class TestSuiteLoader

final class TestSuiteLoader {
    
    /**
     * @psalm-var list<class-string>
     */
    private static array $declaredClasses = [];
    
    /**
     * @psalm-var array<non-empty-string, list<class-string>>
     */
    private static array $fileToClassesMap = [];
    
    /**
     * @throws Exception
     */
    public function load(string $suiteClassFile) : ReflectionClass {
        $suiteClassFile = realpath($suiteClassFile);
        $suiteClassName = $this->classNameFromFileName($suiteClassFile);
        $loadedClasses = $this->loadSuiteClassFile($suiteClassFile);
        foreach ($loadedClasses as $className) {
            
            /** @noinspection PhpUnhandledExceptionInspection */
            $class = new ReflectionClass($className);
            if ($class->isAnonymous()) {
                continue;
            }
            if ($class->getFileName() !== $suiteClassFile) {
                continue;
            }
            if (!$class->isSubclassOf(TestCase::class)) {
                continue;
            }
            if (!str_ends_with(strtolower($class->getShortName()), strtolower($suiteClassName))) {
                continue;
            }
            if (!$class->isAbstract()) {
                return $class;
            }
            $e = new ClassIsAbstractException($class->getName(), $suiteClassFile);
        }
        if (isset($e)) {
            throw $e;
        }
        foreach ($loadedClasses as $className) {
            if (str_ends_with(strtolower($className), strtolower($suiteClassName))) {
                throw new ClassDoesNotExtendTestCaseException($className, $suiteClassFile);
            }
        }
        throw new ClassCannotBeFoundException($suiteClassName, $suiteClassFile);
    }
    private function classNameFromFileName(string $suiteClassFile) : string {
        $className = basename($suiteClassFile, '.php');
        $dotPos = strpos($className, '.');
        if ($dotPos !== false) {
            $className = substr($className, 0, $dotPos);
        }
        return $className;
    }
    
    /**
     * @psalm-return list<class-string>
     */
    private function loadSuiteClassFile(string $suiteClassFile) : array {
        if (isset(self::$fileToClassesMap[$suiteClassFile])) {
            return self::$fileToClassesMap[$suiteClassFile];
        }
        if (empty(self::$declaredClasses)) {
            self::$declaredClasses = get_declared_classes();
        }
        require_once $suiteClassFile;
        $loadedClasses = array_values(array_diff(get_declared_classes(), self::$declaredClasses));
        foreach ($loadedClasses as $loadedClass) {
            
            /** @noinspection PhpUnhandledExceptionInspection */
            $class = new ReflectionClass($loadedClass);
            if (!isset(self::$fileToClassesMap[$class->getFileName()])) {
                self::$fileToClassesMap[$class->getFileName()] = [];
            }
            self::$fileToClassesMap[$class->getFileName()][] = $class->getName();
        }
        self::$declaredClasses = get_declared_classes();
        if (empty($loadedClasses)) {
            return self::$declaredClasses;
        }
        return $loadedClasses;
    }

}