migrate current plugins to ccxt

lib/plugins/common/cctx.js

@@ -0,0 +1,28 @@
+const _ = require('lodash/fp')
+
+const CRYPTO = {
+  bitstamp: ['BTC', 'ETH', 'LTC', 'BCH'],
+  itbit: ['BTC', 'ETH', 'LTC', 'BCH'],
+  kraken: ['BTC', 'ETH', 'LTC', 'DASH', 'ZEC', 'BCH'],
+  coinbase: ['BTC', 'ETH', 'LTC', 'BCH', 'ZEC', 'DASH']
+}
+
+const FIAT = {
+  bitstamp: ['USD', 'EUR'],
+  itbit: ['USD'],
+  kraken: ['USD', 'EUR']
+}
+
+module.exports = { verifyCurrencies }
+
+function verifyCurrencies (exchangeName, fiatCode, cryptoCode) {
+  if (!_.includes(cryptoCode, CRYPTO[exchangeName])) {
+    throw new Error('Unsupported crypto: ' + cryptoCode)
+  }
+  if (!(exchangeName === 'coinbase')) { // coinbase is only used for ticker and it's expected to support most of the fiat
+    if (!_.includes(fiatCode, FIAT[exchangeName])) {
+      throw new Error('Unsupported fiat: ' + fiatCode)
+    }
+  }
+  return cryptoCode + '/' + fiatCode
+}