class TestSuiteSorter

final class TestSuiteSorter {
    
    /**
     * @var int
     */
    public const ORDER_DEFAULT = 0;
    
    /**
     * @var int
     */
    public const ORDER_RANDOMIZED = 1;
    
    /**
     * @var int
     */
    public const ORDER_REVERSED = 2;
    
    /**
     * @var int
     */
    public const ORDER_DEFECTS_FIRST = 3;
    
    /**
     * @var int
     */
    public const ORDER_DURATION = 4;
    
    /**
     * @var int
     */
    public const ORDER_SIZE = 5;
    private const SIZE_SORT_WEIGHT = [
        'small' => 1,
        'medium' => 2,
        'large' => 3,
        'unknown' => 4,
    ];
    
    /**
     * @psalm-var array<string, int> Associative array of (string => DEFECT_SORT_WEIGHT) elements
     */
    private array $defectSortOrder = [];
    private readonly ResultCache $cache;
    
    /**
     * @psalm-var array<string> A list of normalized names of tests before reordering
     */
    private array $originalExecutionOrder = [];
    
    /**
     * @psalm-var array<string> A list of normalized names of tests affected by reordering
     */
    private array $executionOrder = [];
    public function __construct(?ResultCache $cache = null) {
        $this->cache = $cache ?? new NullResultCache();
    }
    
    /**
     * @throws Exception
     */
    public function reorderTestsInSuite(Test $suite, int $order, bool $resolveDependencies, int $orderDefects, bool $isRootTestSuite = true) : void {
        $allowedOrders = [
            self::ORDER_DEFAULT,
            self::ORDER_REVERSED,
            self::ORDER_RANDOMIZED,
            self::ORDER_DURATION,
            self::ORDER_SIZE,
        ];
        if (!in_array($order, $allowedOrders, true)) {
            throw new InvalidOrderException();
        }
        $allowedOrderDefects = [
            self::ORDER_DEFAULT,
            self::ORDER_DEFECTS_FIRST,
        ];
        if (!in_array($orderDefects, $allowedOrderDefects, true)) {
            throw new InvalidOrderException();
        }
        if ($isRootTestSuite) {
            $this->originalExecutionOrder = $this->calculateTestExecutionOrder($suite);
        }
        if ($suite instanceof TestSuite) {
            foreach ($suite as $_suite) {
                $this->reorderTestsInSuite($_suite, $order, $resolveDependencies, $orderDefects, false);
            }
            if ($orderDefects === self::ORDER_DEFECTS_FIRST) {
                $this->addSuiteToDefectSortOrder($suite);
            }
            $this->sort($suite, $order, $resolveDependencies, $orderDefects);
        }
        if ($isRootTestSuite) {
            $this->executionOrder = $this->calculateTestExecutionOrder($suite);
        }
    }
    public function getOriginalExecutionOrder() : array {
        return $this->originalExecutionOrder;
    }
    public function getExecutionOrder() : array {
        return $this->executionOrder;
    }
    private function sort(TestSuite $suite, int $order, bool $resolveDependencies, int $orderDefects) : void {
        if (empty($suite->tests())) {
            return;
        }
        if ($order === self::ORDER_REVERSED) {
            $suite->setTests($this->reverse($suite->tests()));
        }
        elseif ($order === self::ORDER_RANDOMIZED) {
            $suite->setTests($this->randomize($suite->tests()));
        }
        elseif ($order === self::ORDER_DURATION) {
            $suite->setTests($this->sortByDuration($suite->tests()));
        }
        elseif ($order === self::ORDER_SIZE) {
            $suite->setTests($this->sortBySize($suite->tests()));
        }
        if ($orderDefects === self::ORDER_DEFECTS_FIRST) {
            $suite->setTests($this->sortDefectsFirst($suite->tests()));
        }
        if ($resolveDependencies && !$suite instanceof DataProviderTestSuite) {
            $tests = $suite->tests();
            $suite->setTests($this->resolveDependencies($tests));
        }
    }
    private function addSuiteToDefectSortOrder(TestSuite $suite) : void {
        $max = 0;
        foreach ($suite->tests() as $test) {
            if (!$test instanceof Reorderable) {
                continue;
            }
            if (!isset($this->defectSortOrder[$test->sortId()])) {
                $this->defectSortOrder[$test->sortId()] = $this->cache
                    ->status($test->sortId())
                    ->asInt();
                $max = max($max, $this->defectSortOrder[$test->sortId()]);
            }
        }
        $this->defectSortOrder[$suite->sortId()] = $max;
    }
    private function reverse(array $tests) : array {
        return array_reverse($tests);
    }
    private function randomize(array $tests) : array {
        shuffle($tests);
        return $tests;
    }
    private function sortDefectsFirst(array $tests) : array {
        usort($tests, fn($left, $right) => $this->cmpDefectPriorityAndTime($left, $right));
        return $tests;
    }
    private function sortByDuration(array $tests) : array {
        usort($tests, fn($left, $right) => $this->cmpDuration($left, $right));
        return $tests;
    }
    private function sortBySize(array $tests) : array {
        usort($tests, fn($left, $right) => $this->cmpSize($left, $right));
        return $tests;
    }
    
