<?php

declare(strict_types=1);

namespace App\Controller;

use App\Agent\AgentRunner;
use App\Http\ClientIdResolver;
use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\StreamedResponse;
use Symfony\Component\Routing\Annotation\Route;

final readonly class AskSseController
{
    private const JOB_TTL_SECONDS = 900;

    public function __construct(
        private AgentRunner $agentRunner,
        private ClientIdResolver $clientIdResolver,
        private string $projectDir,
    ) {
    }

    #[Route('/ask-jobs', name: 'ask_job_start', methods: ['POST'])]
    public function startJob(Request $request): JsonResponse
    {
        $data = json_decode($request->getContent(), true);
        $prompt = trim((string) ($data['prompt'] ?? ''));

        if ($prompt === '') {
            return new JsonResponse(['error' => 'Empty prompt'], Response::HTTP_BAD_REQUEST);
        }

        /**
         * Default:
         * - Browser chat uses budgeted recent context
         * - Full context must be explicitly requested
         */
        $includeFullContext = filter_var(
            $data['fullContext'] ?? false,
            FILTER_VALIDATE_BOOL
        );

        $cookieResponse = new Response();
        $clientId = $this->clientIdResolver->resolve($request, $cookieResponse);

        try {
            $this->cleanupExpiredJobs();
            $jobId = bin2hex(random_bytes(24));
            $this->writeJob($jobId, [
                'prompt' => $prompt,
                'clientId' => $clientId,
                'includeFullContext' => $includeFullContext,
                'createdAt' => time(),
            ]);
        } catch (\Throwable $e) {
            return new JsonResponse(
                ['error' => 'Stream job could not be created: ' . $this->formatThrowableForClient($e)],
                Response::HTTP_INTERNAL_SERVER_ERROR
            );
        }

        $response = new JsonResponse(['jobId' => $jobId]);

        foreach ($cookieResponse->headers->getCookies() as $cookie) {
            $response->headers->setCookie($cookie);
        }

        return $response;
    }

    #[Route('/ask-sse/{jobId}', name: 'ask_sse_job', methods: ['GET'], requirements: ['jobId' => '[a-f0-9]{48}'])]
    public function streamJob(string $jobId): StreamedResponse
    {
        return new StreamedResponse(
            function () use ($jobId): void {
                $job = $this->readJob($jobId);

                if ($job === null) {
                    $this->prepareStreamRuntime();
                    echo "retry: 15000\n\n";
                    $this->sendEvent('error', 'Der Antwort-Job ist abgelaufen oder wurde nicht gefunden. Bitte sende die Anfrage erneut.');
                    $this->sendEvent('done', '[DONE]');
                    return;
                }

                $this->deleteJob($jobId);
                $this->streamAgentResponse(
                    prompt: (string) ($job['prompt'] ?? ''),
                    clientId: (string) ($job['clientId'] ?? ''),
                    includeFullContext: (bool) ($job['includeFullContext'] ?? false),
                    cookieResponse: null
                );
            },
            Response::HTTP_OK,
            $this->streamHeaders()
        );
    }

    #[Route('/ask-sse', name: 'ask_sse', methods: ['POST'])]
    public function stream(Request $request): StreamedResponse
    {
        $data = json_decode($request->getContent(), true);
        $prompt = trim((string) ($data['prompt'] ?? ''));

        /**
         * Default:
         * - Browser chat uses budgeted recent context
         * - Full context must be explicitly requested
         */
        $includeFullContext = filter_var(
            $data['fullContext'] ?? false,
            FILTER_VALIDATE_BOOL
        );

        $cookieResponse = new Response();
        $clientId = $this->clientIdResolver->resolve($request, $cookieResponse);

        return new StreamedResponse(
            function () use ($prompt, $clientId, $cookieResponse, $includeFullContext): void {
                $this->streamAgentResponse(
                    prompt: $prompt,
                    clientId: $clientId,
                    includeFullContext: $includeFullContext,
                    cookieResponse: $cookieResponse
                );
            },
            Response::HTTP_OK,
            $this->streamHeaders()
        );
    }

    private function streamAgentResponse(
        string $prompt,
        string $clientId,
        bool $includeFullContext,
        ?Response $cookieResponse
    ): void {
        $this->prepareStreamRuntime();
        $this->registerStreamShutdownErrorHandler();

        if ($cookieResponse !== null) {
            foreach ($cookieResponse->headers->getCookies() as $cookie) {
                header('Set-Cookie: ' . $cookie, false);
            }
        }

        echo "retry: 15000\n\n";
        $this->sendComment('stream-open');

        if ($prompt === '') {
            $this->sendEvent('error', 'Empty prompt');
            $this->sendEvent('done', '[DONE]');
            return;
        }

        try {
            foreach ($this->agentRunner->run($prompt, $clientId, $includeFullContext) as $chunk) {
                if (connection_aborted() === 1) {
                    return;
                }

