add hd scanning to wallet.

lib/bcoin/hd.js

@@ -268,6 +268,8 @@ HDPrivateKey.prototype.scan44 = function scan44(options, txByAddress, callback)
           if (total === 0) {
             if (chainConstant === 0)
               return chainCheck(1);
+            if (isAccount)
+              return callback(null, accounts[accountIndex]);
             return callback(null, accounts);
           }
 
@@ -276,7 +278,7 @@ HDPrivateKey.prototype.scan44 = function scan44(options, txByAddress, callback)
           if (isAccount) {
             if (chainConstant === 0)
               return chainCheck(1);
-            return callback(null, accounts[0]);
+            return callback(null, accounts[accountIndex]);
           }
 
           return scanner(accountIndex + 1);

lib/bcoin/wallet.js

@@ -664,6 +664,175 @@ Wallet.prototype.syncOutputDepth = function syncOutputDepth(tx) {
     this.setReceiveDepth(depth.receive + 1);
 };
 
+Wallet.prototype.scan = function scan(txByAddress, callback) {
+  function done(err, depths) {
+    if (err)
+      return callback(err);
+
+    if (depths.changeDepth >= this.changeDepth)
+      this.setChangeDepth(depths.changeDepth + 1);
+
+    if (depths.receiveDepth >= this.receiveDepth)
+      this.setReceiveDepth(depths.receiveDepth + 1);
+  }
+
+  if (this.derivation === 'bip44')
+    return this._scan44({ current: true }, txByAddress, done);
+
+  if (this.derivation === 'bip45')
+    return this._scan45({}, txByAddress, done);
+};
+
+Wallet.prototype._scan44 = function scan44(options, txByAddress, callback) {
+  var self = this;
+  var accounts = [];
+  var isAccount = this.master.isAccount44();
+  var _accountKey = this.accountKey;
+
+  assert(this._initialized);
+
+  return (function chainCheck(change) {
+    return (function scanner(accountIndex) {
+      var addressIndex = 0;
+      var total = 0;
+      var gap = 0;
+
+      if (options.current)
+        accountIndex = self.accountIndex;
+
+      // 1. derive the first account's node (index = 0)
+      self.accountKey = isAccount
+        ? self.master
+        : self.master.deriveAccount44(accountIndex);
+
+      if (isAccount)
+        accountIndex = new bn(self.master.childIndex).toNumber() - constants.hd.hardened;
+
+      // 2. derive the external chain node of this account
+      // 3. scan addresses of the external chain;
+      // respect the gap limit described below
+      return (function next() {
+        var address = self.deriveAddress(change, addressIndex++);
+        var addr = address.getAddress();
+
+        return txByAddress(addr, function(err, txs) {
+          var result;
+
+          if (err) {
+            self.accountKey = _accountKey;
+            return callback(err);
+          }
+
+          if (txs) {
+            if (typeof txs === 'boolean')
+              result = txs;
+            else if (typeof txs === 'number')
+              result = txs > 0;
+            else if (Array.isArray(txs))
+              result = txs.length > 0;
+            else
+              result = false;
+          }
+
+          if (result) {
+            total++;
+            gap = 0;
+            return next();
+          }
+
+          if (++gap < 20)
+            return next();
+
+          assert(accounts[accountIndex] == null || change === true);
+
+          if (change === false)
+            accounts[accountIndex] = { receiveDepth: addressIndex };
+          else
+            accounts[accountIndex].changeDepth = addressIndex;
+
+          // 4. if no transactions are found on the
+          // external chain, stop discovery
+          if (total === 0) {
+            if (change === false)
+              return chainCheck(true);
+            self.accountKey = _accountKey;
+            if (isAccount || options.current)
+              return callback(null, accounts[accountIndex]);
+            return callback(null, accounts);
+          }
+
+          // 5. if there are some transactions, increase
+          // the account index and go to step 1
+          if (isAccount || options.current) {
+            if (change === false)
+              return chainCheck(true);
+            self.accountKey = _accountKey;
+            return callback(null, accounts[accountIndex]);
+          }
+
+          return scanner(accountIndex + 1);
+        });
+      })();
+    })(0);
+  })(false);
+};
+
+Wallet.prototype._scan45 = function scan45(options, txByAddress, callback) {
+  var depths = { changeDepth: 0, receiveDepth: 0 };
+
+  assert(this._initialized);
+
+  return (function chainCheck(change) {
+    var addressIndex = 0;
+    var total = 0;
+    var gap = 0;
+
+    return (function next() {
+      var address = self.deriveAddress(change, addressIndex++);
+      var addr = address.getAddress();
+
+      return txByAddress(addr, function(err, txs) {
+        var result;
+
+        if (err)
+          return callback(err);
+
+        if (txs) {
+          if (typeof txs === 'boolean')
+            result = txs;
+          else if (typeof txs === 'number')
+            result = txs > 0;
+          else if (Array.isArray(txs))
+            result = txs.length > 0;
+          else
+            result = false;
+        }
+
+        if (result) {
+          total++;
+          gap = 0;
+          return next();
+        }
+
+        if (++gap < 20)
+          return next();
+
+        assert(depths.receiveDepth === 0 || change === true);
+
+        if (change === false)
+          depths.receiveDepth = addressIndex;
+        else
+          depths.changeDepth = addressIndex;
+
+        if (change === false)
+          return chainCheck(true);
+
+        return callback(null, depths);
+      });
+    })();
+  })(false);
+};
+
 Wallet.prototype.scriptInputs = function scriptInputs(tx, index) {
   this.fillPrevout(tx);
   var addresses = this.deriveInputs(tx);