<?php

declare(strict_types=1);

namespace BlaxSoftware\LaravelWebSockets\Test\Websocket;

use BlaxSoftware\LaravelWebSockets\Ipc\SocketPairIpc;
use BlaxSoftware\LaravelWebSockets\Server\ChildProcesses;
use BlaxSoftware\LaravelWebSockets\Test\Mocks;
use BlaxSoftware\LaravelWebSockets\Test\TestCase;
use BlaxSoftware\LaravelWebSockets\Websocket\ChildMessageOutcome;
use BlaxSoftware\LaravelWebSockets\Websocket\ControllerResolver;
use BlaxSoftware\LaravelWebSockets\Websocket\EventRegistry;
use BlaxSoftware\LaravelWebSockets\Websocket\Handler;

/**
 * End to end through Handler::forkWithSocketPair(), with real message
 * children (#2465, #1462):
 *  - the child closes its copy of the server's listening socket,
 *  - the shutdown stops a child that is still running,
 *  - a child that dies without replying is answered by the parent,
 *  - a child that replied gets no extra frame.
 */
class HandlerChildLifecycleTest extends TestCase
{
    private const FIXTURES_NS = 'BlaxSoftware\\LaravelWebSockets\\Test\\Websocket\\Fixtures\\ChildCrash';

    public function setUp(): void
    {
        parent::setUp();

        if (! SocketPairIpc::isSupported() || ! function_exists('pcntl_fork') || ! function_exists('posix_kill')) {
            $this->markTestSkipped('pcntl, posix and sockets are required');
        }

        if (! class_exists(\Illuminate\Support\Defer\DeferredCallbackCollection::class)) {
            require_once __DIR__ . '/Fixtures/DeferredCallbackCollectionStub.php';
        }

        ChildProcesses::flush();
        ControllerResolver::clearCache();
        EventRegistry::clear();
        EventRegistry::setSearchPaths([
            __DIR__ . '/Fixtures/ChildCrash' => self::FIXTURES_NS,
        ]);
    }

    public function tearDown(): void
    {
        // Never leave a forked child behind, even after a failed assertion.
        ChildProcesses::terminateAll(0.0, 1.0);
        ChildProcesses::flush();

        EventRegistry::clear();
        (new \ReflectionProperty(EventRegistry::class, 'searchPaths'))->setValue(null, null);

        parent::tearDown();
    }

    public function test_a_child_killed_before_replying_is_answered_by_the_parent()
    {
        $connection = $this->send('child-crash.killed');

        $this->runLoopUntil(fn () => $this->sentEvent($connection, 'child-crash.killed:error') !== null);

        $error = $this->sentEvent($connection, 'child-crash.killed:error');
        $this->assertNotNull($error, 'The client must not wait forever for a child that died.');
        $this->assertSame('Internal server error', $error['data']['message']);
        $this->assertFalse($error['data']['meta']['reported']);
        $this->assertSame(0, ChildProcesses::count(), 'The dead child was reaped and forgotten.');
    }

    public function test_a_child_that_replied_gets_no_extra_error_frame()
    {
        $connection = $this->send('child-crash.ok');

        $this->runLoopUntil(
            fn () => ChildProcesses::count() === 0 && $this->sentEvent($connection, 'child-crash.ok:response') !== null,
            5.0,
            0.2
        );

        $response = $this->sentEvent($connection, 'child-crash.ok:response');
        $this->assertNotNull($response);
        $this->assertSame(['ok' => true], $response['data']);
        $connection->assertNotSentEvent('child-crash.ok:error');
    }

    public function test_a_running_child_neither_holds_the_port_nor_survives_the_shutdown()
    {
        $server = stream_socket_server('tcp://127.0.0.1:0', $errno, $errstr);
        $this->assertIsResource($server, $errstr);
        $port = (int) parse_url('tcp://' . stream_socket_get_name($server, false), PHP_URL_PORT);
        $this->assertTrue(ChildProcesses::registerListener($server));

