metamask-extension/ui/app/ducks/gas/gas.duck.js

import { uniqBy, cloneDeep, flatten } from 'lodash'
import BigNumber from 'bignumber.js'
import { getStorageItem, setStorageItem } from '../../../lib/storage-helpers'

import { decGWEIToHexWEI } from '../../helpers/utils/conversions.util'
import { isEthereumNetwork } from '../../selectors'

// Actions
const BASIC_GAS_ESTIMATE_LOADING_FINISHED =
  'metamask/gas/BASIC_GAS_ESTIMATE_LOADING_FINISHED'
const BASIC_GAS_ESTIMATE_LOADING_STARTED =
  'metamask/gas/BASIC_GAS_ESTIMATE_LOADING_STARTED'
const GAS_ESTIMATE_LOADING_FINISHED =
  'metamask/gas/GAS_ESTIMATE_LOADING_FINISHED'
const GAS_ESTIMATE_LOADING_STARTED = 'metamask/gas/GAS_ESTIMATE_LOADING_STARTED'
const RESET_CUSTOM_GAS_STATE = 'metamask/gas/RESET_CUSTOM_GAS_STATE'
const RESET_CUSTOM_DATA = 'metamask/gas/RESET_CUSTOM_DATA'
const SET_BASIC_GAS_ESTIMATE_DATA = 'metamask/gas/SET_BASIC_GAS_ESTIMATE_DATA'
const SET_CUSTOM_GAS_ERRORS = 'metamask/gas/SET_CUSTOM_GAS_ERRORS'
const SET_CUSTOM_GAS_LIMIT = 'metamask/gas/SET_CUSTOM_GAS_LIMIT'
const SET_CUSTOM_GAS_PRICE = 'metamask/gas/SET_CUSTOM_GAS_PRICE'
const SET_CUSTOM_GAS_TOTAL = 'metamask/gas/SET_CUSTOM_GAS_TOTAL'
const SET_PRICE_AND_TIME_ESTIMATES = 'metamask/gas/SET_PRICE_AND_TIME_ESTIMATES'
const SET_API_ESTIMATES_LAST_RETRIEVED =
  'metamask/gas/SET_API_ESTIMATES_LAST_RETRIEVED'
const SET_BASIC_API_ESTIMATES_LAST_RETRIEVED =
  'metamask/gas/SET_BASIC_API_ESTIMATES_LAST_RETRIEVED'
const SET_BASIC_PRICE_ESTIMATES_LAST_RETRIEVED =
  'metamask/gas/SET_BASIC_PRICE_ESTIMATES_LAST_RETRIEVED'

const initState = {
  customData: {
    price: null,
    limit: null,
  },
  basicEstimates: {
    average: null,
    fastestWait: null,
    fastWait: null,
    fast: null,
    safeLowWait: null,
    blockNum: null,
    avgWait: null,
    blockTime: null,
    speed: null,
    fastest: null,
    safeLow: null,
  },
  basicEstimateIsLoading: true,
  gasEstimatesLoading: true,
  priceAndTimeEstimates: [],
  priceAndTimeEstimatesLastRetrieved: 0,
  basicPriceAndTimeEstimatesLastRetrieved: 0,
  basicPriceEstimatesLastRetrieved: 0,
  errors: {},
}

