From f9dd5b2f5746e360d28c36d843c59ee475b936c4 Mon Sep 17 00:00:00 2001
From: Samuel Georges <sam@daftspunk.com>
Date: Fri, 21 Oct 2016 07:15:08 +1100
Subject: [PATCH] Plugins can now define custom list column types

---
 modules/backend/widgets/Lists.php        | 26 ++++++++++++++++++++
 modules/system/classes/PluginBase.php    | 10 ++++++++
 modules/system/classes/PluginManager.php | 30 ++++++++++++++++++++++++
 3 files changed, 66 insertions(+)

diff --git a/modules/backend/widgets/Lists.php b/modules/backend/widgets/Lists.php
index fece182ea..1bd0434c0 100644
--- a/modules/backend/widgets/Lists.php
+++ b/modules/backend/widgets/Lists.php
@@ -12,6 +12,7 @@ use Carbon\Carbon;
 use October\Rain\Html\Helper as HtmlHelper;
 use October\Rain\Router\Helper as RouterHelper;
 use System\Helpers\DateTime as DateTimeHelper;
+use System\Classes\PluginManager;
 use Backend\Classes\ListColumn;
 use Backend\Classes\WidgetBase;
 use ApplicationException;
@@ -825,6 +826,9 @@ class Lists extends WidgetBase
         if (method_exists($this, 'eval'. studly_case($column->type) .'TypeValue')) {
             $value = $this->{'eval'. studly_case($column->type) .'TypeValue'}($record, $column, $value);
         }
+        else {
+            $value = $this->evalCustomListType($column->type, $record, $column, $value);
+        }
 
         /*
          * Apply default value.
@@ -874,6 +878,28 @@ class Lists extends WidgetBase
     // Value processing
     //
 
+    /**
+     * Process a custom list types registered by plugins.
+     */
+    protected function evalCustomListType($type, $record, $column, $value)
+    {
+        $plugins = PluginManager::instance()->getRegistrationMethodValues('registerListColumnTypes');
+
+        foreach ($plugins as $availableTypes) {
+            if (!isset($availableTypes[$type])) {
+                continue;
+            }
+
+            $callback = $availableTypes[$type];
+
+            if (is_callable($callback)) {
+                return call_user_func_array($callback, [$value, $column, $record]);
+            }
+        }
+
+        throw new ApplicationException(sprintf('List column type "%s" could not be found.', $type));
+    }
+
     /**
      * Process as text, escape the value
      */
diff --git a/modules/system/classes/PluginBase.php b/modules/system/classes/PluginBase.php
index fbfe12c5c..279033d41 100644
--- a/modules/system/classes/PluginBase.php
+++ b/modules/system/classes/PluginBase.php
@@ -181,6 +181,16 @@ class PluginBase extends ServiceProviderBase
         return [];
     }
 
+    /**
+     * Registers custom back-end list column types introduced by this plugin.
+     *
+     * @return array
+     */
+    public function registerListColumnTypes()
+    {
+        return [];
+    }
+
     /**
      * Registers any mail templates implemented by this plugin.
      * The templates must be returned in the following format:
diff --git a/modules/system/classes/PluginManager.php b/modules/system/classes/PluginManager.php
index adb16b51e..24c362461 100644
--- a/modules/system/classes/PluginManager.php
+++ b/modules/system/classes/PluginManager.php
@@ -55,6 +55,11 @@ class PluginManager
      */
     protected $disabledPlugins = [];
 
+    /**
+     * @var array Cache of registration method results.
+     */
+    protected $registrationMethodCache = [];
+
     /**
      * @var boolean Prevent all plugins from registering or booting
      */
@@ -418,6 +423,31 @@ class PluginManager
         return $identifier;
     }
 
+    /**
+     * Spins over every plugin object and collects the results of a method call.
+     * @param  string $methodName
+     * @return array
+     */
+    public function getRegistrationMethodValues($methodName)
+    {
+        if (isset($this->registrationMethodCache[$methodName])) {
+            return $this->registrationMethodCache[$methodName];
+        }
+
+        $results = [];
+        $plugins = $this->getPlugins();
+
+        foreach ($plugins as $id => $plugin) {
+            if (!method_exists($plugin, $methodName)) {
+                continue;
+            }
+
+            $results[$id] = $plugin->{$methodName}();
+        }
+
+        return $this->registrationMethodCache[$methodName] = $results;
+    }
+
     //
     // Disability
     //