                $chunk = str_replace(["\r\n", "\r"], "\n", $chunk);
                $this->sendData($chunk);
            }
        } catch (\Throwable $e) {
            $this->sendEvent(
                'error',
                '❌ Stream abgebrochen: ' . $this->formatThrowableForClient($e)
            );
        }

        $this->sendEvent('done', '[DONE]');
    }

    private function registerStreamShutdownErrorHandler(): void
    {
        register_shutdown_function(function (): void {
            $error = error_get_last();

            if ($error === null) {
                return;
            }

            $fatalTypes = [E_ERROR, E_PARSE, E_CORE_ERROR, E_COMPILE_ERROR, E_USER_ERROR];

            if (!in_array((int) ($error['type'] ?? 0), $fatalTypes, true)) {
                return;
            }

            $message = sprintf(
                '❌ Fataler Serverfehler: %s in %s:%s',
                (string) ($error['message'] ?? 'unknown error'),
                (string) ($error['file'] ?? 'unknown file'),
                (string) ($error['line'] ?? '?')
            );

            $this->sendEvent('error', $message);
            $this->sendEvent('done', '[DONE]');
        });
    }

    private function formatThrowableForClient(\Throwable $e): string
    {
        $message = trim($e->getMessage());

        if ($message === '') {
            $message = $e::class;
        }

        return preg_replace('/\s+/u', ' ', $message) ?? $message;
    }

    private function prepareStreamRuntime(): void
    {
        @set_time_limit(0);
        @ini_set('output_buffering', 'off');
        @ini_set('zlib.output_compression', '0');

        while (ob_get_level() > 0) {
            ob_end_flush();
        }
    }

    /**
     * @return array<string, string>
     */
    private function streamHeaders(): array
    {
        return [
            'Content-Type' => 'text/event-stream; charset=utf-8',
            'Cache-Control' => 'no-cache, no-store, must-revalidate, no-transform',
            'Connection' => 'keep-alive',
            'X-Accel-Buffering' => 'no',
            'X-Content-Type-Options' => 'nosniff',
        ];
    }

    private function sendData(string $data): void
    {
        if ($data === '') {
            $this->sendComment('keepalive');
            return;
        }

        $lines = explode("\n", $data);

        foreach ($lines as $line) {
            echo 'data: ' . $line . "\n";
        }

        echo "\n";
        $this->flushOutput();
    }

    private function sendEvent(string $event, string $data): void
    {
        $safe = str_replace(["\r", "\n"], ' ', $data);

        echo "event: {$event}\n";
        echo "data: {$safe}\n\n";
        $this->flushOutput();
    }

    private function sendComment(string $comment): void
    {
        $safe = str_replace(["\r", "\n"], ' ', $comment);

        echo ': ' . $safe . "\n\n";
        $this->flushOutput();
    }

    private function flushOutput(): void
    {
        if (function_exists('ob_flush')) {
            @ob_flush();
        }

        @flush();
    }

    /**
     * @param array<string, mixed> $payload
     */
    private function writeJob(string $jobId, array $payload): void
    {
        $directory = $this->jobDirectory();

        if (!is_dir($directory) && !mkdir($directory, 0775, true) && !is_dir($directory)) {
            throw new \RuntimeException('Stream job directory could not be created.');
        }

        $json = json_encode($payload, JSON_THROW_ON_ERROR | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);

        if (file_put_contents($this->jobPath($jobId), $json, LOCK_EX) === false) {
            throw new \RuntimeException('Stream job could not be written.');
        }
    }

    /**
     * @return array<string, mixed>|null
     */
    private function readJob(string $jobId): ?array
    {
        if (!preg_match('/\A[a-f0-9]{48}\z/', $jobId)) {
            return null;
        }

        $path = $this->jobPath($jobId);

        if (!is_file($path)) {
            return null;
        }

        $content = file_get_contents($path);

        if (!is_string($content) || $content === '') {
            return null;
        }

        $data = json_decode($content, true);

        if (!is_array($data)) {
            return null;
        }

        $createdAt = (int) ($data['createdAt'] ?? 0);

        if ($createdAt <= 0 || time() - $createdAt > self::JOB_TTL_SECONDS) {
            $this->deleteJob($jobId);
            return null;
        }

        return $data;
    }

    private function deleteJob(string $jobId): void
    {
        $path = $this->jobPath($jobId);

        if (is_file($path)) {
            @unlink($path);
        }
    }

    private function cleanupExpiredJobs(): void
    {
        $directory = $this->jobDirectory();

        if (!is_dir($directory)) {
            return;
        }

        $threshold = time() - self::JOB_TTL_SECONDS;

        foreach (glob($directory . '/*.json') ?: [] as $path) {
            if (!is_file($path)) {
                continue;
            }

            $mtime = filemtime($path);

            if ($mtime === false || $mtime < $threshold) {
                @unlink($path);
            }
        }
    }

    private function jobPath(string $jobId): string
    {
        return $this->jobDirectory() . '/' . $jobId . '.json';
    }

    private function jobDirectory(): string
    {
        return rtrim($this->projectDir, '/\\') . '/var/stream_jobs';
    }
}