TTMusic/entry/src/main/ets/playback/PlaybackSnapshotStore.ets

import { PreferencesUtil } from '@pura/harmony-utils'
import { VideoItem } from '../viewmodel/VideoItem'
import { PlaybackSnapshot, PlaybackSnapshotSong } from './model/PlaybackSnapshot'

export const PLAYBACK_SNAPSHOT_PREFERENCES_KEY = 'playback.host.snapshot'

export interface RecoveredPlaybackSnapshotState {
  queue: VideoItem[]
  currentIndex: number
  currentSong: VideoItem | undefined
}

export class PlaybackSnapshotStore {
  public write(snapshot: PlaybackSnapshot): void {
    PreferencesUtil.putSync(PLAYBACK_SNAPSHOT_PREFERENCES_KEY, JSON.stringify(snapshot))
  }

  public read(): PlaybackSnapshot | undefined {
    const text = PreferencesUtil.getStringSync(PLAYBACK_SNAPSHOT_PREFERENCES_KEY, '')
    if (text.length === 0) {
      return undefined
    }
    try {
      const parsedSnapshot = JSON.parse(text) as Object | null
      if (!this.isValidSnapshot(parsedSnapshot)) {
        this.clear()
        return undefined
      }
      return parsedSnapshot
    } catch (_error) {
      this.clear()
      return undefined
    }
  }

  public clear(): void {
    PreferencesUtil.putSync(PLAYBACK_SNAPSHOT_PREFERENCES_KEY, '')
  }

  public restoreQueue(snapshot: PlaybackSnapshot): VideoItem[] {
    return this.recoverQueueState(snapshot).queue
  }

  public restoreCurrentSong(snapshot: PlaybackSnapshot): VideoItem | undefined {
    return this.recoverQueueState(snapshot).currentSong
  }

  public recoverQueueState(snapshot: PlaybackSnapshot): RecoveredPlaybackSnapshotState {
    const snapshotQueue = Array.isArray(snapshot.queue) ? snapshot.queue : []
    const queue: VideoItem[] = []
    for (let index = 0; index < snapshotQueue.length; index++) {
      const snapshotSong = snapshotQueue[index] as Object | null
      if (!this.isValidSnapshotSong(snapshotSong)) {
        continue
      }
      queue.push(this.buildVideoItem(snapshotSong))
    }
    const currentIndex = this.resolveCurrentIndex(snapshot, queue)
    const currentSong = currentIndex >= 0 ? queue[currentIndex] : undefined
    return {
      queue,
      currentIndex,
      currentSong
    }
  }

  private resolveCurrentIndex(snapshot: PlaybackSnapshot, queue: VideoItem[]): number {
    if (queue.length <= 0) {
      return -1
    }
    if (snapshot.currentSongKey && snapshot.currentSongKey !== '') {
      const matchedIndex = queue.findIndex((item: VideoItem): boolean => item.filePath === snapshot.currentSongKey)
      if (matchedIndex >= 0) {
        return matchedIndex
      }
    }
    const requestedIndex = typeof snapshot.currentIndex === 'number' ? snapshot.currentIndex : 0
    return Math.max(0, Math.min(requestedIndex, queue.length - 1))
  }

  private isValidSnapshot(snapshot: Object | null): snapshot is PlaybackSnapshot {
    if (!snapshot || Array.isArray(snapshot)) {
      return false
    }
    const candidate = snapshot as PlaybackSnapshot
    return Array.isArray(candidate.queue) &&
      typeof candidate.currentIndex === 'number' &&
      typeof candidate.currentSongKey === 'string' &&
      typeof candidate.currentSongName === 'string' &&
      typeof candidate.isPlaying === 'boolean' &&
      typeof candidate.positionMs === 'number' &&
      typeof candidate.durationMs === 'number' &&
      typeof candidate.playType === 'number' &&
      typeof candidate.playlistContext === 'string' &&
      typeof candidate.updatedAt === 'number' &&
      typeof candidate.shouldResumeWhenActivated === 'boolean'
  }

  private isValidSnapshotSong(snapshotSong: Object | null): snapshotSong is PlaybackSnapshotSong {
    if (!snapshotSong || Array.isArray(snapshotSong)) {
      return false
    }
    const candidate = snapshotSong as PlaybackSnapshotSong
    return typeof candidate.filePath === 'string' &&
      typeof candidate.name === 'string' &&
      typeof candidate.type === 'number'
  }

  private buildVideoItem(song: PlaybackSnapshotSong): VideoItem {
    const item = new VideoItem(song.name, song.id ?? '', song.filePath, song.type, 0, '')
    item.artist = song.artist
    item.album = song.album
    item.duration = song.duration
    item.pixelMapPath = song.pixelMapPath
    item.lyricContent = song.lyricContent
    item.remote_rel_path = song.remote_rel_path
    item.webdav_account_id = song.webdav_account_id
    return item
  }
}