✨ add ability for services to register their own commands

refs TryGhost#146
- add registerCommand utilities as well as "ghost service <name>"
command

lib/commands.js

@@ -63,6 +63,15 @@ module.exports = {
         description: 'start a managed ghost process'
     },
 
+    service: {
+        description: 'run a service-defined command',
+
+        arguments: [
+            'command',
+            {name: 'args', optional: true, variadic: true}
+        ]
+    },
+
     setup: {
         description: 'setup an installation of Ghost (after it is installed)',
 

lib/commands/service.js

@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports.execute = function execute(command, args) {
+    return this.service.callCommand(command, args);
+};

lib/services/base.js

@@ -17,6 +17,10 @@ class BaseService {
         this.serviceManager.registerHook(hook, fn, this.name);
     }
 
+    command(name, fn) {
+        this.serviceManager.registerCommand(name, fn, this.name);
+    }
+
     get config() {
         return this.serviceManager.config;
     }

lib/services/index.js

@@ -26,6 +26,7 @@ class ServiceManager {
         this.ui = ui;
 
         this.hooks = {};
+        this.commands = {};
         this.services = {};
         this.availableProcessManagers = {};
         this.process = null;
@@ -61,6 +62,29 @@ class ServiceManager {
         });
     }
 
+    registerCommand(name, fn, serviceName) {
+        if (!this.services[serviceName]) {
+            throw new Error(`Service ${serviceName} does not exist`);
+        }
+
+        if (this.commands[name]) {
+            throw new Error(`Service command ${name} is already defined`);
+        }
+
+        this.commands[name] = [serviceName, fn];
+    }
+
+    callCommand(name, args) {
+        if (!this.commands[name]) {
+            throw new Error(`Command ${name} is not defined`);
+        }
+
+        let command = this.commands[name];
+        let service = this.services[command[0]];
+
+        return Promise.resolve(service[command[1]].apply(service, args));
+    }
+
     setConfig(config, force) {
         if (this.config && !force) {
             // Config has already been set and we are not forcing a reload of the services,