wallet: Fix node client interface for hooks.

bsock hooks that nodeclient tries to imitate, are handlers set on
specific event. They are expected to return results to the caller.

lib/wallet/nodeclient.js

@@ -7,6 +7,7 @@
 'use strict';
 
 const assert = require('bsert');
+const blacklist = require('bsock/lib/blacklist');
 const AsyncEmitter = require('bevent');
 
 /**
@@ -27,6 +28,7 @@ class NodeClient extends AsyncEmitter {
     this.network = node.network;
     this.filter = null;
     this.opened = false;
+    this.hooks = new Map();
 
     this.init();
   }
@@ -98,13 +100,46 @@ class NodeClient extends AsyncEmitter {
   }
 
   /**
-   * Add a listener.
-   * @param {String} type
+   * Add a hook.
+   * @param {String} event
    * @param {Function} handler
    */
 
-  hook(type, handler) {
-    return this.on(type, handler);
+  hook(event, handler) {
+    assert(typeof event === 'string', 'Event must be a string.');
+    assert(typeof handler === 'function', 'Handler must be a function.');
+    assert(!this.hooks.has(event), 'Hook already bound.');
+    assert(!Object.prototype.hasOwnProperty.call(blacklist, event),
+      'Blacklisted event.');
+    this.hooks.set(event, handler);
+  }
+
+  /**
+   * Remove a hook.
+   * @param {String} event
+   */
+
+  unhook(event) {
+    assert(typeof event === 'string', 'Event must be a string.');
+    assert(!Object.prototype.hasOwnProperty.call(blacklist, event),
+      'Blacklisted event.');
+    this.hooks.delete(event);
+  }
+
+  /**
+   * Call a hook.
+   * @param {String} event
+   * @param {...Object} args
+   * @returns {Promise}
+   */
+
+  handleCall(event, ...args) {
+    const hook = this.hooks.get(event);
+
+    if (!hook)
+      throw new Error('No hook available.');
+
+    return hook(...args);
   }
 
   /**
@@ -215,8 +250,6 @@ class NodeClient extends AsyncEmitter {
   /**
    * Rescan for any missed transactions.
    * @param {Number|Hash} start - Start block.
-   * @param {Bloom} filter
-   * @param {Function} iter - Iterator.
    * @returns {Promise}
    */
 
@@ -225,7 +258,7 @@ class NodeClient extends AsyncEmitter {
       return this.node.chain.reset(start);
 
     return this.node.chain.scan(start, this.filter, (entry, txs) => {
-      return this.emitAsync('block rescan', entry, txs);
+      return this.handleCall('block rescan', entry, txs);
     });
   }