/**
 * IndexedDB database for project storage
 */

export const DB_NAME = 'audio-editor-db';
export const DB_VERSION = 1;

export interface ProjectMetadata {
  id: string;
  name: string;
  description?: string;
  createdAt: number;
  updatedAt: number;
  duration: number; // Total project duration in seconds
  sampleRate: number;
  trackCount: number;
  thumbnail?: string; // Base64 encoded waveform thumbnail
}

export interface SerializedAudioBuffer {
  sampleRate: number;
  length: number;
  numberOfChannels: number;
  channelData: Float32Array[]; // Array of channel data
}

export interface SerializedTrack {
  id: string;
  name: string;
  color: string;
  volume: number;
  pan: number;
  muted: boolean;
  soloed: boolean;
  collapsed: boolean;
  height: number;
  audioBuffer: SerializedAudioBuffer | null;
  effects: any[]; // Effect chain
  automation: any; // Automation data
  recordEnabled: boolean;
}

export interface ProjectData {
  metadata: ProjectMetadata;
  tracks: SerializedTrack[];
  settings: {
    zoom: number;
    currentTime: number;
    sampleRate: number;
  };
}

/**
 * Initialize IndexedDB database
 */
export function initDB(): Promise<IDBDatabase> {
  return new Promise((resolve, reject) => {
    const request = indexedDB.open(DB_NAME, DB_VERSION);

    request.onerror = () => reject(request.error);
    request.onsuccess = () => resolve(request.result);

    request.onupgradeneeded = (event) => {
      const db = (event.target as IDBOpenDBRequest).result;

      // Create projects object store
      if (!db.objectStoreNames.contains('projects')) {
        const projectStore = db.createObjectStore('projects', { keyPath: 'metadata.id' });
        projectStore.createIndex('updatedAt', 'metadata.updatedAt', { unique: false });
        projectStore.createIndex('name', 'metadata.name', { unique: false });
      }

      // Create audio buffers object store (for large files)
      if (!db.objectStoreNames.contains('audioBuffers')) {
        db.createObjectStore('audioBuffers', { keyPath: 'id' });
      }
    };
  });
}

/**
 * Get all projects (metadata only for list view)
 */
export async function getAllProjects(): Promise<ProjectMetadata[]> {
  const db = await initDB();

  return new Promise((resolve, reject) => {
    const transaction = db.transaction(['projects'], 'readonly');
    const store = transaction.objectStore('projects');
    const index = store.index('updatedAt');
    const request = index.openCursor(null, 'prev'); // Most recent first

    const projects: ProjectMetadata[] = [];

    request.onsuccess = () => {
      const cursor = request.result;
      if (cursor) {
        projects.push(cursor.value.metadata);
        cursor.continue();
      } else {
        resolve(projects);
      }
    };

    request.onerror = () => reject(request.error);
  });
}

/**
 * Save project to IndexedDB
 */
export async function saveProject(project: ProjectData): Promise<void> {
  const db = await initDB();

  return new Promise((resolve, reject) => {
    const transaction = db.transaction(['projects'], 'readwrite');
    const store = transaction.objectStore('projects');
    const request = store.put(project);

    request.onsuccess = () => resolve();
    request.onerror = () => reject(request.error);
  });
}

/**
 * Load project from IndexedDB
 */
export async function loadProject(projectId: string): Promise<ProjectData | null> {
  const db = await initDB();

  return new Promise((resolve, reject) => {
    const transaction = db.transaction(['projects'], 'readonly');
    const store = transaction.objectStore('projects');
    const request = store.get(projectId);

    request.onsuccess = () => resolve(request.result || null);
    request.onerror = () => reject(request.error);
  });
}

/**
 * Delete project from IndexedDB
 */
export async function deleteProject(projectId: string): Promise<void> {
  const db = await initDB();

  return new Promise((resolve, reject) => {
    const transaction = db.transaction(['projects'], 'readwrite');
    const store = transaction.objectStore('projects');
    const request = store.delete(projectId);

    request.onsuccess = () => resolve();
    request.onerror = () => reject(request.error);
  });
}

/**
 * Serialize AudioBuffer for storage
 */
export function serializeAudioBuffer(buffer: AudioBuffer): SerializedAudioBuffer {
  const channelData: Float32Array[] = [];

  for (let i = 0; i < buffer.numberOfChannels; i++) {
    channelData.push(new Float32Array(buffer.getChannelData(i)));
  }

  return {
    sampleRate: buffer.sampleRate,
    length: buffer.length,
    numberOfChannels: buffer.numberOfChannels,
    channelData,
  };
}

/**
 * Deserialize AudioBuffer from storage
 */
export function deserializeAudioBuffer(
  serialized: SerializedAudioBuffer,
  audioContext: AudioContext
): AudioBuffer {
  const buffer = audioContext.createBuffer(
    serialized.numberOfChannels,
    serialized.length,
    serialized.sampleRate
  );

  for (let i = 0; i < serialized.numberOfChannels; i++) {
    buffer.copyToChannel(new Float32Array(serialized.channelData[i]), i);
  }

  return buffer;
}