    /**
     * Comparator callback function to sort tests for "reach failure as fast as possible".
     *
     * 1. sort tests by defect weight defined in self::DEFECT_SORT_WEIGHT
     * 2. when tests are equally defective, sort the fastest to the front
     * 3. do not reorder successful tests
     */
    private function cmpDefectPriorityAndTime(Test $a, Test $b) : int {
        if (!($a instanceof Reorderable && $b instanceof Reorderable)) {
            return 0;
        }
        $priorityA = $this->defectSortOrder[$a->sortId()] ?? 0;
        $priorityB = $this->defectSortOrder[$b->sortId()] ?? 0;
        if ($priorityB <=> $priorityA) {
            // Sort defect weight descending
            return $priorityB <=> $priorityA;
        }
        if ($priorityA || $priorityB) {
            return $this->cmpDuration($a, $b);
        }
        // do not change execution order
        return 0;
    }
    
    /**
     * Compares test duration for sorting tests by duration ascending.
     */
    private function cmpDuration(Test $a, Test $b) : int {
        if (!($a instanceof Reorderable && $b instanceof Reorderable)) {
            return 0;
        }
        return $this->cache
            ->time($a->sortId()) <=> $this->cache
            ->time($b->sortId());
    }
    
    /**
     * Compares test size for sorting tests small->medium->large->unknown.
     */
    private function cmpSize(Test $a, Test $b) : int {
        $sizeA = $a instanceof TestCase || $a instanceof DataProviderTestSuite ? $a->size()
            ->asString() : 'unknown';
        $sizeB = $b instanceof TestCase || $b instanceof DataProviderTestSuite ? $b->size()
            ->asString() : 'unknown';
        return self::SIZE_SORT_WEIGHT[$sizeA] <=> self::SIZE_SORT_WEIGHT[$sizeB];
    }
    
    /**
     * Reorder Tests within a TestCase in such a way as to resolve as many dependencies as possible.
     * The algorithm will leave the tests in original running order when it can.
     * For more details see the documentation for test dependencies.
     *
     * Short description of algorithm:
     * 1. Pick the next Test from remaining tests to be checked for dependencies.
     * 2. If the test has no dependencies: mark done, start again from the top
     * 3. If the test has dependencies but none left to do: mark done, start again from the top
     * 4. When we reach the end add any leftover tests to the end. These will be marked 'skipped' during execution.
     *
     * @psalm-param array<DataProviderTestSuite|TestCase> $tests
     *
     * @psalm-return array<DataProviderTestSuite|TestCase>
     */
    private function resolveDependencies(array $tests) : array {
        $newTestOrder = [];
        $i = 0;
        $provided = [];
        do {
            if ([] === array_diff($tests[$i]->requires(), $provided)) {
                $provided = array_merge($provided, $tests[$i]->provides());
                $newTestOrder = array_merge($newTestOrder, array_splice($tests, $i, 1));
                $i = 0;
            }
            else {
                $i++;
            }
        } while (!empty($tests) && $i < count($tests));
        return array_merge($newTestOrder, $tests);
    }
    private function calculateTestExecutionOrder(Test $suite) : array {
        $tests = [];
        if ($suite instanceof TestSuite) {
            foreach ($suite->tests() as $test) {
                if (!$test instanceof TestSuite && $test instanceof Reorderable) {
                    $tests[] = $test->sortId();
                }
                else {
                    $tests = array_merge($tests, $this->calculateTestExecutionOrder($test));
                }
            }
        }
        return $tests;
    }

}