<?php

declare(strict_types=1);

namespace Demostf\API\Demo;

use InvalidArgumentException;

class HeaderParser {
    /**
     * @param string $head string containing the demo header binary data
     *
     * @throws InvalidArgumentException
     */
    public function parseString(string $head): Header {
        $info = @unpack(
            'A8type/Iversion/Iprotocol/A260server/A260nick/A260map/A260game/fduration/Vticks/Vframes/Vsigon',
            $head
        );
        if (!isset($info['type']) || 'HL2DEMO' !== $info['type']) {
            throw new InvalidArgumentException('Not an HL2 demo');
        }

        return Header::fromArray($info);
    }

    /**
     * Parse demo info from a stream.
     *
     * @param resource $stream
     *
     * @throws InvalidArgumentException
     */
    public function parseStream($stream): Header {
        $head = fread($stream, 2048);

        return $this->parseString($head);
    }

    /**
     * Parse demo info from a local file.
     *
     * @throws InvalidArgumentException
     */
    public function parseHeader(string $path): Header {
        if (!is_readable($path)) {
            throw new InvalidArgumentException('Unable to open demo: ' . $path);
        }
        $fh = fopen($path, 'r');

        return $this->parseStream($fh);
    }
}