        $connection = $this->send('child-crash.hold');
        $this->assertSame(1, ChildProcesses::count());
        [$pid] = ChildProcesses::pids();

        // The server closes its socket while the child is still busy: the port
        // frees as soon as the child has dropped its inherited copy.
        fclose($server);
        $successor = false;
        $deadline = microtime(true) + 5;
        while ($successor === false && microtime(true) < $deadline) {
            $successor = @stream_socket_server("tcp://127.0.0.1:{$port}", $errno, $errstr);
            if ($successor === false) {
                usleep(20_000);
            }
        }
        $this->assertIsResource($successor, "The busy child kept port {$port} bound: {$errstr}");
        fclose($successor);
        $this->assertTrue(posix_kill($pid, 0), 'The child is still running its handler.');

        // Server shutdown: SIGTERM does end the child (default disposition
        // restored after fork), no SIGKILL needed.
        $stats = ChildProcesses::terminateAll(2.0);
        $this->assertSame(['terminated' => 1, 'killed' => 0, 'remaining' => 0], $stats);
        $this->assertFalse(@posix_kill($pid, 0));

        // Its client is told instead of waiting for a reply that never comes.
        $this->runLoopUntil(fn () => $this->sentEvent($connection, 'child-crash.hold:error') !== null);
        $error = $this->sentEvent($connection, 'child-crash.hold:error');
        $this->assertNotNull($error);
        $this->assertSame('Server is restarting', $error['data']['message']);
    }

    public function test_the_fatal_error_frame_is_recognised_as_the_reply()
    {
        $method = new \ReflectionMethod(Handler::class, 'fatalErrorFrame');
        if (PHP_VERSION_ID < 80100) {
            $method->setAccessible(true);
        }

        $message = ['event' => 'child-crash.ok[u1]', 'data' => [], 'channel' => 'crash-channel'];
        $frame = $method->invoke(null, $message, 'crash-channel');

        // Same shape as the controller's catch-all error frame.
        $this->assertSame([
            'event' => 'child-crash.ok[u1]:error',
            'data' => ['message' => 'Internal server error', 'meta' => ['reported' => true, 'fatal' => true]],
            'channel' => 'crash-channel',
        ], json_decode($frame, true));

        // The parent must count it as the reply, or it would add its own
        // error frame on top of it.
        $outcome = new ChildMessageOutcome($message['event'], fn () => null);
        $outcome->frameReceived($frame);

        $this->assertTrue($outcome->replied());
    }

    private function send(string $event): Mocks\Connection
    {
        $connection = $this->newActiveConnection(['crash-channel']);
        $connection->resetEvents();

        $this->wsHandler->onMessage($connection, new Mocks\Message([
            'event' => $event,
            'data' => [],
            'channel' => 'crash-channel',
        ]));

        return $connection;
    }

    /**
     * Run the loop with StartServer's reaper until $done or the timeout, then
     * keep it running for $settle seconds.
     */
    private function runLoopUntil(callable $done, float $timeout = 5.0, float $settle = 0.0): void
    {
        $finishedAt = null;

        $tick = $this->loop->addPeriodicTimer(0.02, function () use ($done, $settle, &$finishedAt) {
            ChildProcesses::reapExited();

            if ($finishedAt === null && $done()) {
                $finishedAt = microtime(true);
            }

            if ($finishedAt !== null && microtime(true) - $finishedAt >= $settle) {
                $this->loop->stop();
            }
        });
        $timeoutTimer = $this->loop->addTimer($timeout, fn () => $this->loop->stop());

        $this->loop->run();

        $this->loop->cancelTimer($tick);
        $this->loop->cancelTimer($timeoutTimer);
    }

    private function sentEvent(Mocks\Connection $connection, string $event): ?array
    {
        foreach ($connection->sentData as $frame) {
            if (($frame['event'] ?? null) === $event) {
                return $frame;
            }
        }

        return null;
    }
}