Merge pull request #483 from isocolsky/ref/send-max

Improve response in send max API

lib/server.js

@@ -1177,13 +1177,19 @@ WalletService.prototype.getSendMaxInfo = function(opts, cb) {
         amount: 0,
         fee: 0,
         inputs: [],
+        utxosBelowFee: 0,
+        amountBelowFee: 0,
+        utxosAboveMaxSize: 0,
+        amountAboveMaxSize: 0,
       };
 
       var inputs = _.reject(utxos, 'locked');
       if (!!opts.excludeUnconfirmedUtxos) {
         inputs = _.filter(inputs, 'confirmations');
       }
-      inputs = _.sortBy(inputs, 'satoshis');
+      inputs = _.sortBy(inputs, function(input) {
+        return -input.satoshis;
+      });
 
       if (_.isEmpty(inputs)) return cb(null, info);
 
@@ -1195,18 +1201,31 @@ WalletService.prototype.getSendMaxInfo = function(opts, cb) {
         feePerKb: opts.feePerKb,
       });
 
-      var lastFee = txp.getEstimatedFee();
+      var baseTxpSize = txp.getEstimatedSize();
-      _.eachRight(inputs, function(input) {
+      var baseTxpFee = baseTxpSize * txp.feePerKb / 1000.;
-        txp.inputs.push(input);
+      var sizePerInput = txp.getEstimatedSizeForSingleInput();
-        var fee = txp.getEstimatedFee();
+      var feePerInput = sizePerInput * txp.feePerKb / 1000.;
-        var sizeInKb = txp.getEstimatedSize() / 1000.;
+
-        if (fee - lastFee > input.satoshis || sizeInKb > Defaults.MAX_TX_SIZE_IN_KB) {
+      var partitionedByAmount = _.partition(inputs, function(input) {
-          txp.inputs.pop();
+        return input.satoshis > feePerInput;
+      });
+
+      info.utxosBelowFee = partitionedByAmount[1].length;
+      info.amountBelowFee = _.sum(partitionedByAmount[1], 'satoshis');
+      inputs = partitionedByAmount[0];
+
+      _.each(inputs, function(input, i) {
+        var sizeInKb = (baseTxpSize + (i + 1) * sizePerInput) / 1000.;
+        if (sizeInKb > Defaults.MAX_TX_SIZE_IN_KB) {
+          info.utxosAboveMaxSize = inputs.length - i;
+          info.amountAboveMaxSize = _.sum(_.slice(inputs, i), 'satoshis');
           return false;
         }
-
+        txp.inputs.push(input);
-        lastFee = fee;
       });
+
+      if (_.isEmpty(txp.inputs)) return cb(null, info);
+
       info.size = txp.getEstimatedSize();
       info.fee = txp.getEstimatedFee();
       info.amount = _.sum(txp.inputs, 'satoshis') - info.fee;

test/integration/server.js

@@ -3696,7 +3696,7 @@ describe('Wallet service', function() {
       });
     };
 
-    it('should be able to get send max info on empty wallet', function(done) {
+    it('should be able to get send max info on 0 utxo wallet', function(done) {
       server.getSendMaxInfo({
         feePerKb: 10000,
         returnInputs: true,
@@ -3707,6 +3707,10 @@ describe('Wallet service', function() {
         info.amount.should.equal(0);
         info.fee.should.equal(0);
         info.inputs.should.be.empty;
+        info.utxosBelowFee.should.equal(0);
+        info.amountBelowFee.should.equal(0);
+        info.utxosAboveMaxSize.should.equal(0);
+        info.amountAboveMaxSize.should.equal(0);
         done();
       });
     });
@@ -3722,6 +3726,10 @@ describe('Wallet service', function() {
           info.size.should.equal(1304);
           info.fee.should.equal(info.size * 10000 / 1000.);
           info.amount.should.equal(1e8 - info.fee);
+          info.utxosBelowFee.should.equal(0);
+          info.amountBelowFee.should.equal(0);
+          info.utxosAboveMaxSize.should.equal(0);
+          info.amountAboveMaxSize.should.equal(0);
           sendTx(info, done);
         });
       });
@@ -3745,7 +3753,6 @@ describe('Wallet service', function() {
         });
       });
     });
-
     it('should exclude unconfirmed inputs', function(done) {
       helpers.stubUtxos(server, wallet, ['u0.1', 0.2, 0.3, 0.4], function() {
         server.getSendMaxInfo({
@@ -3791,7 +3798,7 @@ describe('Wallet service', function() {
       });
     });
     it('should ignore utxos not contributing to total amount (below their cost in fee)', function(done) {
-      helpers.stubUtxos(server, wallet, ['u0.1', 0.2, 0.3, 0.4, 0.000001, 0.0002, 0.0003], function() {
+      helpers.stubUtxos(server, wallet, ['u0.1', 0.2, 0.3, 0.4, '1bit', '100bit', '200bit'], function() {
         server.getSendMaxInfo({
           feePerKb: 0.001e8,
           returnInputs: true,
@@ -3802,6 +3809,8 @@ describe('Wallet service', function() {
           info.size.should.equal(1304);
           info.fee.should.equal(info.size * 0.001e8 / 1000.);
           info.amount.should.equal(1e8 - info.fee);
+          info.utxosBelowFee.should.equal(3);
+          info.amountBelowFee.should.equal(301e2);
           server.getSendMaxInfo({
             feePerKb: 0.0001e8,
             returnInputs: true,
@@ -3811,12 +3820,32 @@ describe('Wallet service', function() {
             info.inputs.length.should.equal(6);
             info.size.should.equal(1907);
             info.fee.should.equal(info.size * 0.0001e8 / 1000.);
-            info.amount.should.equal(1.0005e8 - info.fee);
+            info.amount.should.equal(1.0003e8 - info.fee);
+            info.utxosBelowFee.should.equal(1);
+            info.amountBelowFee.should.equal(1e2);
             sendTx(info, done);
           });
         });
       });
     });
+    it('should work when all inputs are below their cost in fee', function(done) {
+      helpers.stubUtxos(server, wallet, ['u 10bit', '10bit', '20bit'], function() {
+        server.getSendMaxInfo({
+          feePerKb: 500e2,
+          returnInputs: true,
+        }, function(err, info) {
+          should.not.exist(err);
+          should.exist(info);
+          info.inputs.should.be.empty;
+          info.size.should.equal(0);
+          info.fee.should.equal(0);
+          info.amount.should.equal(0);
+          info.utxosBelowFee.should.equal(3);
+          info.amountBelowFee.should.equal(40e2);
+          done();
+        });
+      });
+    });
     it('should not go beyond max tx size', function(done) {
       var _oldDefault = Defaults.MAX_TX_SIZE_IN_KB;
       Defaults.MAX_TX_SIZE_IN_KB = 2;
@@ -3829,6 +3858,8 @@ describe('Wallet service', function() {
           should.exist(info);
           info.size.should.be.below(2000);
           info.inputs.length.should.be.below(9);
+          info.utxosAboveMaxSize.should.equal(3);
+          info.amountAboveMaxSize.should.equal(3e8);
           Defaults.MAX_TX_SIZE_IN_KB = _oldDefault;
           sendTx(info, done);
         });