Add "asset" helper to the repository.

src/mibew/libs/classes/Mibew/Handlebars/Helper/AssetHelper.php

@@ -0,0 +1,138 @@
+<?php
+/*
+ * This file is a part of Mibew Messenger.
+ *
+ * Copyright 2005-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Mibew\Handlebars\Helper;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+use Mibew\Asset\AssetUrlGeneratorAwareInterface;
+use Mibew\Asset\AssetUrlGeneratorInterface;
+
+/**
+ * A helper that generates URLs for assets.
+ *
+ * Example of usage:
+ * <code>
+ *   {{asset "js/libs/super_lib.js"}}
+ * </code>
+ *
+ * One can use locations passed to class constructor as a prefixes in relative
+ * paths. Lets assume that the following array is passed to the constructor:
+ * <code>
+ *   $helper = new AssetHelper(
+ *     $generator,
+ *     array('CustomStorage' => 'custom/files/storage')
+ *   );
+ * </code>
+ *
+ * Then in a template you can do something like the following:
+ * <code>
+ *   {{asset "@CustomStorage/images/the_best_logo.png"}}
+ * <code>
+ */
+class AssetHelper implements HelperInterface, AssetUrlGeneratorAwareInterface
+{
+    /**
+     * @var array
+     */
+    protected $locations = null;
+
+    /**
+     * @var AssetUrlGeneratorInterface|null
+     */
+    protected $generator = null;
+
+    /**
+     * Class constructor.
+     *
+     * @param AssetUrlGeneratorInterface $generator An instance of URL generator
+     * @param array $locations Associative array of locations that can be used
+     *   as prefixes for asset relative paths. The keys are prefixes and the
+     *   values are locations relative paths. These paths must not content
+     *   neither leading nor trailing slashes.
+     */
+    public function __construct(AssetUrlGeneratorInterface $generator, $locations = array())
+    {
+        $this->generator = $generator;
+
+        // Strip slashes from location paths.
+        foreach ($locations as $name => $path) {
+            $this->locations[$name] = trim($path, '/');
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAssetUrlGenerator()
+    {
+        return $this->generator;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setAssetUrlGenerator(AssetUrlGeneratorInterface $generator)
+    {
+        $this->generator = $generator;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        $parsed_args = $template->parseArguments($args);
+        if (empty($parsed_args)) {
+            return '';
+        }
+        $relative_path = $context->get($parsed_args[0]);
+
+        if (preg_match("/^@(\w+)\//", $relative_path, $matches)) {
+            // Resolve locations
+            $relative_path = substr_replace(
+                $relative_path,
+                $this->resolveLocation($matches[1]),
+                0,
+                strlen($matches[0]) - 1 // Leave the slash in place
+            );
+        }
+
+        return $this->generator->generate($relative_path);
+    }
+
+    /**
+     * Resolves location by it's name
+     *
+     * @param string $name Location name
+     * @return string Relative path of the location.
+     * @throws \InvalidArgumentException
+     */
+    protected function resolveLocation($name)
+    {
+        foreach ($this->locations as $current_name => $location) {
+            if ($name == $current_name) {
+                return $location;
+            }
+        }
+
+        throw new \InvalidArgumentException(sprintf('Unknown location %s', $name));
+    }
+}