<?php
declare(strict_types=1);

/**
 * CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
 * Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 *
 * Licensed under The MIT License
 * For full copyright and license information, please see the LICENSE.txt
 * Redistributions of files must retain the above copyright notice.
 *
 * @copyright     Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
 * @link          https://cakephp.org CakePHP(tm) Project
 * @since         3.3.5
 * @license       https://opensource.org/licenses/mit-license.php MIT License
 *
 * Parts of this file are derived from Zend-Diactoros
 * @copyright Copyright (c) 2015-2016 Zend Technologies USA Inc. (https://www.zend.com/)
 * @license   https://github.com/zendframework/zend-diactoros/blob/master/LICENSE.md New BSD License
 */
namespace Cake\Http;

use Cake\Http\Cookie\Cookie;
use Cake\Http\Cookie\CookieInterface;
use Laminas\Diactoros\RelativeStream;
use Psr\Http\Message\ResponseInterface;

/**
 * Emits a Response to the PHP Server API.
 */
class ResponseEmitter
{
    /**
     * Maximum output buffering size for each iteration.
     *
     * @var int
     */
    protected int $maxBufferLength;

    /**
     * Constructor
     *
     * @param int $maxBufferLength Maximum output buffering size for each iteration.
     */
    public function __construct(int $maxBufferLength = 8192)
    {
        $this->maxBufferLength = $maxBufferLength;
    }

    /**
     * Emit a response.
     *
     * Emits a response, including status line, headers, and the message body,
     * according to the environment.
     *
     * @param \Psr\Http\Message\ResponseInterface $response The response to emit.
     * @return bool
     */
    public function emit(ResponseInterface $response): bool
    {
        $file = '';
        $line = 0;
        if (headers_sent($file, $line)) {
            $message = "Unable to emit headers. Headers sent in file={$file} line={$line}";
            trigger_error($message, E_USER_WARNING);
        }

        $this->emitStatusLine($response);
        $this->emitHeaders($response);
        $this->flush();

        $range = $this->parseContentRange($response->getHeaderLine('Content-Range'));
        if (is_array($range)) {
            $this->emitBodyRange($range, $response);
        } else {
            $this->emitBody($response);
        }

        if (function_exists('fastcgi_finish_request')) {
            fastcgi_finish_request();
        }

        return true;
    }

    /**
     * Emit the message body.
     *
     * @param \Psr\Http\Message\ResponseInterface $response The response to emit
     * @return void
     */
    protected function emitBody(ResponseInterface $response): void
    {
        if (in_array($response->getStatusCode(), [204, 304], true)) {
            return;
        }
        $body = $response->getBody();

        if (!$body->isSeekable()) {
            echo $body;

            return;
        }

        $body->rewind();
        while (!$body->eof()) {
            echo $body->read($this->maxBufferLength);
        }
    }

    /**
     * Emit a range of the message body.
     *
     * @param array $range The range data to emit
     * @param \Psr\Http\Message\ResponseInterface $response The response to emit
     * @return void
     */
    protected function emitBodyRange(array $range, ResponseInterface $response): void
    {
        [, $first, $last] = $range;

        $body = $response->getBody();

        if (!$body->isSeekable()) {
            $contents = $body->getContents();
            echo substr($contents, $first, $last - $first + 1);

            return;
        }

        $body = new RelativeStream($body, $first);
        $body->rewind();
        $pos = 0;
        /** @var int $length */
        $length = $last - $first + 1;
        while (!$body->eof() && $pos < $length) {
            if ($pos + $this->maxBufferLength > $length) {
                echo $body->read($length - $pos);
                break;
            }

            echo $body->read($this->maxBufferLength);
            $pos = $body->tell();
        }
    }

    /**
     * Emit the status line.
     *
     * Emits the status line using the protocol version and status code from
     * the response; if a reason phrase is available, it, too, is emitted.
     *
     * @param \Psr\Http\Message\ResponseInterface $response The response to emit
     * @return void
     */
    protected function emitStatusLine(ResponseInterface $response): void
    {
        $reasonPhrase = $response->getReasonPhrase();
        header(sprintf(
            'HTTP/%s %d%s',
            $response->getProtocolVersion(),
            $response->getStatusCode(),
            ($reasonPhrase ? ' ' . $reasonPhrase : ''),
        ));
    }

    /**
     * Emit response headers.
     *
     * Loops through each header, emitting each; if the header value
     * is an array with multiple values, ensures that each is sent
     * in such a way as to create aggregate headers (instead of replace
     * the previous).
     *
     * @param \Psr\Http\Message\ResponseInterface $response The response to emit
     * @return void
     */
    protected function emitHeaders(ResponseInterface $response): void
    {
        $cookies = [];
        if ($response instanceof Response) {
            $cookies = iterator_to_array($response->getCookieCollection());
        }

        foreach ($response->getHeaders() as $name => $values) {
            if (strtolower($name) === 'set-cookie') {
                $cookies = array_merge($cookies, $values);
                continue;
            }
            $first = true;
            foreach ($values as $value) {
                header(sprintf(
                    '%s: %s',
                    $name,
                    $value,
                ), $first);
                $first = false;
            }
        }

        $this->emitCookies($cookies);
    }

    /**
     * Emit cookies using setcookie()
     *
     * @param array<\Cake\Http\Cookie\CookieInterface|string> $cookies An array of cookies.
     * @return void
     */
    protected function emitCookies(array $cookies): void
    {
        foreach ($cookies as $cookie) {
            $this->setCookie($cookie);
        }
    }

    /**
     * Helper methods to set cookie.
     *
     * @param \Cake\Http\Cookie\CookieInterface|string $cookie Cookie.
     * @return bool
     */
    protected function setCookie(CookieInterface|string $cookie): bool
    {
        if (is_string($cookie)) {
            $cookie = Cookie::createFromHeaderString($cookie, ['path' => '']);
        }

        return setcookie($cookie->getName(), $cookie->getScalarValue(), $cookie->getOptions());
    }

    /**
     * Loops through the output buffer, flushing each, before emitting
     * the response.
     *
     * @param int|null $maxBufferLevel Flush up to this buffer level.
     * @return void
     */
    protected function flush(?int $maxBufferLevel = null): void
    {
        $maxBufferLevel ??= ob_get_level();

        while (ob_get_level() > $maxBufferLevel) {
            ob_end_flush();
        }
    }

    /**
     * Parse content-range header
     * https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.16
     *
     * @param string $header The Content-Range header to parse.
     * @return array|false [unit, first, last, length]; returns false if no
     *     content range or an invalid content range is provided
     */
    protected function parseContentRange(string $header): array|false
    {
        if (preg_match('/(?P<unit>[\w]+)\s+(?P<first>\d+)-(?P<last>\d+)\/(?P<length>\d+|\*)/', $header, $matches)) {
            return [
                $matches['unit'],
                (int)$matches['first'],
                (int)$matches['last'],
                $matches['length'] === '*' ? '*' : (int)$matches['length'],
            ];
        }

        return false;
    }
}
