From 0abf791bb71e92cbf9a514fc1ea08774e799990b Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sun, 12 Jun 2016 05:23:28 -0700
Subject: [PATCH] deferred.

---
 lib/bcoin/coins.js | 154 ++++++++++++++++++++-------------------------
 1 file changed, 69 insertions(+), 85 deletions(-)

diff --git a/lib/bcoin/coins.js b/lib/bcoin/coins.js
index 7849a39d..58c3dc75 100644
--- a/lib/bcoin/coins.js
+++ b/lib/bcoin/coins.js
@@ -115,48 +115,6 @@ Coins.prototype.spend = function spend(index) {
   return coin;
 };
 
-/**
- * Fill transaction(s) with coins.
- * @param {TX} tx
- * @param {Boolean?} spend - Whether the coins should
- * be spent when filling.
- * @returns {Boolean} True if all inputs were filled.
- */
-
-Coins.prototype.fill = function fill(tx) {
-  var res = true;
-  var i, input, prevout;
-
-  for (i = 0; i < tx.inputs.length; i++) {
-    input = tx.inputs[i];
-    prevout = input.prevout;
-    if (prevout.hash !== this.hash)
-      continue;
-    input.coin = this.spend(prevout.index);
-    if (!input.coin)
-      res = false;
-  }
-
-  return res;
-};
-
-/**
- * Convert collection to an array.
- * @returns {Coin[]}
- */
-
-Coins.prototype.toArray = function toArray() {
-  var out = [];
-  var i;
-
-  for (i = 0; i < this.outputs.length; i++) {
-    if (this.outputs[i])
-      out.push(this.outputs[i]);
-  }
-
-  return out;
-};
-
 /**
  * Serialize the coins object.
  * @param {TX|Coins} tx
@@ -187,7 +145,7 @@ Coins.prototype.toRaw = function toRaw(writer) {
     }
 
     if (output instanceof DeferredCoin) {
-      p.writeBytes(output.raw);
+      p.writeBytes(output.toRaw());
       continue;
     }
 
@@ -228,7 +186,7 @@ Coins.prototype.toRaw = function toRaw(writer) {
 Coins.parseRaw = function parseRaw(data, hash, index) {
   var p = new BufferReader(data);
   var i = 0;
-  var version, height, coins, mask, prefix, raw;
+  var version, height, coins, mask, prefix, offset, size;
 
   version = p.readVarint();
   height = p.readU32();
@@ -245,8 +203,7 @@ Coins.parseRaw = function parseRaw(data, hash, index) {
     coins.height = -1;
 
   while (p.left()) {
-    p.start();
-
+    offset = p.start();
     mask = p.readU8();
 
     if (mask === 0xff) {
@@ -272,15 +229,14 @@ Coins.parseRaw = function parseRaw(data, hash, index) {
 
     p.readVarint();
 
+    size = p.end();
+
     if (index != null && i !== index) {
-      p.end();
       i++;
       continue;
     }
 
-    raw = p.endData(true);
-
-    coins.outputs.push(new DeferredCoin(raw));
+    coins.outputs.push(new DeferredCoin(offset, size, data));
 
     if (index != null)
       return coins.outputs[0].toCoin(coins, i);
@@ -288,44 +244,11 @@ Coins.parseRaw = function parseRaw(data, hash, index) {
     i++;
   }
 
+  assert(index == null, 'Bad index.');
+
   return coins;
 };
 
-function DeferredCoin(raw) {
-  this.raw = raw;
-}
-
-DeferredCoin.prototype.toCoin = function toCoin(coins, index) {
-  var p = new BufferReader(this.raw);
-  var prefix = p.readU8() & 3;
-  var script, value;
-
-  if (prefix === 0)
-    script = new bcoin.script(bcoin.protocol.parser.parseScript(p));
-  else if (prefix === 1)
-    script = bcoin.script.createPubkeyhash(p.readBytes(20));
-  else if (prefix === 2)
-    script = bcoin.script.createScripthash(p.readBytes(20));
-  else
-    assert(false, 'Bad prefix.');
-
-  value = p.readVarint();
-
-  return new bcoin.coin({
-    version: coins.version,
-    coinbase: coins.coinbase,
-    height: coins.height,
-    hash: coins.hash,
-    index: index,
-    script: script,
-    value: value
-  });
-};
-
-DeferredCoin.prototype.toRaw = function toRaw() {
-  return this.raw;
-};
-
 /**
  * Parse a single serialized coin.
  * @param {Buffer} data
@@ -335,6 +258,7 @@ DeferredCoin.prototype.toRaw = function toRaw() {
  */
 
 Coins.parseCoin = function parseCoin(data, hash, index) {
+  assert(index != null, 'Bad index.');
   return Coins.parseCoins(data, hash, index);
 };
 
@@ -376,6 +300,66 @@ Coins.fromTX = function fromTX(tx) {
   });
 };
 
+/**
+ * A "deferred" coin is an object which defers
+ * parsing of a compressed coin. Say there is
+ * a transaction with 100 outputs. When block
+ * comes in, there may only be _one_ input in
+ * that entire block which redeems an output
+ * from that transaction. When parsing the
+ * Coins, there is no sense to get _all_ of
+ * them into their abstract form. A "deferred"
+ * coin is just a pointer to that coin in the
+ * Coins buffer, as well as a size. Parsing
+ * is done only if that coin is being redeemed.
+ * @exposes DeferredCoin
+ * @constructor
+ * @private
+ * @param {Number} offset
+ * @param {Number} size
+ * @param {Buffer} raw
+ */
+
+function DeferredCoin(offset, size, raw) {
+  this.offset = offset;
+  this.size = size;
+  this.raw = raw;
+}
+
+DeferredCoin.prototype.toCoin = function toCoin(coins, index) {
+  var p = new BufferReader(this.raw);
+  var prefix, script, value;
+
+  p.seek(this.offset);
+
+  prefix = p.readU8() & 3;
+
+  if (prefix === 0)
+    script = new bcoin.script(bcoin.protocol.parser.parseScript(p));
+  else if (prefix === 1)
+    script = bcoin.script.createPubkeyhash(p.readBytes(20));
+  else if (prefix === 2)
+    script = bcoin.script.createScripthash(p.readBytes(20));
+  else
+    assert(false, 'Bad prefix.');
+
+  value = p.readVarint();
+
+  return new bcoin.coin({
+    version: coins.version,
+    coinbase: coins.coinbase,
+    height: coins.height,
+    hash: coins.hash,
+    index: index,
+    script: script,
+    value: value
+  });
+};
+
+DeferredCoin.prototype.toRaw = function toRaw() {
+  return this.raw.slice(this.offset, this.offset + this.size);
+};
+
 /*
  * Helpers
  */