Implement plugin object support; pass dot to app

We now support plugins that are more than functions. At the moment these
plugin modules should export a plain object with the following possible
properties:

  * priority number
    * preload/load priority. Higher numbers result in earlier calling.
  * preload function
    * Any logic for preloading, just as dynamic/initial setup that may be used by other plugins.
  * load
    * Any logic for setting up the bulk of the plugin, such as express paths and similar.

index.js

@@ -24,13 +24,14 @@ const app = {
     menu: '',
   },
   express: exp,
+  dot: null,
 }
 
 const pub = __dirname + '/public'
 const views = __dirname + '/views'
 const routes = __dirname + '/routes'
 
-const dot = doT.process({'path': views})
+app.dot = doT.process({'path': views})
 
 try { 
   app.config = {...app.config, ...require(__dirname + '/config.js')}
@@ -43,7 +44,7 @@ try {
 exp.use(express.static(pub))
 exp.use(express.static(path.join(__dirname, app.config.srd)))
 exp.engine('dot', (template, options, cb) => {
-  return cb(null, dot[path.parse(template).name](options))
+  return cb(null, app.dot[path.parse(template).name](options))
 })
 
 exp.set('views', views)
@@ -55,7 +56,7 @@ try {
   fs.readdirSync('plugins').forEach(f => {
     let plugin_path = path.resolve('plugins', f)
     if (fs.lstatSync(plugin_path).isDirectory()) {
-      console.log('plugin preload:', f)
+      console.log('plugin require:', f)
       try {
         let plugin = {
           defaults: null,
@@ -87,6 +88,47 @@ try {
   })
   if (plugins.length === 0) {
     console.warn('no plugins found');
+  } else {
+    // Sort our plugins according to desired priorities. Higher numbers 
+    plugins.sort((first, second) => {
+      let first_priority = 0
+      let second_priority = 0
+      if (first.config.priority !== undefined) {
+        first_priority = first.config.priority
+      } else if (first.module === Object(first.module)) {
+        if (first.module.priority !== undefined) {
+          first_priority = first.module.priority
+        }
+      }
+      if (second.config.priority !== undefined) {
+        second_priority = second.config.priority
+      } else if (second.module === Object(second.module)) {
+        if (second.module.priority !== undefined) {
+          second_priority = second.module.priority
+        }
+      }
+      if (first_priority > second_priority) {
+        return -1
+      } else if (first_priority < second_priority) {
+        return 1
+      }
+      return 0
+    })
+    // Call any needed preloads.
+    for (let plugin of plugins) {
+      // Call preload if the module is an object.
+      if (plugin.module === Object(plugin.module)) {
+        if (plugin.module.preload) {
+          console.log('plugin preload:', f)
+          try {
+            plugin.module.preload(plugin, app)
+            console.log('...ok')
+          } catch(err) {
+            console.error('...fail: ', err)
+          }
+        }
+      }
+    }
   }
 } catch(err) {
   if (err.code === 'ENOENT') {
@@ -120,7 +162,13 @@ const server = exp.listen(port, async () => {
 
   for (let plugin of plugins) {
     try {
-      await plugin.module(plugin, app)
+      if (plugin.module instanceof Function) {
+        await plugin.module(plugin, app)
+      } else if (plugin.module === Object(plugin.module)) {
+        if (plugin.module.load) {
+          await plugin.module.load(plugin, app)
+        }
+      }
     } catch(err) {
       console.error('plugin', err)
     }