From dfbf50e18be8d0ac6d94d06ac6cefeff0e87c363 Mon Sep 17 00:00:00 2001
From: Shamim Rezaie <shamim@moodle.com>
Date: Fri, 19 Feb 2021 02:43:30 +1100
Subject: [PATCH] MDL-70816 core: Activity date details base class

* Base class for fetching an activity module's important date for a user
---
 lib/classes/activity_dates.php | 101 +++++++++++++++++++++++++++++++++
 1 file changed, 101 insertions(+)
 create mode 100644 lib/classes/activity_dates.php

diff --git a/lib/classes/activity_dates.php b/lib/classes/activity_dates.php
new file mode 100644
index 00000000000..74564e0f68d
--- /dev/null
+++ b/lib/classes/activity_dates.php
@@ -0,0 +1,101 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Contains the base class for fetching the important dates in an activity module for a given module instance and a user.
+ *
+ * @package   core
+ * @copyright Shamim Rezaie <shamim@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+declare(strict_types=1);
+
+namespace core;
+
+use cm_info;
+
+/**
+ * Class for fetching the  important dates of an activity module for a given module instance and a user.
+ *
+ * @copyright Shamim Rezaie <shamim@moodle.com>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+abstract class activity_dates {
+
+    /**
+     * @var cm_info The course module information object.
+     */
+    protected $cm;
+
+    /**
+     * @var int The user id.
+     */
+    protected $userid;
+
+    /**
+     * activity_dates constructor.
+     *
+     * @param cm_info $cm course module
+     * @param int $userid user id
+     */
+    public function __construct(cm_info $cm, int $userid) {
+        $this->cm = $cm;
+        $this->userid = $userid;
+    }
+
+    /**
+     * Returns a list of important dates in the given module for the user.
+     *
+     * @param cm_info $cm The course module information.
+     * @param int $userid The user ID.
+     * @return array|array[]
+     */
+    public static function get_dates_for_module(cm_info $cm, int $userid): array {
+        $cmdatesclassname = static::get_dates_classname($cm->modname);
+        if (!$cmdatesclassname) {
+            return [];
+        }
+
+        /** @var activity_dates $dates */
+        $dates = new $cmdatesclassname($cm, $userid);
+        return $dates->get_dates();
+    }
+
+    /**
+     * Fetches the module's dates class implementation if it's available.
+     *
+     * @param string $modname The activity module name. Usually from cm_info::modname.
+     * @return string|null
+     */
+    private static function get_dates_classname(string $modname): ?string {
+        $cmdatesclass = "mod_{$modname}\\dates";
+        if (class_exists($cmdatesclass) && is_subclass_of($cmdatesclass, self::class)) {
+            return $cmdatesclass;
+        }
+
+        return null;
+    }
+
+    /**
+     * Returns a list of important dates for this module.
+     *
+     * @return array[] Each element of the array is an array with keys:
+     *                 label - The label for the date
+     *                 timestamp - The date
+     */
+    protected abstract function get_dates(): array;
+}