From 704c95c90dd3fd5aebca7de104dccb3a702bc02c Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 20 Jan 2016 12:31:42 -0800
Subject: [PATCH] add tx.getPriority and tx.isFree.

---
 lib/bcoin/protocol/constants.js | 12 +++++-----
 lib/bcoin/tx.js                 | 39 +++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/lib/bcoin/protocol/constants.js b/lib/bcoin/protocol/constants.js
index 8f3012e3..d586a462 100644
--- a/lib/bcoin/protocol/constants.js
+++ b/lib/bcoin/protocol/constants.js
@@ -179,6 +179,10 @@ Object.keys(exports.opcodes).forEach(function(name) {
   exports.opcodesByVal[val] = name;
 });
 
+exports.coin = new bn(10000000).muln(10);
+exports.cent = new bn(1000000);
+exports.maxMoney = new bn(21000000).mul(exports.coin);
+
 exports.hashType = {
   all: 1,
   none: 2,
@@ -203,7 +207,9 @@ exports.tx = {
   maxSize: 100000,
   fee: 10000,
   dust: 5460,
-  bareMultisig: true
+  bareMultisig: true,
+  freeThreshold: exports.coin.muln(144).divn(250),
+  maxFreeSize: 1000
 };
 
 exports.script = {
@@ -259,9 +265,5 @@ exports.zeroHash = utils.toArray(
 exports.userVersion = require('../../../package.json').version;
 exports.userAgent = '/bcoin:' + exports.userVersion + '/';
 
-exports.coin = new bn(10000000).muln(10);
-exports.cent = new bn(1000000);
-exports.maxMoney = new bn(21000000).mul(exports.coin);
-
 exports.banTime = 24 * 60 * 60;
 exports.banScore = 100;
diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index e720cbb8..1fce32f8 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -1326,6 +1326,45 @@ TX.prototype.isStandardInputs = function isStandardInputs(flags) {
   return true;
 };
 
+TX.prototype.getPriority = function getPriority() {
+  var size, value, i, input, output, age;
+
+  size = this.maxSize();
+  value = new bn(0);
+
+  for (i = 0; i < this.inputs.length; i++) {
+    input = this.inputs[i];
+
+    if (!input.out.tx)
+      return constants.tx.freeThreshold.clone();
+
+    output = input.out.tx.outputs[input.out.index];
+    age = input.out.tx.getConfirmations();
+
+    if (age === -1)
+      age = 0;
+
+    if (age !== 0)
+      age += 1;
+
+    value.iadd(output.value.muln(age));
+  }
+
+  return priority.divn(size);
+};
+
+TX.prototype.isFree = function isFree() {
+  var size = this.maxSize();
+  var priority;
+
+  if (size >= constants.tx.maxFreeSize)
+    return false;
+
+  priority = this.getPriority();
+
+  return priority.cmp(constants.tx.freeThreshold) > 0;
+};
+
 TX.prototype.getHeight = function getHeight() {
   if (!this.chain)
     return -1;