From b70c7b141f2fa30decac588d8d46cb94d97f32e7 Mon Sep 17 00:00:00 2001
From: Ilya Tregubov <ilya@moodle.com>
Date: Tue, 8 Aug 2023 15:51:24 +0800
Subject: [PATCH] MDL-43820 enrol_self: Override find_instance

This one is bit tricky. find_instance will find first available since
results are not unique...
---
 enrol/self/lib.php             | 22 ++++++++++++++++++++++
 enrol/self/tests/self_test.php | 28 ++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/enrol/self/lib.php b/enrol/self/lib.php
index 7793ccb9f1a..ab838958b3c 100644
--- a/enrol/self/lib.php
+++ b/enrol/self/lib.php
@@ -1088,6 +1088,28 @@ class enrol_self_plugin extends enrol_plugin {
     public function is_csv_upload_supported(): bool {
         return true;
     }
+
+    /**
+     * Finds matching instances for a given course.
+     *
+     * @param array $enrolmentdata enrolment data.
+     * @param int $courseid Course ID.
+     * @return stdClass|null Matching instance
+     */
+    public function find_instance(array $enrolmentdata, int $courseid) : ?stdClass {
+
+        $instances = enrol_get_instances($courseid, false);
+        $instance = null;
+        foreach ($instances as $i) {
+            if ($i->enrol == 'self') {
+                // This is bad - we can not really distinguish between self instances. So grab first available.
+                $instance = $i;
+                break;
+            }
+        }
+        return $instance;
+    }
+
 }
 
 /**
diff --git a/enrol/self/tests/self_test.php b/enrol/self/tests/self_test.php
index 351fdfeec34..53d2cc82d86 100644
--- a/enrol/self/tests/self_test.php
+++ b/enrol/self/tests/self_test.php
@@ -961,4 +961,32 @@ class self_test extends \advanced_testcase {
         // Self enrol has 2 enrol actions -- edit and unenrol.
         $this->assertCount(2, $actions);
     }
+
+    /**
+     * Test the behaviour of find_instance().
+     *
+     * @covers ::find_instance
+     */
+    public function test_find_instance() {
+        global $DB;
+        $this->resetAfterTest();
+
+        $cat = $this->getDataGenerator()->create_category();
+        // When we create a course, a self enrolment instance is also created.
+        $course = $this->getDataGenerator()->create_course(['category' => $cat->id, 'shortname' => 'ANON']);
+
+        $teacherrole = $DB->get_record('role', ['shortname' => 'teacher']);
+        $selfplugin = enrol_get_plugin('self');
+
+        $instanceid1 = $DB->get_record('enrol', ['courseid' => $course->id, 'enrol' => 'self']);
+
+        // Let's add a second instance.
+        $instanceid2 = $selfplugin->add_instance($course, ['roleid' => $teacherrole->id]);
+
+        $enrolmentdata = [];
+        // The first instance should be returned - due to sorting in enrol_get_instances().
+        $actual = $selfplugin->find_instance($enrolmentdata, $course->id);
+        $this->assertEquals($instanceid1->id, $actual->id);
+    }
+
 }