convert api-early hook to plugin

Author: goto-bus-stop

src/ExtPlug.js

@@ -9,6 +9,7 @@ import PluginsCollection from './collections/PluginsCollection';
 import Plugin from './Plugin';
 import * as pluginLoader from './pluginLoader';
 
+import EarlyAPIEventsPlugin from './plugins/EarlyAPIEventsPlugin';
 import CommandsPlugin from './plugins/CommandsPlugin';
 import SettingsTabPlugin from './plugins/SettingsTabPlugin';
 import ChatTypePlugin from './plugins/ChatTypePlugin';
@@ -87,6 +88,7 @@ const ExtPlug = Plugin.extend({
     this._super('extplug', this);
 
     this.corePlugins = [
+      new EarlyAPIEventsPlugin('extplug:early-api', this),
       new CommandsPlugin('extplug:chat-commands', this),
       new SettingsTabPlugin('extplug:settings-tab', this),
       new MoreChatEventsPlugin('extplug:more-chat-events', this),

src/hooks/api-early.js

@@ -1,9 +1,7 @@
-import * as apiEarlyHook from './api-early';
 import * as playbackHook from './playback';
 import * as popoutStyleHook from './popout-style';
 
 export default [
-  apiEarlyHook,
   playbackHook,
   popoutStyleHook,
 ];

src/hooks/index.js

@@ -0,0 +1,51 @@
+import meld from 'meld';
+import Plugin from '../Plugin';
+
+function nop() { return 'Dummy handler to ensure that plug.dj actually triggers the event'; }
+
+// find default plug.dj API event names
+const eventKeys = Object.keys(API).filter(key =>
+  key.toUpperCase() === key && typeof API[key] === 'string'
+);
+
+const EarlyAPIEventsPlugin = Plugin.extend({
+  name: 'Early API Events',
+  description:
+    'Adds "Early" API events. Handlers for these events will always be called ' +
+    'before other handlers.',
+
+  enable() {
+    this.advice = meld.around(API, 'dispatch', this.intercept);
+    eventKeys.forEach(key => {
+      // add the API constants for these, too
+      API[`BEFORE_${key}`] = `before${API[key].charAt(0).toUpperCase()}${API[key].slice(1)}`;
+      // plug.dj checks if an event is actually attached (through the _events hash)
+      // before dispatching. We might run into situations where there is a BEFORE_
+      // handler, but not a normal one, and we do need to get the BEFORE_ event to
+      // trigger there. So we just pretend like we have handlers for all the things.
+      API.on(API[key], nop);
+    });
+  },
+
+  disable() {
+    eventKeys.forEach(key => {
+      delete API[`BEFORE_${key}`];
+      API.off(key, nop);
+    });
+    this.advice.remove();
+  },
+
+  intercept(joinpoint) {
+    const [eventName, ...params] = joinpoint.args;
+
+    API.trigger.apply(
+      API,
+      // userLeave → beforeUserLeave
+      [`before${eventName.charAt(0).toUpperCase()}${eventName.slice(1)}`, ...params]
+    );
+
+    return joinpoint.proceed();
+  },
+});
+
+export default EarlyAPIEventsPlugin;