Add estimateSendcurrencyFee API implementation

routes/api.js

@@ -147,6 +147,7 @@ api = require('./api/native/idUpdate.js')(api);
 api = require('./api/native/idInformation.js')(api);
 api = require('./api/native/getCurrencies.js')(api);
 api = require('./api/native/getCurrency.js')(api);
+api = require('./api/native/estimateSendcurrencyFee.js')(api);
 api = require('./api/native/estimateConversion.js')(api);
 api = require('./api/native/getConversionPaths.js')(api);
 api = require('./api/native/currencyGraylist.js')(api);

routes/api/native/estimateSendcurrencyFee.js

@@ -0,0 +1,53 @@
+module.exports = (api) => {
+  api.native.estimate_sendcurrency_fee = async (chain, _params, minconfs = 1, sendfee = 0.0001) => {
+    try {
+      let feecurrency;
+
+      const vETH = await api.native.get_currency(chain, 'vETH');
+
+      // These are throwaway addresses, without any funds, to ensure this 
+      // tx would fail if it were to be broadcasted, or at least not spend 
+      // any user funds in the absolute worst case scenario.
+      const raddr = "RGM3raQ1McqQYZpFyuBrqUpLnmgK7h8k4A"
+      const address = _params.exportto === vETH.currencyid ? 
+        "0xd62971620094e8244F1ed3B12a8D31bC969081fA" 
+        : 
+        raddr;
+
+      const params = {..._params, amount: 0, address};
+
+      const res = await api.native.callDaemon(chain, 'sendcurrency', [raddr, [params], minconfs, sendfee, true]);
+
+      if (params.feecurrency == null) {
+        const chainCurrency = await api.native.get_currency(chain, chain);
+        feecurrency = chainCurrency.currencyid;
+      } else feecurrency = params.feecurrency;
+
+      return res.outputtotals[feecurrency];
+    } catch(e) {
+      throw e
+    }
+  };
+
+  api.setPost('/native/estimate_sendcurrency_fee', async (req, res, next) => {
+    const { chainTicker, params, minconfs, sendfee } = req.body;
+
+    try {
+      const retObj = {
+        msg: 'success',
+        result: await api.native.estimate_sendcurrency_fee(chainTicker, params, minconfs, sendfee),
+      };
+
+      res.send(JSON.stringify(retObj));  
+    } catch(e) {
+      const retObj = {
+        msg: 'error',
+        result: e.message,
+      };
+
+      res.send(JSON.stringify(retObj)); 
+    }
+  });
+
+  return api;
+};