Add the possibility to attach template hooks with a callback

ChangeLog

@@ -3,7 +3,7 @@ Version 1.0.33 (unreleased)
 
 Improvements:
 
-* Add the possibility to attach template hooks with local variables
+* Add the possibility to attach template hooks with local variables and callback
 * Add "reference" hooks
 * Show project name in task forms
 * Convert vanilla CSS to SASS

app/Helper/HookHelper.php

@@ -46,6 +46,12 @@ class HookHelper extends Base
         foreach ($this->hook->getListeners($hook) as $params) {
             if (! empty($params['variables'])) {
                 $variables = array_merge($variables, $params['variables']);
+            } elseif (! empty($params['callable'])) {
+                $result = call_user_func_array($params['callable'], $variables);
+
+                if (is_array($result)) {
+                    $variables = array_merge($variables, $result);
+                }
             }
 
             $buffer .= $this->template->render($params['template'], $variables);
@@ -72,4 +78,25 @@ class HookHelper extends Base
 
         return $this;
     }
+
+    /**
+     * Attach a template to a hook with a callable
+     *
+     * Arguments passed to the callback are the one passed to the hook
+     *
+     * @access public
+     * @param  string   $hook
+     * @param  string   $template
+     * @param  callable $callable
+     * @return $this
+     */
+    public function attachCallable($hook, $template, callable $callable)
+    {
+        $this->hook->on($hook, array(
+            'template' => $template,
+            'callable' => $callable,
+        ));
+
+        return $this;
+    }
 }

doc/plugin-hooks.markdown

@@ -161,6 +161,14 @@ $this->template->hook->attach('template:dashboard:sidebar', 'myplugin:dashboard/
 ));
 ```
 
+Example to attach a template with a callable:
+
+```php
+$this->template->hook->attach('template:dashboard:sidebar', 'myplugin:dashboard/sidebar', function($hook_param1, $hook_param2) {
+    return array('new_template_variable' => 'foobar'); // Inject a new variable into the plugin template
+});
+```
+
 This call is usually defined in the `initialize()` method.
 The first argument is name of the hook and the second argument is the template name.
 

tests/units/Helper/HookHelperTest.php

@@ -6,6 +6,57 @@ use Kanboard\Helper\HookHelper;
 
 class HookHelperTest extends Base
 {
+    public function testAttachCallable()
+    {
+        $this->container['template'] = $this
+            ->getMockBuilder('\Kanboard\Core\Template')
+            ->setConstructorArgs(array($this->container['helper']))
+            ->setMethods(array('render'))
+            ->getMock();
+
+        $this->container['template']
+            ->expects($this->once())
+            ->method('render')
+            ->with(
+                $this->equalTo('tpl1'),
+                $this->equalTo(array('k0' => 'v0', 'k1' => 'v1'))
+            )
+            ->will($this->returnValue('tpl1_content'));
+
+        $hookHelper = new HookHelper($this->container);
+        $hookHelper->attachCallable('test', 'tpl1', function() {
+            return array(
+                'k1' => 'v1',
+            );
+        });
+
+        $this->assertEquals('tpl1_content', $hookHelper->render('test', array('k0' => 'v0')));
+    }
+
+    public function testAttachCallableWithNoResult()
+    {
+        $this->container['template'] = $this
+            ->getMockBuilder('\Kanboard\Core\Template')
+            ->setConstructorArgs(array($this->container['helper']))
+            ->setMethods(array('render'))
+            ->getMock();
+
+        $this->container['template']
+            ->expects($this->once())
+            ->method('render')
+            ->with(
+                $this->equalTo('tpl1'),
+                $this->equalTo(array('k0' => 'v0'))
+            )
+            ->will($this->returnValue('tpl1_content'));
+
+        $hookHelper = new HookHelper($this->container);
+        $hookHelper->attachCallable('test', 'tpl1', function() {
+        });
+
+        $this->assertEquals('tpl1_content', $hookHelper->render('test', array('k0' => 'v0')));
+    }
+
     public function testAttachLocalVariables()
     {
         $this->container['template'] = $this