// Reducer
export default function reducer(state = initState, action) {
  switch (action.type) {
    case BASIC_GAS_ESTIMATE_LOADING_STARTED:
      return {
        ...state,
        basicEstimateIsLoading: true,
      }
    case BASIC_GAS_ESTIMATE_LOADING_FINISHED:
      return {
        ...state,
        basicEstimateIsLoading: false,
      }
    case GAS_ESTIMATE_LOADING_STARTED:
      return {
        ...state,
        gasEstimatesLoading: true,
      }
    case GAS_ESTIMATE_LOADING_FINISHED:
      return {
        ...state,
        gasEstimatesLoading: false,
      }
    case SET_BASIC_GAS_ESTIMATE_DATA:
      return {
        ...state,
        basicEstimates: action.value,
      }
    case SET_CUSTOM_GAS_PRICE:
      return {
        ...state,
        customData: {
          ...state.customData,
          price: action.value,
        },
      }
    case SET_CUSTOM_GAS_LIMIT:
      return {
        ...state,
        customData: {
          ...state.customData,
          limit: action.value,
        },
      }
    case SET_CUSTOM_GAS_TOTAL:
      return {
        ...state,
        customData: {
          ...state.customData,
          total: action.value,
        },
      }
    case SET_PRICE_AND_TIME_ESTIMATES:
      return {
        ...state,
        priceAndTimeEstimates: action.value,
      }
    case SET_CUSTOM_GAS_ERRORS:
      return {
        ...state,
        errors: {
          ...state.errors,
          ...action.value,
        },
      }
    case SET_API_ESTIMATES_LAST_RETRIEVED:
      return {
        ...state,
        priceAndTimeEstimatesLastRetrieved: action.value,
      }
    case SET_BASIC_API_ESTIMATES_LAST_RETRIEVED:
      return {
        ...state,
        basicPriceAndTimeEstimatesLastRetrieved: action.value,
      }
    case SET_BASIC_PRICE_ESTIMATES_LAST_RETRIEVED:
      return {
        ...state,
        basicPriceEstimatesLastRetrieved: action.value,
      }
    case RESET_CUSTOM_DATA:
      return {
        ...state,
        customData: cloneDeep(initState.customData),
      }
    case RESET_CUSTOM_GAS_STATE:
      return cloneDeep(initState)
    default:
      return state
  }
}

// Action Creators
export function basicGasEstimatesLoadingStarted() {
  return {
    type: BASIC_GAS_ESTIMATE_LOADING_STARTED,
  }
}

export function basicGasEstimatesLoadingFinished() {
  return {
    type: BASIC_GAS_ESTIMATE_LOADING_FINISHED,
  }
}

export function gasEstimatesLoadingStarted() {
  return {
    type: GAS_ESTIMATE_LOADING_STARTED,
  }
}

export function gasEstimatesLoadingFinished() {
  return {
    type: GAS_ESTIMATE_LOADING_FINISHED,
  }
}

async function queryEthGasStationBasic() {
  const apiKey = process.env.ETH_GAS_STATION_API_KEY
    ? `?api-key=${process.env.ETH_GAS_STATION_API_KEY}`
    : ''
  const url = `https://ethgasstation.info/json/ethgasAPI.json${apiKey}`
  return await window.fetch(url, {
    headers: {},
    referrer: 'http://ethgasstation.info/json/',
    referrerPolicy: 'no-referrer-when-downgrade',
    body: null,
    method: 'GET',
    mode: 'cors',
  })
}

async function queryEthGasStationPredictionTable() {
  const apiKey = process.env.ETH_GAS_STATION_API_KEY
    ? `?api-key=${process.env.ETH_GAS_STATION_API_KEY}`
    : ''
  const url = `https://ethgasstation.info/json/predictTable.json${apiKey}`
  return await window.fetch(url, {
    headers: {},
    referrer: 'http://ethgasstation.info/json/',
    referrerPolicy: 'no-referrer-when-downgrade',
    body: null,
    method: 'GET',
    mode: 'cors',
  })
}

export function fetchBasicGasEstimates() {
  return async (dispatch, getState) => {
    const { basicPriceEstimatesLastRetrieved } = getState().gas
    const timeLastRetrieved =
      basicPriceEstimatesLastRetrieved ||
      (await getStorageItem('BASIC_PRICE_ESTIMATES_LAST_RETRIEVED')) ||
      0

    dispatch(basicGasEstimatesLoadingStarted())

    let basicEstimates
    if (Date.now() - timeLastRetrieved > 75000) {
      basicEstimates = await fetchExternalBasicGasEstimates(dispatch)
    } else {
      const cachedBasicEstimates = await getStorageItem('BASIC_PRICE_ESTIMATES')
      basicEstimates =
        cachedBasicEstimates || (await fetchExternalBasicGasEstimates(dispatch))
    }

