<?php

declare(strict_types=1);

namespace Spiral\RoadRunner\Http;

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestFactoryInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Message\StreamFactoryInterface;
use Psr\Http\Message\StreamInterface;
use Psr\Http\Message\UploadedFileFactoryInterface;
use Psr\Http\Message\UploadedFileInterface;
use Spiral\RoadRunner\WorkerInterface;

/**
 * Manages PSR-7 request and response.
 *
 * @psalm-import-type UploadedFile from Request
 * @psalm-import-type UploadedFilesList from Request
 *
 * @api
 */
class PSR7Worker implements PSR7WorkerInterface
{
    /**
     * @var int Preferred chunk size for streaming output.
     *      if not greater than 0, then streaming response is turned off
     * @internal
     */
    public int $chunkSize = 0;

    private readonly HttpWorker $httpWorker;

    /**
     * @var string[] Valid values for HTTP protocol version
     */
    private static array $allowedVersions = ['1.0', '1.1', '2'];

    public function __construct(
        WorkerInterface $worker,
        private readonly ServerRequestFactoryInterface $requestFactory,
        private readonly StreamFactoryInterface $streamFactory,
        private readonly UploadedFileFactoryInterface $uploadsFactory,
    ) {
        $this->httpWorker = new HttpWorker($worker);
    }

    public function getWorker(): WorkerInterface
    {
        return $this->httpWorker->getWorker();
    }

    public function getHttpWorker(): HttpWorker
    {
        return $this->httpWorker;
    }

    /**
     * @psalm-suppress DeprecatedMethod
     *
     * @param bool $populateServer Whether to populate $_SERVER superglobal.
     *
     * @throws \JsonException
     */
    public function waitRequest(bool $populateServer = true): ?ServerRequestInterface
    {
        $httpRequest = $this->httpWorker->waitRequest();
        if ($httpRequest === null) {
            return null;
        }

        $vars = $this->configureServer($httpRequest);

        if ($populateServer) {
            $_SERVER = $vars;
        }

        return $this->mapRequest($httpRequest, $vars);
    }

    /**
     * Send response to the application server.
     *
     * @throws \JsonException
     */
    public function respond(ResponseInterface $response): void
    {
        $this->httpWorker->respond(
            $response->getStatusCode(),
            $this->chunkSize > 0
                ? $this->streamToGenerator($response->getBody())
                : (string) $response->getBody(),
            $response->getHeaders(),
        );
    }

    /**
     * Returns altered copy of _SERVER variable. Sets ip-address,
     * request-time and other values.
     *
     * @return non-empty-array<array-key|string, mixed|string>
     */
    protected function configureServer(Request $request): array
    {
        return GlobalState::enrichServerVars($request);
    }

    /**
     * @deprecated
     */
    protected function timeInt(): int
    {
        return \time();
    }

    /**
     * @deprecated
     */
    protected function timeFloat(): float
    {
        return \microtime(true);
    }

    /**
     * @throws \JsonException
     */
    protected function mapRequest(Request $httpRequest, array $server): ServerRequestInterface
    {
        $request = $this->requestFactory->createServerRequest(
            $httpRequest->method,
            $httpRequest->uri,
            $server,
        );

        $request = $request
            ->withProtocolVersion(static::fetchProtocolVersion($httpRequest->protocol))
            ->withCookieParams($httpRequest->cookies)
            ->withQueryParams($httpRequest->query)
            ->withUploadedFiles($this->wrapUploads($httpRequest->uploads))
        ;

        /** @psalm-suppress MixedAssignment */
        foreach ($httpRequest->attributes as $name => $value) {
            $request = $request->withAttribute($name, $value);
        }

        foreach ($httpRequest->headers as $name => $value) {
            $request = $request->withHeader($name, $value);
        }

        if ($httpRequest->parsed) {
            $request = $request->withParsedBody($httpRequest->getParsedBody());
        }

        if ($httpRequest->body !== '') {
            return $request->withBody($this->streamFactory->createStream($httpRequest->body));
        }

        return $request;
    }

    /**
     * Wraps all uploaded files with UploadedFile.
     *
     * @param UploadedFilesList $files
     * @return UploadedFileInterface[]|mixed[]
     */
    protected function wrapUploads(array $files): array
    {
        $result = [];

        foreach ($files as $index => $file) {
            if (! isset($file['name'])) {
                /** @psalm-var UploadedFilesList $file */
                $result[$index] = $this->wrapUploads($file);
                continue;
            }

            if ($file['error'] === \UPLOAD_ERR_OK) {
                $stream = $this->streamFactory->createStreamFromFile($file['tmpName']);
            } else {
                $stream = $this->streamFactory->createStream();
            }

            $result[$index] = $this->uploadsFactory->createUploadedFile(
                $stream,
                $file['size'],
                $file['error'],
                $file['name'],
                $file['mime'],
            );
        }

        return $result;
    }

    /**
     * Normalize HTTP protocol version to valid values
     */
    private static function fetchProtocolVersion(string $version): string
    {
        $v = \substr($version, 5);

        if ($v === '2.0') {
            return '2';
        }

        // Fallback for values outside of valid protocol versions
        if (! \in_array($v, static::$allowedVersions, true)) {
            return '1.1';
        }

        return $v;
    }

    /**
     * @return \Generator<mixed, scalar|\Stringable, mixed, \Stringable|scalar|null> Compatible
     *         with {@see HttpWorker::respondStream}.
     */
    private function streamToGenerator(StreamInterface $stream): \Generator
    {
        $stream->rewind();
        $size = $stream->getSize();
        if ($size !== null && $size < $this->chunkSize) {
            return (string) $stream;
        }
        $sum = 0;
        while (!$stream->eof()) {
            if ($size === null) {
                $chunk = $stream->read($this->chunkSize);
            } else {
                $left = $size - $sum;
                $chunk = $stream->read(\min($this->chunkSize, $left));
                if ($left <= $this->chunkSize && \strlen($chunk) === $left) {
                    return $chunk;
                }
            }
            $sum += \strlen($chunk);
            yield $chunk;
        }
    }
}