From 7a65dbdcf41827def41351a7086537456ef4626f Mon Sep 17 00:00:00 2001
From: Stefan Thomas <justmoon@members.fsf.org>
Date: Tue, 12 Mar 2013 13:59:21 +0100
Subject: [PATCH] JS: Emit orderbook events when trades happen.

---
 src/js/amount.js    |  4 +++-
 src/js/orderbook.js | 17 ++++++++++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/js/amount.js b/src/js/amount.js
index 5a121d4f4..6302c39b0 100644
--- a/src/js/amount.js
+++ b/src/js/amount.js
@@ -98,6 +98,8 @@ Amount.prototype.abs = function () {
 Amount.prototype.add = function (v) {
   var result;
 
+  v = Amount.from_json(v);
+
   if (!this.is_comparable(v)) {
     result              = Amount.NaN();
   }
@@ -779,7 +781,7 @@ Amount.prototype.set_issuer = function (issuer) {
 // Result in terms of this' currency and issuer.
 Amount.prototype.subtract = function (v) {
   // Correctness over speed, less code has less bugs, reuse add code.
-  return this.add(v.negate());
+  return this.add(Amount.from_json(v).negate());
 };
 
 Amount.prototype.to_number = function (allow_nan) {
diff --git a/src/js/orderbook.js b/src/js/orderbook.js
index a420fdf8f..150743b46 100644
--- a/src/js/orderbook.js
+++ b/src/js/orderbook.js
@@ -77,7 +77,7 @@ OrderBook.prototype = new EventEmitter;
 /**
  * List of events that require a remote subscription to the orderbook.
  */
-OrderBook.subscribe_events = ['transaction', 'model'];
+OrderBook.subscribe_events = ['transaction', 'model', 'trade'];
 
 /**
  * Subscribes to orderbook.
@@ -147,6 +147,13 @@ OrderBook.prototype.notifyTx = function (message)
 
   var changed = false;
 
+  var trade_gets = Amount.from_json("0" + ((this._currency_gets === 'XRP') ? "" :
+                                    "/" + this._currency_gets +
+                                    "/" + this._issuer_gets));
+  var trade_pays = Amount.from_json("0" + ((this._currency_pays === 'XRP') ? "" :
+                                    "/" + this._currency_pays +
+                                    "/" + this._issuer_pays));
+
   message.mmeta.each(function (an) {
     if (an.entryType !== 'Offer') return;
 
@@ -164,6 +171,13 @@ OrderBook.prototype.notifyTx = function (message)
           break;
         }
       }
+
+      trade_gets = trade_gets.add(an.fieldsPrev.TakerGets);
+      trade_pays = trade_pays.add(an.fieldsPrev.TakerPays);
+      if (an.diffType === 'ModifiedNode') {
+        trade_gets = trade_gets.subtract(an.fieldsFinal.TakerGets);
+        trade_pays = trade_pays.subtract(an.fieldsFinal.TakerPays);
+      }
     } else if (an.diffType === 'CreatedNode') {
       var price = Amount.from_json(an.fields.TakerPays).ratio_human(an.fields.TakerGets);
       for (i = 0, l = self._offers.length; i < l; i++) {
@@ -187,6 +201,7 @@ OrderBook.prototype.notifyTx = function (message)
   if (this._subs) {
     this.emit('transaction', message);
     if (changed) this.emit('model', this._offers);
+    if (!trade_gets.is_zero()) this.emit('trade', trade_pays, trade_gets);
   }
 };