feat(Wallet): support bloom filtering

lib/wallet.js

@@ -50,6 +50,8 @@ var Wallet = module.exports = function (opts, cb) {
 
   this.feePerKb = opts.feePerKb || 10000
 
+  this.filters = []
+
   this._error = this._error.bind(this)
   this.initialized = false
   this._initialize(cb)
@@ -598,6 +600,7 @@ Wallet.prototype._generateKeys = function (cb) {
           path: 'm/0/' + i
         }
         self.store.put(hash.toString('base64'), value, cb)
+        self.emit('genkey', key, i)
       })
     })(i)
   }
@@ -716,3 +719,19 @@ Wallet.prototype._saveState = function (cb) {
   }
   this.store.put('state', state, cb)
 }
+
+Wallet.prototype.addFilter = function (filter) {
+  if (this.filters.indexOf(filter) !== -1) return
+  this.filters.push(filter)
+  function addKey (hdkey) {
+    var pubkey = hdkey.publicKey
+    filter.insert(pubkey.toBuffer())
+    filter.insert(keyHash(pubkey.toBuffer()))
+  }
+  if (this.state) {
+    for (var i = 0; i < this.state.gen; i++) {
+      addKey(this.deriveKey(i))
+    }
+  }
+  this.on('genkey', addKey)
+}