From cb38961988473decaca3a18a10b42a8aad0dcb5c Mon Sep 17 00:00:00 2001
From: Jake Dallimore <jake@moodle.com>
Date: Fri, 23 Nov 2018 12:28:06 +0800
Subject: [PATCH] MDL-64167 core_message: get_conversations() handles self
 conversations

Those individual conversations created with one's self (via admin user
bulk actions) are now supported in get_conversations(). These had two
records with the same userid in the message_conversation_members table.
The following adjustments have been made to accomodate these:
- Member count adjusted to read 1, not 2 for 'self' conversations.
- Member information for the current user now returned for 'self'
conversations.
- The method now tracks 'self' conversations via $selfconversations.
---
 message/classes/api.php | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/message/classes/api.php b/message/classes/api.php
index d5792239e13..776ca9248c2 100644
--- a/message/classes/api.php
+++ b/message/classes/api.php
@@ -586,6 +586,7 @@ class api {
         $conversationset = $DB->get_recordset_sql($sql, $params, $limitfrom, $limitnum);
 
         $conversations = [];
+        $selfconversations = []; // Used to track legacy conversations with one's self (both conv members the same user).
         $members = [];
         $individualmembers = [];
         $groupmembers = [];
@@ -613,6 +614,9 @@ class api {
         //
         // For 'individual' type conversations between 2 users, regardless of who sent the last message,
         // we want the details of the other member in the conversation (i.e. not the current user).
+        // The only exception to the 'not the current user' rule is for 'self' conversations - a legacy construct in which a user
+        // can message themselves via user bulk actions. Subsequently, there are 2 records for the same user created in the members
+        // table.
         //
         // For 'group' type conversations, we want the details of the member who sent the last message, if there is one.
         // This can be the current user or another group member, but for groups without messages, this will be empty.
@@ -654,6 +658,23 @@ class api {
                 $members[$member->conversationid][$member->userid] = $member->userid;
                 $individualmembers[$member->userid] = $member->userid;
             }
+
+            // Self conversations: If any of the individual conversations which were missing members are still missing members,
+            // we know these must be 'self' conversations. This is a legacy scenario, created via user bulk actions.
+            // In such cases, the member returned should be the current user.
+            //
+            // NOTE: Currently, these conversations are not returned by this method, however,
+            // identifying them is important for future reference.
+            foreach ($individualconversations as $indconvid) {
+                if (empty($members[$indconvid])) {
+                    // Keep track of the self conversation (for future use).
+                    $selfconversations[$indconvid] = $indconvid;
+
+                    // Set the member to the current user.
+                    $members[$indconvid][$userid] = $userid;
+                    $individualmembers[$userid] = $userid;
+                }
+            }
         }
 
         // We could fail early here if we're sure that:
@@ -702,7 +723,7 @@ class api {
         // MEMBER COUNT.
         $cids = array_column($conversations, 'id');
         list ($cidinsql, $cidinparams) = $DB->get_in_or_equal($cids, SQL_PARAMS_NAMED, 'convid');
-        $membercountsql = "SELECT conversationid, count(id) AS membercount
+        $membercountsql = "SELECT conversationid, count(DISTINCT userid) AS membercount
                              FROM {message_conversation_members} mcm
                             WHERE mcm.conversationid $cidinsql
                          GROUP BY mcm.conversationid";
-- 
2.17.1