const { utils: coinUtils } = require('@lamassu/coins')
const _ = require('lodash/fp')
const mem = require('mem')

const configManager = require('./new-config-manager')
const logger = require('./logger')
const lastRate = {}

const ccxt = require('./plugins/ticker/ccxt')
const mockTicker = require('./plugins/ticker/mock-ticker')
const bitpay = require('./plugins/ticker/bitpay')

const FETCH_INTERVAL = 58000

const PEGGED_FIAT_CURRENCIES = { NAD: 'ZAR' }

const getFallbackTicker = ticker =>
  _.difference(['bitpay', 'kraken', 'bitstamp'], [ticker])[0]

const hasRatesOrReject = emsg => r =>
  _.get(['rates'], r) ? r : Promise.reject(new Error(emsg))

const get1 = (market, fiatCode, cryptoCode, ticker, emsg) =>
  buildTicker(fiatCode, cryptoCode, ticker)
    .then(hasRatesOrReject(emsg))
    .then(({ rates }) => {
      return (lastRate[market] = { rates, timestamp: Date.now() })
    })

const _getRates = (settings, fiatCode, cryptoCode) =>
  Promise.resolve().then(() => {
    const ticker = configManager.getWalletSettings(
      cryptoCode,
      settings.config,
    ).ticker
    const market = [cryptoCode, fiatCode].join('-')
    const fallbackTicker = getFallbackTicker(ticker)
    const emsg = fallbackTicker
      ? 'Failed to get rates with configured ticker, trying fallback'
      : 'Failed to get ticker rates'
    return get1(market, fiatCode, cryptoCode, ticker, emsg)
      .catch(err => {
        logger.error(err)
        return fallbackTicker
          ? get1(
              market,
              fiatCode,
              cryptoCode,
              fallbackTicker,
              'Failed to get rates with fallback ticker',
            )
          : lastRate[market]
      })
      .then(hasRatesOrReject('Failed to get ticker rates'))
  })

function buildTicker(fiatCode, cryptoCode, tickerName) {
  fiatCode = _.defaultTo(fiatCode, _.get([fiatCode], PEGGED_FIAT_CURRENCIES))
  cryptoCode = coinUtils.getEquivalentCode(cryptoCode)

  if (tickerName === 'bitpay') return bitpay.ticker(fiatCode, cryptoCode)
  if (tickerName === 'mock-ticker')
    return mockTicker.ticker(fiatCode, cryptoCode)
  return ccxt.ticker(fiatCode, cryptoCode, tickerName)
}

const getRates = mem(_getRates, {
  maxAge: FETCH_INTERVAL,
  cacheKey: (settings, fiatCode, cryptoCode) =>
    JSON.stringify([fiatCode, cryptoCode]),
})

module.exports = { getRates }