js/util/eta.js

/**
 * legraphista의 simple-eta를 es module로 사용할 수 있도록 변형한 버전입니다.
 * simple-eta: https://github.com/legraphista/eta
 */

/*
MIT License

Copyright (c) 2018 Ștefan-Gabriel Muscalu

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

function makeLowPassFilter (RC) {
  return function (previousOutput, input, dt) {
    const alpha = dt / (dt + RC)
    return previousOutput + alpha * (input - previousOutput)
  }
}

function def (x, d) {
  return (x === undefined || x === null) ? d : x
}

export default function makeEta (options) {
  options = options || {}
  const max = def(options.max, 1)
  const min = def(options.min, 0)
  const autostart = def(options.autostart, true)
  const ignoreSameProgress = def(options.ignoreSameProgress, false)

  let rate = null
  let lastTimestamp = null
  let lastProgress = null

  const filter = makeLowPassFilter(def(options.historyTimeConstant, 2.5))

  function start () {
    report(min)
  }

  function reset () {
    rate = null
    lastTimestamp = null
    lastProgress = null
    if (autostart) {
      start()
    }
  }

  function report (progress, timestamp) {
    if (typeof timestamp !== 'number') {
      timestamp = Date.now()
    }

    if (lastTimestamp === timestamp) { return }
    if (ignoreSameProgress && lastProgress === progress) { return }

    if (lastTimestamp === null || lastProgress === null) {
      lastProgress = progress
      lastTimestamp = timestamp
      return
    }

    const deltaProgress = progress - lastProgress
    const deltaTimestamp = 0.001 * (timestamp - lastTimestamp)
    const currentRate = deltaProgress / deltaTimestamp

    rate = rate === null
      ? currentRate
      : filter(rate, currentRate, deltaTimestamp)
    lastProgress = progress
    lastTimestamp = timestamp
  }

  function estimate (timestamp) {
    if (lastProgress === null) { return Infinity }
    if (lastProgress >= max) { return 0 }
    if (rate === null) { return Infinity }

    let estimatedTime = (max - lastProgress) / rate
    if (typeof timestamp === 'number' && typeof lastTimestamp === 'number') {
      estimatedTime -= (timestamp - lastTimestamp) * 0.001
    }
    return Math.max(0, estimatedTime)
  }

  function getRate () {
    return rate === null ? 0 : rate
  }

  return {
    start: start,
    reset: reset,
    report: report,
    estimate: estimate,
    rate: getRate
  }
}