// ==UserScript==
// @name        Precise video playback (Bilibili)
// @name:zh-CN  精确控制视频播放进度 (Bilibili)
// @description A toolbar to set precise video play time and generate clip script
// @description:zh-CN 精确控制视频播放进度/生成剪辑脚本的工具栏
// @namespace   moe.suisei.pvp.bilibili
// @match       https://bilibili.com/video/*
// @match       https://www.bilibili.com/video/*
// @grant       none
// @version     0.5.8
// @author      Outvi V
// @downloadURL none
// ==/UserScript==

'use strict'

console.log('Precise Video Playback is up')

function getVideoId(url) {
  return String(url).match(/(a|b)v([^?&#]+)/i)[0]
}

function applyStyle(elem, styles) {
  for (const [key, value] of Object.entries(styles)) {
    elem.style[key] = value
  }
}

function parseTime(str) {
  if (!isNaN(Number(str))) return Number(str)
  let time = str.match(/([0-9]?)?:([0-9]+)(\.([0-9]+))?/)
  if (time === null) return -1
  let ret =
    Number(time[1] || 0) * 60 + Number(time[2]) + Number(time[4] || 0) * 0.1
  if (ret == NaN) return -1
  return ret
}

function generateControl() {
  let app = document.createElement('div')
  let inputFrom = document.createElement('input')
  inputFrom.placeholder = 'from time'
  let inputTo = document.createElement('input')
  inputTo.placeholder = 'to time'
  let currentTime = document.createElement('span')
  let btn = document.createElement('button')
  let btnStop = document.createElement('button')
  let btnExport = document.createElement('button')
  applyStyle(app, {
    display: 'flex',
    alignItems: 'center',
    justifyContent: 'space-between',
    maxWidth: '600px',
    marginTop: '15px',
    marginLeft: 'auto',
    marginRight: 'auto',
  })
  applyStyle(currentTime, {
    fontSize: '1.2rem',
    minWidth: '7.5rem',
    textAlign: 'center',
  })
  let inputCommonStyle = {
    width: '80px',
  }
  applyStyle(inputFrom, inputCommonStyle)
  applyStyle(inputTo, inputCommonStyle)
  btn.innerText = 'Repeat play'
  btnStop.innerText = 'Stop'
  btnExport.innerText = 'Export'
  app.appendChild(inputFrom)
  app.appendChild(inputTo)
  app.appendChild(currentTime)
  app.appendChild(btn)
  app.appendChild(btnStop)
  app.appendChild(btnExport)
  return {
    app,
    inputFrom,
    inputTo,
    currentTime,
    btn,
    btnStop,
    btnExport,
  }
}

async function sleep(time) {
  await new Promise((resolve) => {
    setTimeout(() => {
      resolve()
    }, time)
  })
}

async function waitfor(cb) {
  while (true) {
    if (cb()) return
    await sleep(500)
  }
}

async function main() {
  console.log('Waiting for the page...')
  // Wait for Bilibili to fully render the page
  // Or error could occur after inserting our widget

  await waitfor(() => {
    return (
      document.querySelector('#v_upinfo .up-face') ||
      document.querySelector('#member-container .avatar')
    )
  })
  console.log('Pre-install hook OK')

  // Player fetching
  console.log('Waiting for the player...')
  let anchor
  while (true) {
    anchor = document.querySelector('#v_desc')
    if (anchor && !anchor.hidden) break
    await sleep(500)
  }
  let videoElement = document.querySelector('video')
  if (!videoElement || !anchor) {
    console.warn('Player not found. Exiting.')
    return
  }
  console.log('Player detected.')

  // Layout
  let control = generateControl()
  let shadowParent = document.createElement('div')
  let shadow = shadowParent.attachShadow({ mode: 'open' })
  anchor.parentElement.insertBefore(shadowParent, anchor)
  shadow.appendChild(control.app)

  // States
  let fromValue = 0,
    toValue = 0

  // Initial state update attempt
  let urlTime = window.location.hash.match(
    /#pvp([0-9]+\.?[0-9]?)-([0-9]+\.?[0-9]?)/
  )
  if (urlTime !== null) {
    console.log('Attempting to recover time from URL...')
    control.inputFrom.value = fromValue = Number(urlTime[1]) || 0
    control.inputTo.value = toValue = Number(urlTime[2]) || 0
  }

  // Current playback time
  function updateCurrentTime() {
    control.currentTime.innerText = Number(videoElement.currentTime).toFixed(2)
    requestAnimationFrame(updateCurrentTime)
  }
  requestAnimationFrame(updateCurrentTime)

  // Repeat playback
  function onTimeUpdate() {
    if (videoElement.currentTime >= Number(toValue)) {
      videoElement.currentTime = Number(fromValue)
    }
  }
  control.btn.addEventListener('click', (evt) => {
    evt.preventDefault()
    videoElement.pause()
    videoElement.currentTime = fromValue
    if (fromValue < toValue) {
      videoElement.play()
      videoElement.addEventListener('timeupdate', onTimeUpdate)
    } else {
      videoElement.removeEventListener('timeupdate', onTimeUpdate)
    }
  })
  control.btnStop.addEventListener('click', (evt) => {
    evt.preventDefault()
    videoElement.removeEventListener('timeupdate', onTimeUpdate)
    videoElement.pause()
  })

  // Start/end time setting
  function updateURL() {
    history.pushState(null, null, `#pvp${fromValue}-${toValue}`)
  }
  control.inputFrom.addEventListener('change', () => {
    let input = control.inputFrom.value
    if (input === '') {
      fromValue = 0
      control.inputFrom.placeholder = 'from 0'
      return
    }
    let time = parseTime(input)
    if (time == -1) {
      control.btn.disabled = true
      return
    }
    control.btn.disabled = false
    fromValue = time
    updateURL()
  })
  control.inputTo.addEventListener('change', () => {
    let input = control.inputTo.value
    if (input === '') {
      toValue = videoElement.duration || 0
      control.inputTo.placeholder = `to ${toValue.toFixed(2)}`
      return
    }
    let time = parseTime(input)
    if (time == -1) {
      control.btn.disabled = true
      return
    }
    control.btn.disabled = false
    toValue = time
    updateURL()
  })

  // Button export
  control.btnExport.addEventListener('click', (evt) => {
    evt.preventDefault()
    let videoId = getVideoId(window.location)
    alert(`ykdl https://www.bilibili.com/video/${videoId} -O output-${videoId} &&
    ffmpeg -i output-${videoId}.flv \
-ss ${fromValue} \
-to ${toValue} \
-acodec libmp3lame \
-ab 192k \
-af loudnorm=I=-16:TP=-2:LRA=11 \
-vn \
output-${videoId}-${fromValue}-${toValue}.mp3 && rm output-${videoId}.flv`)
  })
}

main()