Get tx fees from API instead of using bitcore's too-expensive fees

www/assets/js/crypto.js

@@ -45,19 +45,34 @@ function scanPrivateKeyQrCode(callback) {
  * @param {type} outputSatoshis Amount to send to recipient's wallet
  * @returns {string} Hex of serialized transaction, suitable for broadcast via Bitcoin Core or an API.
  */
-function createSignedTransaction(bitcoreLib, privateKeyString, sourceAddress, destinationAddress, utxos, outputSatoshis) {
+function createSignedTransaction(bitcoreLib, privateKeyString, sourceAddress, destinationAddress, utxos, outputSatoshis, feePerByte) {
+    if (typeof feePerByte == "undefined") {
+        feePerByte = -1;
+    }
     try {
         var privateKey = new bitcoreLib.PrivateKey(privateKeyString);
 
         var transaction = new bitcoreLib.Transaction()
                 .from(utxos)
                 .to(destinationAddress, outputSatoshis)
-                .change(sourceAddress)
+                .change(sourceAddress);
-                .sign(privateKey);
+
+        var size = transaction._estimateSize();
+        var fee = size * feePerByte;
+
+        if (feePerByte > -1) {
+            // use our fee
+            transaction = transaction.fee(fee);
+        } else {
+            // use lib's fee
+            fee = transaction.getFee();
+        }
+
+        transaction = transaction.sign(privateKey);
 
         var inputTotal = transaction._getInputAmount();
 
-        var outputTotal = transaction.getFee() + outputSatoshis;
+        var outputTotal = fee + outputSatoshis;
     } catch (ex) {
         throw new Error("There was an internal error while creating the transaction. Details: " + ex.message);
     }
@@ -132,9 +147,9 @@ function getUTXOData(walletaddress, successCallback, errorCallback) {
 }
 
 function sendCoins(privatekey, fromaddress, toaddress, amount) {
-    var progressdialog = app.dialog.progress("Querying blockchain...", 25);
+    var progressdialog = app.dialog.progress("Querying blockchain...", 20);
     getUTXOData(fromaddress, function (success) {
-        progressdialog.setProgress(50);
+        progressdialog.setProgress(40);
         progressdialog.setText("Creating transaction...");
         if (success.utxos.length == 0) {
             app.dialog.close();
@@ -160,8 +175,14 @@ function sendCoins(privatekey, fromaddress, toaddress, amount) {
                 return;
         }
 
+        progressdialog.setProgress(60);
+        progressdialog.setText("Calculating fees...");
+        apirequest(SETTINGS.apis.cryptofees, {
+            currency: success.currency
+        }, function (resp) {
+            if (resp.status == "OK") {
                 try {
-            var txdata = createSignedTransaction(bitcore, privatekey, fromaddress, toaddress, utxos, satoshis);
+                    var txdata = createSignedTransaction(bitcore, privatekey, fromaddress, toaddress, utxos, satoshis, resp.feePerByte);
                 } catch (ex) {
                     console.error(ex);
                     app.dialog.close();
@@ -169,7 +190,7 @@ function sendCoins(privatekey, fromaddress, toaddress, amount) {
                     return;
                 }
 
-        progressdialog.setProgress(75);
+                progressdialog.setProgress(80);
                 progressdialog.setText("Sending payment...");
 
                 apirequest(SETTINGS.apis.broadcasttransaction, {
@@ -183,6 +204,7 @@ function sendCoins(privatekey, fromaddress, toaddress, amount) {
                         return;
                     } else {
                         app.dialog.close();
+                        app.dialog.alert(resp.msg, "Error");
                     }
                 }, function (errorData) {
                     app.dialog.close();
@@ -200,6 +222,26 @@ function sendCoins(privatekey, fromaddress, toaddress, amount) {
                         sendErrorReport("Crypto", "Couldn't broadcast transaction", "Server/network problem: " + xhr.status + ": " + xhr.statusText);
                     }
                 });
+            } else {
+                app.dialog.close();
+                app.dialog.alert(resp.msg, "Error");
+            }
+        }, function (errorData) {
+            app.dialog.close();
+            try {
+                var error = $.parseJSON(errorData.responseText);
+                if (error && typeof error.msg != 'undefined') {
+                    app.dialog.alert(error.msg, "Error");
+                    sendErrorReport("Crypto", "Couldn't get transaction fees", error.msg);
+                } else {
+                    app.dialog.alert("There's a server or network problem. Check your Internet connection or try again later. Your funds are safe.", "Error");
+                    sendErrorReport("Crypto", "Couldn't get transaction fees", "Server/network problem: " + xhr.status + ": " + xhr.statusText);
+                }
+            } catch (ex) {
+                app.dialog.alert("There's a server or network problem. Check your Internet connection or try again later. Your funds are safe.", "Error");
+                sendErrorReport("Crypto", "Couldn't get transaction fees", "Server/network problem: " + xhr.status + ": " + xhr.statusText);
+            }
+        });
     }, function (error) {
         app.dialog.close();
         app.dialog.alert(error, "Error");

www/settings.js

@@ -41,7 +41,8 @@ var SETTINGS = {
         // Crypto: check balance and send transactions
         walletbalance: "http://localhost/helena.express/apis/crypto/walletbalance",
         getutxo: "http://localhost/helena.express/apis/crypto/getutxo",
-        broadcasttransaction: "http://localhost/helena.express/apis/crypto/broadcasttransaction"
+        broadcasttransaction: "http://localhost/helena.express/apis/crypto/broadcasttransaction",
+        cryptofees: "http://localhost/helena.express/apis/crypto/fees"
     },
     stripe_pubkey: "pk_test_51J6qFXCa1Fboir5UzPO3LCiMsVNiFP2lq4wR0dEcjJJVzAaJ3uRggDekZPB3qeYpMD3ayIYHKyD5sSn0IFLlEXMW001LqrvGSH",
     branding: {