From d26db89a2151a83a74ff9bf1aa5a65f36f83e73f Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Sun, 21 Aug 2016 11:04:56 -0700
Subject: [PATCH] mtx: refactor.

---
 lib/bcoin/mtx.js | 191 +++++++++++++++++++++++++++++------------------
 1 file changed, 118 insertions(+), 73 deletions(-)

diff --git a/lib/bcoin/mtx.js b/lib/bcoin/mtx.js
index 1ee5ca08..6f464659 100644
--- a/lib/bcoin/mtx.js
+++ b/lib/bcoin/mtx.js
@@ -700,81 +700,111 @@ MTX.prototype.signature = function signature(index, prev, key, type, version) {
  */
 
 MTX.prototype.isSigned = function isSigned() {
-  var i, input, prev, vector, m, len, j;
-
-  for (i = 0; i < this.inputs.length; i++) {
-    input = this.inputs[i];
-
-    // We can't check for signatures unless
-    // we have the previous output.
-    if (!input.coin)
+  for (var i = 0; i < this.inputs.length; i++) {
+    if (!this.isInputSigned(i))
       return false;
+  }
+};
 
-    // Get the prevout's script
-    prev = input.coin.script;
+/**
+ * Test whether an input is fully-signed.
+ * @param {Number} index
+ * @returns {Boolean}
+ */
 
-    // Script length, needed for multisig
-    vector = input.script;
-    len = vector.length;
+MTX.prototype.isInputSigned = function isInputSigned(index) {
+  var input = this.inputs[index];
+  var prev, vector, m, redeem, j, result;
 
-    // We need to grab the redeem script when
-    // signing p2sh transactions.
-    if (prev.isScripthash()) {
-      prev = input.script.getRedeem();
-      if (!prev)
-        return false;
-      len = vector.length - 1;
-    }
-
-    // If the output script is a witness program,
-    // we have to switch the vector to the witness
-    // and potentially alter the length.
-    if (prev.isWitnessScripthash()) {
-      prev = input.witness.getRedeem();
-      if (!prev)
-        return false;
-      vector = input.witness;
-      len = vector.length - 1;
-    } else if (prev.isWitnessPubkeyhash()) {
-      prev = Script.fromPubkeyhash(prev.get(1));
-      vector = input.witness;
-      len = vector.length;
-    }
-
-    if (prev.isPubkey()) {
-      if (!Script.isSignature(vector.get(0)))
-        return false;
-      continue;
-    }
-
-    if (prev.isPubkeyhash()) {
-      if (!Script.isSignature(vector.get(0)))
-        return false;
-      continue;
-    }
-
-    if (prev.isMultisig()) {
-      // Grab `m` value (number of required sigs).
-      m = prev.getSmall(0);
-
-      // Ensure all members are signatures.
-      for (j = 1; j < len; j++) {
-        if (!Script.isSignature(vector.get(j)))
-          return false;
-      }
-
-      // Ensure we have the correct number
-      // of required signatures.
-      if (len - 1 !== m)
-        return false;
-
-      continue;
-    }
+  assert(input, 'Input does not exist.');
 
+  // We can't check for signatures unless
+  // we have the previous output.
+  if (!input.coin)
     return false;
+
+  // Get the prevout's script
+  prev = input.coin.script;
+
+  // Script length, needed for multisig
+  vector = input.script;
+  redeem = false;
+
+  // We need to grab the redeem script when
+  // signing p2sh transactions.
+  if (prev.isScripthash()) {
+    prev = input.script.getRedeem();
+    if (!prev)
+      return false;
+    redeem = true;
   }
 
-  return true;
+  // If the output script is a witness program,
+  // we have to switch the vector to the witness
+  // and potentially alter the length.
+  if (prev.isWitnessScripthash()) {
+    prev = input.witness.getRedeem();
+    if (!prev)
+      return false;
+    vector = input.witness;
+    redeem = true;
+  } else if (prev.isWitnessPubkeyhash()) {
+    prev = Script.fromPubkeyhash(prev.get(1));
+    vector = input.witness;
+    redeem = false;
+  }
+
+  if (redeem) {
+    redeem = vector.pop();
+    result = this.isVectorSigned(prev);
+    vector.push(redeem);
+    return result;
+  }
+
+  return this.isVectorSigned(prev, vector);
+};
+
+/**
+ * Test whether a vector is fully-signed.
+ * @param {Script} prev
+ * @param {Script|Witness} vector
+ * @returns {Boolean}
+ */
+
+MTX.prototype.isVectorSigned = function isVectorSigned(prev, vector) {
+  var m;
+
+  if (prev.isPubkey()) {
+    if (!Script.isSignature(vector.get(0)))
+      return false;
+    return true;
+  }
+
+  if (prev.isPubkeyhash()) {
+    if (!Script.isSignature(vector.get(0)))
+      return false;
+    return true;
+  }
+
+  if (prev.isMultisig()) {
+    // Grab `m` value (number of required sigs).
+    m = prev.getSmall(0);
+
+    // Ensure all members are signatures.
+    for (j = 1; j < vector.length; j++) {
+      if (!Script.isSignature(vector.get(j)))
+        return false;
+    }
+
+    // Ensure we have the correct number
+    // of required signatures.
+    if (vector.length - 1 !== m)
+      return false;
+
+    return true;
+  }
+
+  return false;
 };
 
 /**
@@ -879,7 +909,7 @@ MTX.prototype.signAsync = function signAsync(ring, type, callback) {
  */
 
 MTX.prototype.isScripted = function isScripted() {
-  var i, input;
+  var i;
 
   if (this.outputs.length === 0)
     return false;
@@ -888,12 +918,27 @@ MTX.prototype.isScripted = function isScripted() {
     return false;
 
   for (i = 0; i < this.inputs.length; i++) {
-    input = this.inputs[i];
-
-    if (input.script.raw.length === 0
-        && input.witness.items.length === 0) {
+    if (!this.isInputScripted(i))
       return false;
-    }
+  }
+
+  return true;
+};
+
+/**
+ * Test whether the input at least
+ * has all script templates built.
+ * @returns {Boolean}
+ */
+
+MTX.prototype.isInputScripted = function isInputScripted(index) {
+  var input = this.inputs[index];
+
+  assert(input, 'Input does not exist.');
+
+  if (input.script.raw.length === 0
+      && input.witness.items.length === 0) {
+    return false;
   }
 
   return true;