<?php

namespace App\Services;

use Illuminate\Support\Facades\Process;
use RuntimeException;

/**
 * Repair Coruna obfuscated 7z headers and extract with p7zip.
 */
class CorunaArchive
{
    private const STANDARD_PREFIX = "7z\xBC\xAF'\x1C";

    private const HEADER_XOR = 0x1234567800ABCDEF;

    private const HEADER_MARKER_1 = 0x000A000900010804;

    private const HEADER_MARKER_2 = 0x009812000B0F0D0C;

    public function __construct(
        private readonly CorunaCrypto $crypto,
        private readonly string $sevenZip = '/opt/homebrew/opt/p7zip/bin/7z',
    ) {}

    public function isCorunaHeader(string $data): bool
    {
        if (strlen($data) < 32) {
            return false;
        }
        if (str_starts_with($data, self::STANDARD_PREFIX)) {
            return false;
        }
        $m1 = unpack('P', substr($data, 16, 8))[1];
        $m2 = unpack('P', substr($data, 24, 8))[1];

        return $m1 === self::HEADER_MARKER_1 && $m2 === self::HEADER_MARKER_2;
    }

    public function repairHeader(string $data): string
    {
        if (str_starts_with($data, self::STANDARD_PREFIX)) {
            return $data;
        }
        if (strlen($data) < 33 || ! $this->isCorunaHeader($data)) {
            throw new RuntimeException('not a Coruna header-obfuscated 7z archive');
        }

        $nextHeaderOffset = unpack('P', substr($data, 0, 8))[1] ^ self::HEADER_XOR;
        $nextHeaderSize = unpack('P', substr($data, 8, 8))[1] ^ self::HEADER_XOR;
        $nextHeaderStart = 32 + $nextHeaderOffset;
        $nextHeaderEnd = $nextHeaderStart + $nextHeaderSize;
        if ($nextHeaderSize === 0 || $nextHeaderEnd > strlen($data)) {
            throw new RuntimeException('invalid Coruna 7z bounds');
        }

        $repaired = $data;
        $repaired = substr_replace($repaired, self::STANDARD_PREFIX."\x00\x04", 0, 8);
        $repaired = substr_replace($repaired, pack('P', $nextHeaderOffset), 12, 8);
        $repaired = substr_replace($repaired, pack('P', $nextHeaderSize), 20, 8);
        $nextCrc = crc32(substr($repaired, $nextHeaderStart, $nextHeaderSize)) & 0xFFFFFFFF;
        $repaired = substr_replace($repaired, pack('V', $nextCrc), 28, 4);
        $startCrc = crc32(substr($repaired, 12, 20)) & 0xFFFFFFFF;
        $repaired = substr_replace($repaired, pack('V', $startCrc), 8, 4);

        return $repaired;
    }

    public function extract(string $wireData, string $destDir, string $batchBase = '0'): array
    {
        if (! is_dir($destDir)) {
            mkdir($destDir, 0755, true);
        }

        try {
            $repaired = $this->repairHeader($wireData);
        } catch (\Throwable $e) {
            $repaired = $wireData;
        }

        $archive = $destDir.'/capture.7z';
        file_put_contents($archive, $repaired);
        file_put_contents($destDir.'/wire.bin', $wireData);
        $password = $this->crypto->archivePassword($batchBase);
        $membersDir = $destDir.'/members';
        @mkdir($membersDir, 0755, true);

        $bin = is_executable($this->sevenZip) ? $this->sevenZip : '7z';
        $result = Process::timeout(120)->run([
            $bin, 'x', '-y',
            '-p'.$password,
            '-o'.$membersDir,
            $archive,
        ]);

        $files = [];
        if (is_dir($membersDir)) {
            $it = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator(
                $membersDir,
                \FilesystemIterator::SKIP_DOTS
            ));
            foreach ($it as $file) {
                if ($file->isFile()) {
                    $files[] = $file->getPathname();
                }
            }
        }

        return [
            'ok' => $result->successful() && count($files) > 0,
            'stderr' => $result->errorOutput(),
            'files' => $files,
            'password_recipe' => 'session_key||'.$batchBase,
        ];
    }
}