lx-music-desktop/src/renderer/utils/lyric-font-player/line-player.js

const { getNow, TimeoutTools } = require('./utils')

const timeExp = /^\[([\d:.]*)\]{1}/g
const tagRegMap = {
  title: 'ti',
  artist: 'ar',
  album: 'al',
  offset: 'offset',
  by: 'by',
}

const timeoutTools = new TimeoutTools()

module.exports = class LinePlayer {
  constructor({ lyric = '', offset = 0, onPlay = function() { }, onSetLyric = function() { } } = {}) {
    this.lyric = lyric
    this.tags = {}
    this.lines = null
    this.onPlay = onPlay
    this.onSetLyric = onSetLyric
    this.isPlay = false
    this.curLineNum = 0
    this.maxLine = 0
    this.offset = offset
    this.isOffseted = false
    this._performanceTime = 0
    this._performanceOffsetTime = 0
    this._init()
  }

  _init() {
    if (this.lyric == null) this.lyric = ''
    this._initTag()
    this._initLines()
    this.onSetLyric(this.lines)
  }

  _initTag() {
    for (let tag in tagRegMap) {
      const matches = this.lyric.match(new RegExp(`\\[${tagRegMap[tag]}:([^\\]]*)]`, 'i'))
      this.tags[tag] = (matches && matches[1]) || ''
    }
  }

  _initLines() {
    this.lines = []
    const lines = this.lyric.split('\n')
    for (let i = 0; i < lines.length; i++) {
      const line = lines[i].trim()
      let result = timeExp.exec(line)
      if (result) {
        const text = line.replace(timeExp, '').trim()
        if (text) {
          const timeArr = RegExp.$1.split(':')
          if (timeArr.length < 3) timeArr.unshift(0)
          if (timeArr[2].indexOf('.') > -1) {
            timeArr.push(...timeArr[2].split('.'))
            timeArr.splice(2, 1)
          }
          this.lines.push({
            time: parseInt(timeArr[0]) * 60 * 60 * 1000 + parseInt(timeArr[1]) * 60 * 1000 + parseInt(timeArr[2]) * 1000 + parseInt(timeArr[3] || 0),
            text,
          })
        }
      }
    }
    this.lines.sort((a, b) => {
      return a.time - b.time
    })
    this.maxLine = this.lines.length - 1
  }

  _currentTime() {
    return getNow() - this._performanceTime + this._performanceOffsetTime
  }

  _findCurLineNum(curTime) {
    const length = this.lines.length
    for (let index = 0; index < length; index++) if (curTime <= this.lines[index].time) return index === 0 ? 0 : index - 1
    return length - 1
  }

  _handleMaxLine() {
    this.onPlay(this.curLineNum, this.lines[this.curLineNum].text, this._currentTime())
    this.pause()
  }

  _refresh() {
    this.curLineNum++
    // console.log('curLineNum time', this.lines[this.curLineNum].time)
    let curLine = this.lines[this.curLineNum]
    let nextLine = this.lines[this.curLineNum + 1]
    const currentTime = this._currentTime()
    const driftTime = currentTime - curLine.time

    if (driftTime >= 0 || this.curLineNum === 0) {
      if (this.curLineNum === this.maxLine) return this._handleMaxLine()
      this.delay = nextLine.time - curLine.time - driftTime
      if (this.delay > 0) {
        if (!this.isOffseted && this.delay >= this.offset) {
          this._performanceOffsetTime += this.offset
          this.delay -= this.offset
          this.isOffseted = true
        }
        timeoutTools.start(() => {
          this._refresh()
        }, this.delay)
        this.onPlay(this.curLineNum, curLine.text, currentTime)
        return
      }
    }

    this.curLineNum = this._findCurLineNum(currentTime) - 1
    this._refresh()
  }

  play(curTime = 0) {
    if (!this.lines.length) return
    this.pause()
    this.isPlay = true

    this._performanceOffsetTime = 0
    this._performanceTime = getNow() - curTime
    if (this._performanceTime < 0) {
      this._performanceOffsetTime = -this._performanceTime
      this._performanceTime = 0
    }

    this.curLineNum = this._findCurLineNum(curTime) - 1

    this._refresh()
  }

  pause() {
    if (!this.isPlay) return
    this.isPlay = false
    this.isOffseted = false
    timeoutTools.clear()
    if (this.curLineNum === this.maxLine) return
    const currentTime = this._currentTime()
    const curLineNum = this._findCurLineNum(currentTime)
    if (this.curLineNum !== curLineNum) {
      this.curLineNum = curLineNum
      this.onPlay(curLineNum, this.lines[curLineNum].text, currentTime)
    }
  }

  setLyric(lyric) {
    if (this.isPlay) this.pause()
    this.lyric = lyric
    this._init()
  }
}