From 7d3eb8f3fa67580bd125beac83e3fc6cf5089d75 Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Wed, 2 Nov 2016 16:46:25 -0700
Subject: [PATCH] account: lookahead option.

---
 lib/wallet/account.js | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/lib/wallet/account.js b/lib/wallet/account.js
index e90bbd9f..79c1f864 100644
--- a/lib/wallet/account.js
+++ b/lib/wallet/account.js
@@ -49,7 +49,6 @@ function Account(db, options) {
   this.db = db;
   this.network = db.network;
   this.wallet = null;
-  this.lookahead = Account.MAX_LOOKAHEAD;
 
   this.receive = null;
   this.change = null;
@@ -68,6 +67,7 @@ function Account(db, options) {
   this.receiveDepth = 0;
   this.changeDepth = 0;
   this.nestedDepth = 0;
+  this.lookahead = 5;
   this.accountKey = null;
   this.keys = [];
 
@@ -175,6 +175,13 @@ Account.prototype.fromOptions = function fromOptions(options) {
     this.nestedDepth = options.nestedDepth;
   }
 
+  if (options.lookahead != null) {
+    assert(utils.isNumber(options.lookahead));
+    assert(options.lookahead >= 0);
+    assert(options.lookahead <= Account.MAX_LOOKAHEAD);
+    this.lookahead = options.lookahead;
+  }
+
   this.accountKey = options.accountKey;
 
   if (this.n > 1)
@@ -211,7 +218,7 @@ Account.fromOptions = function fromOptions(db, options) {
  * @const {Number}
  */
 
-Account.MAX_LOOKAHEAD = 10;
+Account.MAX_LOOKAHEAD = 20;
 
 /**
  * Attempt to intialize the account (generating
@@ -670,7 +677,7 @@ Account.prototype.syncDepth = co(function* syncDepth(receive, change, nested) {
   if (receive > this.receiveDepth) {
     depth = this.receiveDepth + this.lookahead;
 
-    assert(receive < depth);
+    assert(receive <= depth);
 
     for (i = depth; i < receive + this.lookahead; i++) {
       key = this.deriveReceive(i);
@@ -687,7 +694,7 @@ Account.prototype.syncDepth = co(function* syncDepth(receive, change, nested) {
   if (change > this.changeDepth) {
     depth = this.changeDepth + this.lookahead;
 
-    assert(change < depth);
+    assert(change <= depth);
 
     for (i = depth; i < change + this.lookahead; i++) {
       key = this.deriveChange(i);
@@ -703,7 +710,7 @@ Account.prototype.syncDepth = co(function* syncDepth(receive, change, nested) {
   if (this.witness && nested > this.nestedDepth) {
     depth = this.nestedDepth + this.lookahead;
 
-    assert(nested < depth);
+    assert(nested <= depth);
 
     for (i = depth; i < nested + this.lookahead; i++) {
       key = this.deriveNested(i);
@@ -781,6 +788,7 @@ Account.prototype.inspect = function inspect() {
     receiveDepth: this.receiveDepth,
     changeDepth: this.changeDepth,
     nestedDepth: this.nestedDepth,
+    lookahead: this.lookahead,
     address: this.initialized
       ? this.receive.getAddress()
       : null,
@@ -815,6 +823,7 @@ Account.prototype.toJSON = function toJSON(minimal) {
     receiveDepth: this.receiveDepth,
     changeDepth: this.changeDepth,
     nestedDepth: this.nestedDepth,
+    lookahead: this.lookahead,
     receiveAddress: this.receive
       ? this.receive.getAddress('base58')
       : null,
@@ -850,6 +859,7 @@ Account.prototype.toRaw = function toRaw(writer) {
   p.writeU32(this.receiveDepth);
   p.writeU32(this.changeDepth);
   p.writeU32(this.nestedDepth);
+  p.writeU8(this.lookahead);
   p.writeBytes(this.accountKey.toRaw());
   p.writeU8(this.keys.length);
 
@@ -885,6 +895,7 @@ Account.prototype.fromRaw = function fromRaw(data) {
   this.receiveDepth = p.readU32();
   this.changeDepth = p.readU32();
   this.nestedDepth = p.readU32();
+  this.lookahead = p.readU8();
   this.accountKey = HD.fromRaw(p.readBytes(82));
 
   assert(Account.typesByVal[this.type]);