js: Add `define.js`

library/Icinga/Web/JavaScript.php

@@ -14,7 +14,7 @@ class JavaScript
     /** @var string */
     const DEFINE_RE = '/(?<!\.)define\(\s*([\'"][^\'"]*[\'"])?[,\s]*(\[[^]]*\])?[,\s]*(function\s*\([^)]*\)|[^=]*=>)/';
 
-    protected static $jsFiles = array(
+    protected static $jsFiles = [
         'js/helpers.js',
         'js/icinga.js',
         'js/icinga/logger.js',
@@ -41,12 +41,16 @@ class JavaScript
         'js/icinga/behavior/filtereditor.js',
         'js/icinga/behavior/selectable.js',
         'js/icinga/behavior/modal.js'
-    );
+    ];
 
-    protected static $vendorFiles = array(
+    protected static $vendorFiles = [
         'js/vendor/jquery-3.4.1',
         'js/vendor/jquery-migrate-3.1.0'
-    );
+    ];
+
+    protected static $baseFiles = [
+        'js/define.js'
+    ];
 
     public static function sendMinified()
     {
@@ -74,6 +78,12 @@ class JavaScript
             $vendorFiles[] = $basedir . '/' . $file . $min . '.js';
         }
 
+        // Prepare base file list
+        $baseFiles = [];
+        foreach (self::$baseFiles as $file) {
+            $baseFiles[] = $basedir . '/' . $file;
+        }
+
         // Prepare library file list
         $libraryFiles = [];
         foreach (Icinga::app()->getLibraries() as $library) {
@@ -107,7 +117,7 @@ class JavaScript
         }
 
         $sharedFiles = array_unique($sharedFiles);
-        $files = array_merge($vendorFiles, $libraryFiles, $jsFiles, $sharedFiles);
+        $files = array_merge($vendorFiles, $baseFiles, $libraryFiles, $jsFiles, $sharedFiles);
 
         $request = Icinga::app()->getRequest();
         $noCache = $request->getHeader('Cache-Control') === 'no-cache' || $request->getHeader('Pragma') === 'no-cache';
@@ -134,6 +144,10 @@ class JavaScript
             $out .= ';' . ltrim(trim(file_get_contents($file)), ';') . "\n";
         }
 
+        foreach ($baseFiles as $file) {
+            $js .= file_get_contents($file) . "\n\n\n";
+        }
+
         // Library files need to be namespaced first before they can be included
         foreach (Icinga::app()->getLibraries() as $library) {
             foreach ($library->getJsAssets() as $file) {

public/js/define.js

@@ -0,0 +1,102 @@
+/*! Icinga Web 2 | (c) 2020 Icinga GmbH | GPLv2+ */
+
+(function(window) {
+
+    'use strict';
+
+    /**
+     * Provide a reference to be later required by foreign code
+     *
+     * @param {string} name Optional, defaults to the name (and path) of the file
+     * @param {string[]} requirements Optional, list of required references, may be relative if from the same package
+     * @param {function} factory Required, function that accepts as many params as there are requirements and that
+     *                           produces a value to be referenced
+     */
+    var define = function (name, requirements, factory) {
+        define.defines[name] = {
+            requirements: requirements,
+            factory: factory,
+            ref: null
+        }
+
+        define.resolve(name);
+    }
+
+    /**
+     * Return whether the given name references a value
+     *
+     * @param {string} name The absolute name of the reference
+     * @return {boolean}
+     */
+    define.has = function (name) {
+        return name in define.defines && define.defines[name]['ref'] !== null;
+    }
+
+    /**
+     * Get the value of a reference
+     *
+     * @param {string} name The absolute name of the reference
+     * @return {*}
+     */
+    define.get = function (name) {
+        return define.defines[name]['ref'];
+    }
+
+    /**
+     * Set the value of a reference
+     *
+     * @param {string} name The absolute name of the reference
+     * @param {*} ref The value to reference
+     */
+    define.set = function (name, ref) {
+        define.defines[name]['ref'] = ref;
+    }
+
+    /**
+     * Resolve a reference and, if successful, dependent references
+     *
+     * @param {string} name The absolute name of the reference
+     * @return {boolean}
+     */
+    define.resolve = function (name) {
+        var requirements = define.defines[name]['requirements'];
+        if (requirements.filter(define.has).length < requirements.length) {
+            return false;
+        }
+
+        var requiredRefs = [];
+        for (var i = 0; i < requirements.length; i++) {
+            requiredRefs.push(define.get(requirements[i]));
+        }
+
+        var factory = define.defines[name]['factory'];
+        define.set(name, factory.apply(null, requiredRefs));
+
+        for (var definedName in define.defines) {
+            if (define.defines[definedName]['requirements'].indexOf(name) >= 0) {
+                define.resolve(definedName);
+            }
+        }
+    }
+
+    /**
+     * Require a reference
+     *
+     * @param {string} name The absolute name of the reference
+     * @return {*}
+     */
+    var require = function(name) {
+        if (define.has(name)) {
+            return define.get(name);
+        }
+
+        throw new ReferenceError(name + ' is not defined');
+    }
+
+    define.icinga = true;
+    define.defines = {};
+
+    window.define = define;
+    window.require = require;
+
+})(window);