From 9b8058463b3b7f931bec02bf0cbd5bc4dfee2df5 Mon Sep 17 00:00:00 2001
From: Mohammad Farouk <phun.for.physics@gmail.com>
Date: Thu, 3 Oct 2024 01:35:11 +0300
Subject: [PATCH] Fix bug for debit

---
 classes/util/balance_op.php    | 15 ++++++----
 tests/util/balance_op_test.php | 55 ++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+), 6 deletions(-)

diff --git a/classes/util/balance_op.php b/classes/util/balance_op.php
index 7b0cee65..1be628d4 100644
--- a/classes/util/balance_op.php
+++ b/classes/util/balance_op.php
@@ -188,20 +188,21 @@ protected function cut_from_main($amount) {
         $nonrefundable = $this->details['mainnonrefund'];
         $free = $this->details['mainfree'] ?? 0;
         if ($refundable >= $amount) {
-            $refundable = $refundable - $amount;
+            $refundable -= $amount;
         } else {
             $remain = $amount - $refundable;
             $refundable = 0;
             if ($remain > $nonrefundable) {
-                $nonrefundable = 0;
                 $refundable = $nonrefundable - $remain;
+                $nonrefundable = 0;
             } else {
-                $nonrefundable = $nonrefundable - $remain;
+                $nonrefundable -= $remain;
             }
 
             $newfree = max($free - $remain, 0);
             $this->freecut += $free - $newfree;
         }
+
         $this->details['mainrefundable'] = $refundable;
         $this->details['mainnonrefund'] = $nonrefundable;
         $this->details['mainbalance'] = $refundable + $nonrefundable;
@@ -275,6 +276,7 @@ protected function add_to_main($amount, $refundable, $free = false) {
      */
     public function debit($amount, $for = self::USER, $thingid = 0, $desc = '', $neg = false) {
         global $DB, $USER;
+
         if ($for == self::USER) {
             $charger = !empty($thingid) ? $thingid : $USER->id;
         } else {
@@ -300,6 +302,7 @@ public function debit($amount, $for = self::USER, $thingid = 0, $desc = '', $neg
             $response = $wordpress->debit($this->userid, $amount, $desc, $charger);
 
             if (!is_numeric($response)) {
+                debugging($response);
                 return false;
             }
 
@@ -344,8 +347,8 @@ public function debit($amount, $for = self::USER, $thingid = 0, $desc = '', $neg
         }
 
         // No debit occurs.
-        if ($newbalance != $before - $amount) {
-            debugging("no debit occur");
+        if ($newbalance != ($before - $amount)) {
+            throw new \moodle_exception('Error while debiting');
         }
 
         $recorddata = [
@@ -367,7 +370,6 @@ public function debit($amount, $for = self::USER, $thingid = 0, $desc = '', $neg
         (new notifications)->transaction_notify($recorddata);
 
         $this->trigger_transaction_event('debit', $charger, $description, false);
-
         return true;
     }
 
@@ -463,6 +465,7 @@ private function get_debit_description($for, $thingid, $desc) {
      */
     public function credit($amount, $by = self::OTHER, $thingid = 0, $desc = '', $refundable = true, $trigger = true) {
         global $DB;
+
         if (in_array($by, [self::USER, self::C_TRANSFER, self::C_REFERRAL])) {
             $charger = $thingid;
         } else {
diff --git a/tests/util/balance_op_test.php b/tests/util/balance_op_test.php
index 3058dc2d..9c546cd6 100644
--- a/tests/util/balance_op_test.php
+++ b/tests/util/balance_op_test.php
@@ -1099,7 +1099,62 @@ private function reset_balance($userid): void {
                 $op->debit($op->get_valid_balance(), $op::OTHER);
             }
         }
+
         $balance = new balance($userid);
         $this->assertEquals(0, $balance->get_total_balance());
     }
+
+    /**
+     * Test if multiple transactions in one call will behave.
+     * @return void
+     */
+    public function test_multiple_transactions(): void {
+        global $CFG, $DB;
+        $this->resetAfterTest();
+        $user = $this->getDataGenerator()->create_user();
+        $this->setUser($user);
+
+        $op = new balance_op($user->id);
+        $op->credit(100, refundable: false);
+        $op->credit(50, refundable: false);
+        $op->debit(100);
+        $op->credit(50, refundable: false);
+
+        $op = new balance_op($user->id);
+        $op->debit(50);
+        $op->credit(100, refundable: false);
+        $op->credit(amount: 100, refundable: false);
+        $op->credit(amount: 30, refundable: false);
+        $op->debit(20);
+
+        $this->assertEquals(260, $op->get_total_balance());
+        $this->assertEquals(260, $op->get_valid_balance());
+        $this->assertEquals(260, $op->get_main_balance());
+
+        $op = new balance_op($user->id);
+        $this->assertEquals(260, $op->get_total_balance());
+        $this->assertEquals(260, $op->get_valid_balance());
+        $this->assertEquals(260, $op->get_main_balance());
+
+        purge_caches();
+        purge_all_caches();
+
+        $op = new balance_op($user->id);
+        $this->assertEquals(260, $op->get_total_balance());
+        $this->assertEquals(260, $op->get_valid_balance());
+        $this->assertEquals(260, $op->get_main_balance());
+
+        $op->debit(560, $op::USER, 0, '', true);
+        $op->debit(100, $op::USER, 0, '', true);
+        $op->debit(30, $op::USER, 0, '', true);
+        $op = new balance_op($user->id);
+        $op->debit(40, $op::USER, 0, '', true);
+        $op->debit(50, $op::USER, 0, '', true);
+        $op->debit(60, $op::USER, 0, '', true);
+
+        $op = new balance_op($user->id);
+        $this->assertEquals(-580, $op->get_total_balance());
+        $this->assertEquals(-580, $op->get_valid_balance());
+        $this->assertEquals(-580, $op->get_main_balance());
+    }
 }