<?php

/*
 * This file is part of the official PHP MCP SDK.
 *
 * A collaboration between Symfony and the PHP Foundation.
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Matomo\Dependencies\McpServer\Mcp\Server\Transport;

use Matomo\Dependencies\McpServer\Mcp\Exception\RuntimeException;
use Matomo\Dependencies\McpServer\Psr\Http\Message\StreamInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
/**
 * A PSR-7 StreamInterface that executes a callback when read.
 *
 * This enables true streaming with echo/flush() for SSE (Server-Sent Events).
 * The callback is executed once when the stream is first read and can write
 * directly to the output buffer (e.g. via echo + flush()).
 *
 * Example usage for SSE:
 * ```php
 * $stream = new CallbackStream(function() {
 *     echo "event: message\n";
 *     echo "data: {\"hello\":\"world\"}\n\n";
 *     flush();
 * });
 * ```
 *
 * @author Kyrian Obikwelu <koshnawaza@gmail.com>
 */
final class CallbackStream implements \Stringable, StreamInterface
{
    private bool $called = \false;
    private ?\Throwable $exception = null;
    /**
     * @param callable(): void $callback The callback to execute when stream is read
     */
    public function __construct(private $callback, private LoggerInterface $logger = new NullLogger())
    {
    }
    public function __toString() : string
    {
        try {
            $this->invoke();
        } catch (\Throwable $e) {
            $this->exception = $e;
            $this->logger->error(\sprintf('CallbackStream execution failed: %s', $e->getMessage()), ['exception' => $e]);
        }
        return '';
    }
    public function read($length) : string
    {
        $this->invoke();
        if (null !== $this->exception) {
            throw $this->exception;
        }
        return '';
    }
    public function getContents() : string
    {
        $this->invoke();
        if (null !== $this->exception) {
            throw $this->exception;
        }
        return '';
    }
    public function eof() : bool
    {
        return $this->called;
    }
    public function close() : void
    {
        // No-op - callback-based stream doesn't need closing
    }
    public function detach()
    {
        return null;
    }
    public function getSize() : ?int
    {
        return null;
        // Unknown size for callback streams
    }
    public function tell() : int
    {
        return 0;
    }
    public function isSeekable() : bool
    {
        return \false;
    }
    public function seek($offset, $whence = \SEEK_SET) : void
    {
        throw new RuntimeException('Stream is not seekable');
    }
    public function rewind() : void
    {
        throw new RuntimeException('Stream is not rewindable');
    }
    public function isWritable() : bool
    {
        return \false;
    }
    public function write($string) : int
    {
        throw new RuntimeException('Stream is not writable');
    }
    public function isReadable() : bool
    {
        return !$this->called;
    }
    private function invoke() : void
    {
        if ($this->called) {
            return;
        }
        $this->called = \true;
        $this->exception = null;
        ($this->callback)();
    }
    public function getMetadata($key = null)
    {
        return null === $key ? [] : null;
    }
}