    dispatch(setBasicGasEstimateData(basicEstimates))
    dispatch(basicGasEstimatesLoadingFinished())

    return basicEstimates
  }
}

async function fetchExternalBasicGasEstimates(dispatch) {
  const response = await queryEthGasStationBasic()

  const {
    safeLow: safeLowTimes10,
    average: averageTimes10,
    fast: fastTimes10,
    fastest: fastestTimes10,
    block_time: blockTime,
    blockNum,
  } = await response.json()

  const [average, fast, fastest, safeLow] = [
    averageTimes10,
    fastTimes10,
    fastestTimes10,
    safeLowTimes10,
  ].map((price) => new BigNumber(price).div(10).toNumber())

  const basicEstimates = {
    safeLow,
    average,
    fast,
    fastest,
    blockTime,
    blockNum,
  }

  const timeRetrieved = Date.now()
  await Promise.all([
    setStorageItem('BASIC_PRICE_ESTIMATES', basicEstimates),
    setStorageItem('BASIC_PRICE_ESTIMATES_LAST_RETRIEVED', timeRetrieved),
  ])
  dispatch(setBasicPriceEstimatesLastRetrieved(timeRetrieved))

  return basicEstimates
}

export function fetchBasicGasAndTimeEstimates() {
  return async (dispatch, getState) => {
    const { basicPriceAndTimeEstimatesLastRetrieved } = getState().gas
    const timeLastRetrieved =
      basicPriceAndTimeEstimatesLastRetrieved ||
      (await getStorageItem(
        'BASIC_GAS_AND_TIME_API_ESTIMATES_LAST_RETRIEVED',
      )) ||
      0

    dispatch(basicGasEstimatesLoadingStarted())

    let basicEstimates
    if (Date.now() - timeLastRetrieved > 75000) {
      basicEstimates = await fetchExternalBasicGasAndTimeEstimates(dispatch)
    } else {
      const cachedBasicEstimates = await getStorageItem(
        'BASIC_GAS_AND_TIME_API_ESTIMATES',
      )
      basicEstimates =
        cachedBasicEstimates ||
        (await fetchExternalBasicGasAndTimeEstimates(dispatch))
    }

    dispatch(setBasicGasEstimateData(basicEstimates))
    dispatch(basicGasEstimatesLoadingFinished())
    return basicEstimates
  }
}

async function fetchExternalBasicGasAndTimeEstimates(dispatch) {
  const response = await queryEthGasStationBasic()

  const {
    average: averageTimes10,
    avgWait,
    block_time: blockTime,
    blockNum,
    fast: fastTimes10,
    fastest: fastestTimes10,
    fastestWait,
    fastWait,
    safeLow: safeLowTimes10,
    safeLowWait,
    speed,
  } = await response.json()
  const [average, fast, fastest, safeLow] = [
    averageTimes10,
    fastTimes10,
    fastestTimes10,
    safeLowTimes10,
  ].map((price) => new BigNumber(price).div(10).toNumber())

  const basicEstimates = {
    average,
    avgWait,
    blockTime,
    blockNum,
    fast,
    fastest,
    fastestWait,
    fastWait,
    safeLow,
    safeLowWait,
    speed,
  }

  const timeRetrieved = Date.now()
  await Promise.all([
    setStorageItem('BASIC_GAS_AND_TIME_API_ESTIMATES', basicEstimates),
    setStorageItem(
      'BASIC_GAS_AND_TIME_API_ESTIMATES_LAST_RETRIEVED',
      timeRetrieved,
    ),
  ])
  dispatch(setBasicApiEstimatesLastRetrieved(timeRetrieved))

