import { VideoItem } from '../../viewmodel/VideoItem'

function normalizeSearchText(value: string | undefined): string {
  return value ? value.trim().toLowerCase() : ''
}

function buildSearchCandidateText(song: VideoItem): string {
  const rawFragments: Array<string | undefined> = [
    song.name,
    song.artist,
    song.album,
    song.fileName
  ]
  const fragments: string[] = []

  rawFragments.forEach((item: string | undefined): void => {
    if (item !== undefined && item.length > 0) {
      fragments.push(item)
    }
  })

  return fragments
    .join('\n')
    .toLowerCase()
}

// 歌单搜索只在当前歌单队列里过滤，保持原始歌单顺序不变。
export function filterPlaylistSongsByKeyword(songs: VideoItem[], keyword: string): VideoItem[] {
  const normalizedKeyword = normalizeSearchText(keyword)
  if (normalizedKeyword.length === 0) {
    return [...songs]
  }

  return songs.filter((song: VideoItem): boolean => {
    return buildSearchCandidateText(song).includes(normalizedKeyword)
  })
}

// 播放队列定位未命中时必须返回 -1，避免错误回落到队列第一首。
export function findSongIndexByFilePath(queue: VideoItem[], filePath: string): number {
  for (let index = 0; index < queue.length; index++) {
    if (queue[index].filePath === filePath) {
      return index
    }
  }
  return -1
}