/**
 * Media Session API 管理工具
 * 专门处理iOS PWA的锁屏和灵动岛专辑图片显示
 * 
 * 基于2024年最佳实践：
 * - iOS 18修复了低分辨率图片问题，现在使用512x512而不是像素化放大
 * - 提供多尺寸图片以兼容不同设备和显示模式
 * - 使用Canvas优化图片以确保iOS兼容性
 */

class MediaSessionManager {
  constructor() {
    this.isSupported = 'mediaSession' in navigator
    this.currentBlobUrl = null
    this.artworkCache = new Map() // 缓存处理后的图片
    
    // 默认图标路径
    this.defaultArtwork = {
      src: `${import.meta.env.BASE_URL}icons/icon-512x512.svg`,
      sizes: '512x512',
      type: 'image/svg+xml'
    }

    if (this.isSupported) {
      console.log('Media Session API 支持已启用')
      this.setupActionHandlers()
    } else {
      console.log('Media Session API 不支持')
    }
  }

  /**
   * 设置媒体会话信息
   * @param {Object} song - 歌曲信息
   * @param {Object} options - 选项
   * @param {Function} options.onPlay - 播放回调
   * @param {Function} options.onPause - 暂停回调
   * @param {Function} options.onNext - 下一首回调
   * @param {Function} options.onPrev - 上一首回调
   */
  async setMetadata(song, options = {}) {
    if (!this.isSupported || !song) {
      return
    }

    try {
      // 获取优化后的专辑封面
      const artwork = await this.getOptimizedArtwork(song)
      
      // 设置媒体元数据
      navigator.mediaSession.metadata = new MediaMetadata({
        title: song.name || '未知歌曲',
        artist: this.formatArtist(song.artist) || '未知艺术家',
        album: song.album || '未知专辑',
        artwork: artwork
      })

      // 更新动作处理器
      if (options.onPlay) this.onPlayHandler = options.onPlay
      if (options.onPause) this.onPauseHandler = options.onPause  
      if (options.onNext) this.onNextHandler = options.onNext
      if (options.onPrev) this.onPrevHandler = options.onPrev

      console.log('Media Session 元数据已更新:', song.name)
    } catch (error) {
      console.error('设置 Media Session 元数据失败:', error)
    }
  }

  /**
   * 获取优化后的专辑封面
   * 使用Canvas处理以确保iOS兼容性
   */
  async getOptimizedArtwork(song) {
    // 尝试获取真实的专辑封面
    let coverUrl = null
    
    if (song.cover) {
      coverUrl = song.cover
    } else {
      // 尝试从playerStore获取封面
      try {
        const { usePlayerStore } = await import('@/stores/player')
        const playerStore = usePlayerStore()
        coverUrl = await playerStore.getAlbumCover(song, 300)
      } catch (error) {
        console.warn('获取专辑封面失败:', error)
      }
    }

    // 如果有真实封面，创建多尺寸版本
    if (coverUrl && coverUrl !== this.defaultArtwork.src) {
      return await this.createMultiSizeArtwork(coverUrl, song)
    }

    // 返回默认图标
    return [this.defaultArtwork]
  }

  /**
   * 创建多尺寸专辑封面
   * 基于iOS 18的最佳实践
   */
  async createMultiSizeArtwork(imageUrl, song) {
    const cacheKey = `${song.source}-${song.id || song.pic_id}`
    
    // 检查缓存
    if (this.artworkCache.has(cacheKey)) {
      return this.artworkCache.get(cacheKey)
    }

    try {
      const artwork = await this.processImageForMediaSession(imageUrl)
      this.artworkCache.set(cacheKey, artwork)
      return artwork
    } catch (error) {
      console.error('处理专辑封面失败:', error)
      return [this.defaultArtwork]
    }
  }

  /**
   * 使用Canvas处理图片，确保iOS兼容性
   */
  async processImageForMediaSession(imageUrl) {
    return new Promise((resolve, reject) => {
      const image = new Image()
      image.crossOrigin = 'anonymous'
      
      image.onload = async () => {
        try {
          // 创建多个尺寸的Canvas版本
          const sizes = [
            { width: 96, height: 96 },    // 小播放器
            { width: 128, height: 128 },  // 通知
            { width: 192, height: 192 },  // 中等尺寸
            { width: 256, height: 256 },  // 低端设备
            { width: 512, height: 512 }   // 高分辨率，iOS 18推荐
          ]

          const artwork = []

