Refactored some exchange code

lib/plugins/exchange/ccxt.js

@@ -0,0 +1,51 @@
+var ccxt = require('ccxt')
+const coinUtils = require('../../coin-utils')
+const common = require('../common/ccxt')
+const kraken = require('./kraken')
+const bitstamp = require('./bitstamp')
+const itbit = require('./itbit')
+const consts = require('./consts')
+
+const ALL_EXCHANGES = {
+  kraken,
+  bitstamp,
+  itbit
+}
+
+function trade (side, account, cryptoAtoms, fiatCode, cryptoCode, exchangeName) {
+  try {
+    const exchangeConfig = ALL_EXCHANGES[exchangeName]
+
+    if (!exchangeConfig) throw Error('no exchange')
+    if (exchangeConfig.isConfigValid && !exchangeConfig.isConfigValid(account)) throw Error('Invalid config')
+
+    const exchange = new ccxt[exchangeName](exchangeConfig.loadConfig(account))
+
+    const symbol = common.verifyCurrencies(exchangeName, fiatCode, cryptoCode)
+    const precision = exchangeConfig.amountPrecision ? exchangeConfig.amountPrecision() : consts.DECIMAL_PRECISION.DEFAULT_AMOUNT
+    const amount = coinUtils.toUnit(cryptoAtoms, cryptoCode).toFixed(precision)
+    const options = exchangeConfig.loadOptions ? exchangeConfig.loadOptions(account) : {}
+    if (exchangeConfig.ORDER_TYPE === consts.ORDER_TYPES.MARKET) {
+      return exchange.createOrder(symbol, consts.ORDER_TYPES.MARKET, side, amount, null, options)
+    }
+    return exchange.fetchOrderBook(symbol)
+      .then(orderBook => {
+        const price = calculatePrice(side, amount, orderBook).toFixed(consts.DECIMAL_PRECISION.PRICE)
+        return exchange.createOrder(symbol, consts.ORDER_TYPES.LIMIT, side, amount, price, options)
+      })
+  } catch (e) {
+    return Promise.reject(e)
+  }
+}
+
+function calculatePrice (side, amount, orderBook) {
+  const book = side === 'buy' ? 'asks' : 'bids'
+  let collected = 0.0
+  for (const entry of orderBook[book]) {
+    collected += parseFloat(entry[1])
+    if (collected >= amount) return parseFloat(entry[0])
+  }
+  throw new Error('Insufficient market depth')
+}
+
+module.exports = { trade }