function padEnd(str, targetLength, padString) {
  if (str.length > targetLength) {
    return String(str)
  }
  else {
    targetLength = targetLength - str.length
    if (targetLength > padString.length) {
      padString += padString.repeat(targetLength / padString.length)
    }
    return String(str) + padString.slice(0, targetLength)
  }
}

function t2d(time) {
  const arr = time.split('.')
  const left = arr[0].split(':') || []
  const right = padEnd(arr[1] || '0', 3, '0')
  const ms = Number(right) / 1000

  const h = Number(left[left.length - 3] || 0) * 3600
  const m = Number(left[left.length - 2] || 0) * 60
  const s = Number(left[left.length - 1] || 0)
  return h + m + s + ms
}

export default async function getVttArray(vttUrl = '') {
  const vttString = await (await fetch(vttUrl)).text()
  const lines = vttString.split(/[\n\r]/g).filter(item => item.trim())
  const vttArray = []

  for (let i = 1; i < lines.length; i += 2) {
    const time = lines[i]
    const text = lines[i + 1]

    if (!text.trim())
      continue

    const timeReg
      = /((?:\d{2}:)?(?:\d{2}:)?\d{2}(?:.\d{3})?) ?--> ?((?:\d{2}:)?(?:\d{2}:)?\d{2}(?:.\d{3})?)/
    const timeMatch = time.match(timeReg)

    const textReg = /(.*)#(\w{4})=(.*)/
    const textMatch = text.match(textReg)

    const start = Math.floor(t2d(timeMatch[1]))
    const end = Math.floor(t2d(timeMatch[2]))

    let url = textMatch[1]
    const isAbsoluteUrl = /^\/|(?:https?|ftp|file):\/\//i.test(url)
    if (!isAbsoluteUrl) {
      const urlArr = vttUrl.split('/')
      urlArr.pop()
      urlArr.push(url)
      url = urlArr.join('/')
    }

    const result = { start, end, url }

    const keys = textMatch[2].split('')
    const values = textMatch[3].split(',')

    for (let j = 0; j < keys.length; j++) {
      result[keys[j]] = values[j]
    }

    vttArray.push(result)
  }

  return vttArray
}