  return basicEstimates
}

function extrapolateY({ higherY, lowerY, higherX, lowerX, xForExtrapolation }) {
  /* eslint-disable no-param-reassign */
  higherY = new BigNumber(higherY, 10)
  lowerY = new BigNumber(lowerY, 10)
  higherX = new BigNumber(higherX, 10)
  lowerX = new BigNumber(lowerX, 10)
  xForExtrapolation = new BigNumber(xForExtrapolation, 10)
  /* eslint-enable no-param-reassign */
  const slope = higherY.minus(lowerY).div(higherX.minus(lowerX))
  const newTimeEstimate = slope
    .times(higherX.minus(xForExtrapolation))
    .minus(higherY)
    .negated()

  return Number(newTimeEstimate.toPrecision(10))
}

function getRandomArbitrary(minStr, maxStr) {
  const min = new BigNumber(minStr, 10)
  const max = new BigNumber(maxStr, 10)
  const random = new BigNumber(String(Math.random()), 10)
  return new BigNumber(random.times(max.minus(min)).plus(min)).toPrecision(10)
}

function calcMedian(list) {
  const medianPos =
    (Math.floor(list.length / 2) + Math.ceil(list.length / 2)) / 2
  return medianPos === Math.floor(medianPos)
    ? (list[medianPos - 1] + list[medianPos]) / 2
    : list[Math.floor(medianPos)]
}

function quartiles(data) {
  const lowerHalf = data.slice(0, Math.floor(data.length / 2))
  const upperHalf = data.slice(
    Math.floor(data.length / 2) + (data.length % 2 === 0 ? 0 : 1),
  )
  const median = calcMedian(data)
  const lowerQuartile = calcMedian(lowerHalf)
  const upperQuartile = calcMedian(upperHalf)
  return {
    median,
    lowerQuartile,
    upperQuartile,
  }
}

function inliersByIQR(data, prop) {
  const { lowerQuartile, upperQuartile } = quartiles(
    data.map((d) => (prop ? d[prop] : d)),
  )
  const IQR = upperQuartile - lowerQuartile
  const lowerBound = lowerQuartile - 1.5 * IQR
  const upperBound = upperQuartile + 1.5 * IQR
  return data.filter((d) => {
    const value = prop ? d[prop] : d
    return value >= lowerBound && value <= upperBound
  })
}

export function fetchGasEstimates(blockTime) {
  return async (dispatch, getState) => {
    const state = getState()

    if (!isEthereumNetwork(state)) {
      return
    }

    const {
      priceAndTimeEstimatesLastRetrieved,
      priceAndTimeEstimates,
    } = state.gas
    const timeLastRetrieved =
      priceAndTimeEstimatesLastRetrieved ||
      (await getStorageItem('GAS_API_ESTIMATES_LAST_RETRIEVED')) ||
      0

    dispatch(gasEstimatesLoadingStarted())

    const shouldGetFreshGasQuote = Date.now() - timeLastRetrieved > 75000
    let estimates
    if (shouldGetFreshGasQuote) {
      const response = await queryEthGasStationPredictionTable()
      const tableJson = await response.json()

      const estimatedPricesAndTimes = tableJson.map(
        ({ expectedTime, expectedWait, gasprice }) => ({
          expectedTime,
          expectedWait,
          gasprice,
        }),
      )
      const estimatedTimeWithUniquePrices = uniqBy(
        estimatedPricesAndTimes,
        ({ expectedTime }) => expectedTime,
      )