          // 为每个尺寸创建优化的版本
          for (const size of sizes) {
            const canvas = document.createElement('canvas')
            canvas.width = size.width
            canvas.height = size.height
            const ctx = canvas.getContext('2d')
            
            // 使用高质量缩放
            ctx.imageSmoothingEnabled = true
            ctx.imageSmoothingQuality = 'high'
            
            // 绘制图片
            ctx.drawImage(image, 0, 0, size.width, size.height)
            
            // 转换为blob URL
            const blob = await new Promise(resolve => {
              canvas.toBlob(resolve, 'image/png', 0.9)
            })
            
            if (blob) {
              const blobUrl = URL.createObjectURL(blob)
              artwork.push({
                src: blobUrl,
                sizes: `${size.width}x${size.height}`,
                type: 'image/png'
              })
            }
          }

          resolve(artwork)
        } catch (error) {
          reject(error)
        }
      }

      image.onerror = () => {
        reject(new Error('图片加载失败'))
      }

      image.src = imageUrl
    })
  }

  /**
   * 设置播放状态
   */
  setPlaybackState(state) {
    if (!this.isSupported) return

    try {
      navigator.mediaSession.playbackState = state // 'playing', 'paused', 'none'
    } catch (error) {
      console.error('设置播放状态失败:', error)
    }
  }

  /**
   * 设置播放位置信息
   */
  setPositionState(duration, position, playbackRate = 1.0) {
    if (!this.isSupported) return

    try {
      if ('setPositionState' in navigator.mediaSession) {
        navigator.mediaSession.setPositionState({
          duration: duration || 0,
          position: position || 0,
          playbackRate: playbackRate
        })
      }
    } catch (error) {
      console.error('设置播放位置失败:', error)
    }
  }

  /**
   * 设置动作处理器
   */
  setupActionHandlers() {
    if (!this.isSupported) return

    const actions = [
      'play',
      'pause', 
      'previoustrack',
      'nexttrack',
      'seekbackward',
      'seekforward',
      'seekto'
    ]

    actions.forEach(action => {
      try {
        navigator.mediaSession.setActionHandler(action, (details) => {
          this.handleAction(action, details)
        })
      } catch (error) {
        console.warn(`不支持的媒体动作: ${action}`)
      }
    })
  }

  /**
   * 处理媒体控制动作
   */
  handleAction(action, details) {
    console.log('媒体控制动作:', action, details)

    switch (action) {
      case 'play':
        if (this.onPlayHandler) this.onPlayHandler()
        break
      case 'pause':
        if (this.onPauseHandler) this.onPauseHandler()
        break
      case 'previoustrack':
        if (this.onPrevHandler) this.onPrevHandler()
        break
      case 'nexttrack':
        if (this.onNextHandler) this.onNextHandler()
        break
      case 'seekto':
        if (this.onSeekToHandler && details.seekTime !== undefined) {
          this.onSeekToHandler(details.seekTime)
        }
        break
      case 'seekbackward':
        if (this.onSeekBackwardHandler) {
          this.onSeekBackwardHandler(details.seekOffset || 10)
        }
        break
      case 'seekforward':
        if (this.onSeekForwardHandler) {
          this.onSeekForwardHandler(details.seekOffset || 10)
        }
        break
    }
  }

  /**
   * 格式化艺术家名称
   */
  formatArtist(artist) {
    if (!artist) return '未知艺术家'
    if (Array.isArray(artist)) {
      return artist.join(', ')
    }
    if (typeof artist === 'string') {
      return artist.replace(/;|；/g, ', ')
    }
    return String(artist)
  }

  /**
   * 清理资源
   */
  cleanup() {
    // 清理blob URLs
    this.artworkCache.forEach(artwork => {
      artwork.forEach(art => {
        if (art.src && art.src.startsWith('blob:')) {
          URL.revokeObjectURL(art.src)
        }
      })
    })
    this.artworkCache.clear()

    if (this.currentBlobUrl) {
      URL.revokeObjectURL(this.currentBlobUrl)
      this.currentBlobUrl = null
    }
  }

  /**
   * 重置媒体会话
   */
  reset() {
    if (!this.isSupported) return

    try {
      navigator.mediaSession.metadata = null
      navigator.mediaSession.playbackState = 'none'
    } catch (error) {
      console.error('重置媒体会话失败:', error)
    }
  }
}

// 创建单例实例
const mediaSessionManager = new MediaSessionManager()

export default mediaSessionManager
export { MediaSessionManager }