From b9df5bbbf029d9005dad7dabd4be774207e85791 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A1t=C3=A9=20Bartus?= <mate.bartus@gmail.com>
Date: Sun, 1 Jun 2025 11:37:12 +0100
Subject: [PATCH] [ticket/17516] Remove dependency on topological sort library

PHPBB-17516
---
 phpBB/composer.json                           |  1 -
 phpBB/composer.lock                           | 43 ------------
 phpBB/phpbb/db/migration/schema_generator.php | 68 +++++++++++++------
 3 files changed, 48 insertions(+), 64 deletions(-)

diff --git a/phpBB/composer.json b/phpBB/composer.json
index c75912664b..6c2288bcd2 100644
--- a/phpBB/composer.json
+++ b/phpBB/composer.json
@@ -33,7 +33,6 @@
 		"ext-sodium": "*",
 		"bantu/ini-get-wrapper": "~1.0",
 		"carlos-mg89/oauth": "^0.8.15",
-		"chita/topological_sort": "^3.0",
 		"composer/composer": "^2.0",
 		"composer/installers": "^1.9",
 		"composer/package-versions-deprecated": "^1.11",
diff --git a/phpBB/composer.lock b/phpBB/composer.lock
index a353e9409b..1dd732fb45 100644
--- a/phpBB/composer.lock
+++ b/phpBB/composer.lock
@@ -171,49 +171,6 @@
             },
             "time": "2025-02-08T12:14:07+00:00"
         },
-        {
-            "name": "chita/topological_sort",
-            "version": "v3.0.1",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/CHItA/TopologicalSort.git",
-                "reference": "9e0401c712d0c7cf012f264cc105669844d2479e"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/CHItA/TopologicalSort/zipball/9e0401c712d0c7cf012f264cc105669844d2479e",
-                "reference": "9e0401c712d0c7cf012f264cc105669844d2479e",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=7.1.0"
-            },
-            "require-dev": {
-                "phpunit/phpunit": "^7.0"
-            },
-            "type": "library",
-            "autoload": {
-                "psr-4": {
-                    "CHItA\\TopologicalSort\\": "src/"
-                }
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Máté Bartus",
-                    "email": "mate.bartus@gmail.com"
-                }
-            ],
-            "description": "Topological sort function",
-            "support": {
-                "issues": "https://github.com/CHItA/TopologicalSort/issues",
-                "source": "https://github.com/CHItA/TopologicalSort/tree/v3.0.1"
-            },
-            "time": "2021-01-04T21:31:59+00:00"
-        },
         {
             "name": "composer/ca-bundle",
             "version": "1.5.6",
diff --git a/phpBB/phpbb/db/migration/schema_generator.php b/phpBB/phpbb/db/migration/schema_generator.php
index 0048d8198d..ce07c30d45 100644
--- a/phpBB/phpbb/db/migration/schema_generator.php
+++ b/phpBB/phpbb/db/migration/schema_generator.php
@@ -14,21 +14,17 @@
 namespace phpbb\db\migration;
 
 use Closure;
-use LogicException;
 use phpbb\config\config;
 use phpbb\db\driver\driver_interface;
 use phpbb\db\migrator;
 use phpbb\db\tools\tools_interface;
 use UnexpectedValueException;
-use CHItA\TopologicalSort\TopologicalSort;
 
 /**
 * The schema generator generates the schema based on the existing migrations
 */
 class schema_generator
 {
-	use TopologicalSort;
-
 	/** @var config */
 	protected $config;
 
@@ -103,24 +99,56 @@ class schema_generator
 			return $this->tables;
 		}
 
-		$migrations = $this->class_names;
-		$filter = function($class_name) {
-			return !migrator::is_migration($class_name);
-		};
-
-		$edges = function($class_name) {
-			return $class_name::depends_on();
-		};
-
-		$apply_for_each = function($class_name) {
-			$this->apply_migration_to_schema($class_name);
-		};
-
-		try
+		$dependency_counts = [];
+		$dependencies = [];
+		$applicable_migrations = [];
+		$migration_count = 0;
+		foreach ($this->class_names as $class_name)
 		{
-			$this->topologicalSort($migrations, $edges, true, $apply_for_each, $filter);
+			if (!migrator::is_migration($class_name))
+			{
+				continue;
+			}
+
+			$migration_count++;
+			$migration_dependencies = $class_name::depends_on();
+			if (empty($migration_dependencies))
+			{
+				$applicable_migrations[] = $class_name;
+				continue;
+			}
+
+			$dependency_counts[$class_name] = count($migration_dependencies);
+			foreach ($migration_dependencies as $migration_dependency)
+			{
+				$dependencies[$migration_dependency][] = $class_name;
+			}
 		}
-		catch (LogicException $e)
+
+		$applied_migrations = 0;
+		while (!empty($applicable_migrations))
+		{
+			$migration = array_pop($applicable_migrations);
+			$this->apply_migration_to_schema($migration);
+			++$applied_migrations;
+
+			if (!array_key_exists($migration, $dependencies))
+			{
+				continue;
+			}
+
+			$dependents = $dependencies[$migration];
+			foreach ($dependents as $dependent)
+			{
+				$dependency_counts[$dependent]--;
+				if ($dependency_counts[$dependent] === 0)
+				{
+					$applicable_migrations[] = $dependent;
+				}
+			}
+		}
+
+		if ($migration_count !== $applied_migrations)
 		{
 			throw new UnexpectedValueException(
 				"Migrations either have circular dependencies or unsatisfiable dependencies."