      const withSupplementalTimeEstimates = flatten(
        estimatedTimeWithUniquePrices.map(
          ({ expectedWait, gasprice }, i, arr) => {
            const next = arr[i + 1]
            if (!next) {
              return [{ expectedWait, gasprice }]
            }
            const supplementalPrice = getRandomArbitrary(
              gasprice,
              next.gasprice,
            )
            const supplementalTime = extrapolateY({
              higherY: next.expectedWait,
              lowerY: expectedWait,
              higherX: next.gasprice,
              lowerX: gasprice,
              xForExtrapolation: supplementalPrice,
            })
            const supplementalPrice2 = getRandomArbitrary(
              supplementalPrice,
              next.gasprice,
            )
            const supplementalTime2 = extrapolateY({
              higherY: next.expectedWait,
              lowerY: supplementalTime,
              higherX: next.gasprice,
              lowerX: supplementalPrice,
              xForExtrapolation: supplementalPrice2,
            })
            return [
              { expectedWait, gasprice },
              {
                expectedWait: supplementalTime,
                gasprice: supplementalPrice,
              },
              {
                expectedWait: supplementalTime2,
                gasprice: supplementalPrice2,
              },
            ]
          },
        ),
      )
      const withOutliersRemoved = inliersByIQR(
        withSupplementalTimeEstimates.slice(0).reverse(),
        'expectedWait',
      ).reverse()
      const timeMappedToSeconds = withOutliersRemoved.map(
        ({ expectedWait, gasprice }) => {
          const expectedTime = new BigNumber(expectedWait)
            .times(Number(blockTime), 10)
            .toNumber()
          return {
            expectedTime,
            gasprice: new BigNumber(gasprice, 10).toNumber(),
          }
        },
      )

      const timeRetrieved = Date.now()
      dispatch(setApiEstimatesLastRetrieved(timeRetrieved))

      await Promise.all([
        setStorageItem('GAS_API_ESTIMATES_LAST_RETRIEVED', timeRetrieved),
        setStorageItem('GAS_API_ESTIMATES', timeMappedToSeconds),
      ])

      estimates = timeMappedToSeconds
    } else if (priceAndTimeEstimates.length) {
      estimates = priceAndTimeEstimates
    } else {
      estimates = await getStorageItem('GAS_API_ESTIMATES')
    }

    dispatch(setPricesAndTimeEstimates(estimates))
    dispatch(gasEstimatesLoadingFinished())
  }
}

export function setCustomGasPriceForRetry(newPrice) {
  return async (dispatch) => {
    if (newPrice === '0x0') {
      const { fast } = await getStorageItem('BASIC_PRICE_ESTIMATES')
      dispatch(setCustomGasPrice(decGWEIToHexWEI(fast)))
    } else {
      dispatch(setCustomGasPrice(newPrice))
    }
  }
}

export function setBasicGasEstimateData(basicGasEstimateData) {
  return {
    type: SET_BASIC_GAS_ESTIMATE_DATA,
    value: basicGasEstimateData,
  }
}

export function setPricesAndTimeEstimates(estimatedPricesAndTimes) {
  return {
    type: SET_PRICE_AND_TIME_ESTIMATES,
    value: estimatedPricesAndTimes,
  }
}

export function setCustomGasPrice(newPrice) {
  return {
    type: SET_CUSTOM_GAS_PRICE,
    value: newPrice,
  }
}

export function setCustomGasLimit(newLimit) {
  return {
    type: SET_CUSTOM_GAS_LIMIT,
    value: newLimit,
  }
}

export function setCustomGasTotal(newTotal) {
  return {
    type: SET_CUSTOM_GAS_TOTAL,
    value: newTotal,
  }
}

export function setCustomGasErrors(newErrors) {
  return {
    type: SET_CUSTOM_GAS_ERRORS,
    value: newErrors,
  }
}

export function setApiEstimatesLastRetrieved(retrievalTime) {
  return {
    type: SET_API_ESTIMATES_LAST_RETRIEVED,
    value: retrievalTime,
  }
}

export function setBasicApiEstimatesLastRetrieved(retrievalTime) {
  return {
    type: SET_BASIC_API_ESTIMATES_LAST_RETRIEVED,
    value: retrievalTime,
  }
}

export function setBasicPriceEstimatesLastRetrieved(retrievalTime) {
  return {
    type: SET_BASIC_PRICE_ESTIMATES_LAST_RETRIEVED,
    value: retrievalTime,
  }
}

export function resetCustomGasState() {
  return { type: RESET_CUSTOM_GAS_STATE }
}

export function resetCustomData() {
  return { type: RESET_CUSTOM_DATA }
}