentation, PresentationMetadata, CreatePresentationRequest } from '../types/presentation';

const DB_NAME = 'SlideshareDB';
const DB_VERSION = 1;
const PRESENTATIONS_STORE = 'presentations';

/**
 * Initialize IndexedDB database
 */
export const initializeDB = (): Promise<IDBDatabase> => {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open(DB_NAME, DB_VERSION);
    
    request.onerror = () => {
      reject(new Error('Failed to open IndexedDB database'));
    };
    
    request.onsuccess = () => {
      resolve(request.result);
    };
    
    request.onupgradeneeded = (event) => {
      const db = (event.target as IDBOpenDBRequest).result;
      
      // Create presentations object store
      if (!db.objectStoreNames.contains(PRESENTATIONS_STORE)) {
        const store = db.createObjectStore(PRESENTATIONS_STORE, { keyPath: 'metadata.id' });
        
        // Create indexes for efficient querying
        store.createIndex('name', 'metadata.name', { unique: false });
        store.createIndex('theme', 'metadata.theme', { unique: false });
        store.createIndex('createdAt', 'metadata.createdAt', { unique: false });
        store.createIndex('updatedAt', 'metadata.updatedAt', { unique: false });
      }
    };
  });
};

/**
 * Generate a unique ID for presentations
 */
const generatePresentationId = (): string => {
  return `presentation_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
};

/**
 * Create a new presentation
 */
export const createPresentation = async (request: CreatePresentationRequest): Promise<Presentation> => {
  const db = await initializeDB();
  
  const now = new Date().toISOString();
  const presentation: Presentation = {
    metadata: {
      id: generatePresentationId(),
      name: request.name,
      description: request.description,
      theme: request.theme,
      aspectRatio: request.aspectRatio,
      createdAt: now,
      updatedAt: now
    },
    slides: []
  };
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readwrite');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    
    const request = store.add(presentation);
    
    request.onerror = () => {
      reject(new Error('Failed to create presentation'));
    };
    
    request.onsuccess = () => {
      resolve(presentation);
    };
    
    transaction.onerror = () => {
      reject(new Error('Transaction failed while creating presentation'));
    };
  });
};

/**
 * Get all presentations
 */
export const getAllPresentations = async (): Promise<Presentation[]> => {
  const db = await initializeDB();
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readonly');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    
    const request = store.getAll();
    
    request.onerror = () => {
      reject(new Error('Failed to retrieve presentations'));
    };
    
    request.onsuccess = () => {
      // Sort by creation date (newest first)
      const presentations = request.result.sort((a: Presentation, b: Presentation) => 
        new Date(b.metadata.createdAt).getTime() - new Date(a.metadata.createdAt).getTime()
      );
      resolve(presentations);
    };
  });
};

/**
 * Get a presentation by ID
 */
export const getPresentationById = async (id: string): Promise<Presentation | null> => {
  const db = await initializeDB();
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readonly');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    
    const request = store.get(id);
    
    request.onerror = () => {
      reject(new Error('Failed to retrieve presentation'));
    };
    
    request.onsuccess = () => {
      resolve(request.result || null);
    };
  });
};

/**
 * Update a presentation
 */
export const updatePresentation = async (presentation: Presentation): Promise<Presentation> => {
  const db = await initializeDB();
  
  // Update the updatedAt timestamp
  presentation.metadata.updatedAt = new Date().toISOString();
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readwrite');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    
    const request = store.put(presentation);
    
    request.onerror = () => {
      reject(new Error('Failed to update presentation'));
    };
    
    request.onsuccess = () => {
      resolve(presentation);
    };
  });
};

/**
 * Delete a presentation
 */
export const deletePresentation = async (id: string): Promise<void> => {
  const db = await initializeDB();
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readwrite');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    
    const request = store.delete(id);
    
    request.onerror = () => {
      reject(new Error('Failed to delete presentation'));
    };
    
    request.onsuccess = () => {
      resolve();
    };
  });
};

/**
 * Get presentations by theme
 */
export const getPresentationsByTheme = async (theme: string): Promise<Presentation[]> => {
  const db = await initializeDB();
  
  return new Promise((resolve, reject) => {
    const transaction = db.transaction([PRESENTATIONS_STORE], 'readonly');
    const store = transaction.objectStore(PRESENTATIONS_STORE);
    const index = store.index('theme');
    
    const request = index.getAll(theme);
    
    request.onerror = () => {
      reject(new Error('Failed to retrieve presentations by theme'));
    };
    
    request.onsuccess = () => {
      // Sort by creation date (newest first)
      const presentations = request.result.sort((a: Presentation, b: Presentation) => 
        new Date(b.metadata.createdAt).getTime() - new Date(a.metadata.createdAt).getTime()
      );
      resolve(presentations);
    };
  });
};

/**
 * Get presentation metadata only (for listing views)
 */
export const getPresentationMetadata = async (): Promise<PresentationMetadata[]> => {
  const presentations = await getAllPresentations();
  return presentations.map(p => p.metadata);
};