<?php

declare(strict_types=1);

// Flat-file storage primitives: atomic writes via a temp file plus rename, so
// a crashed request can never leave a half-written index behind.

function manageEnsureDirectory(string $dir): void
{
    if (!is_dir($dir) && !mkdir($dir, 02775, true) && !is_dir($dir)) {
        throw new RuntimeException("Verzeichnis konnte nicht erstellt werden: " . $dir);
    }

    @chmod($dir, 02775);
}

function manageReadJsonFile(string $file): array
{
    if (!is_file($file)) {
        return [];
    }

    $content = file_get_contents($file);
    if ($content === false || trim($content) === "") {
        return [];
    }

    $decoded = json_decode($content, true);
    if (!is_array($decoded)) {
        throw new RuntimeException("JSON-Datei ist beschädigt: " . basename($file));
    }

    return $decoded;
}

function manageWriteJsonFile(string $file, array $data): void
{
    manageEnsureDirectory(dirname($file));

    if (is_file($file) && !is_writable($file)) {
        @chmod($file, 0664);
    }

    $json = json_encode(
        $data,
        JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE,
    );
    if ($json === false) {
        throw new RuntimeException("JSON konnte nicht kodiert werden.");
    }

    $tmpFile = $file . ".tmp";
    if (file_put_contents($tmpFile, $json . PHP_EOL, LOCK_EX) === false) {
        throw new RuntimeException("JSON konnte nicht geschrieben werden.");
    }

    @chmod($tmpFile, 0664);

    // rename() is atomic on the same filesystem.
    if (!rename($tmpFile, $file)) {
        @unlink($tmpFile);
        throw new RuntimeException("JSON konnte nicht gespeichert werden.");
    }

    @chmod($file, 0664);
}

function manageRemoveDirectory(string $dir): void
{
    if (!is_dir($dir)) {
        return;
    }

    $items = new RecursiveIteratorIterator(
        new RecursiveDirectoryIterator($dir, FilesystemIterator::SKIP_DOTS),
        RecursiveIteratorIterator::CHILD_FIRST,
    );

    foreach ($items as $item) {
        if ($item->isDir()) {
            @rmdir($item->getPathname());
        } else {
            @unlink($item->getPathname());
        }
    }

    @rmdir($dir);
}

// Reads the first bytes of a file and reports whether they look like a ZIP
// local file / empty archive / spanned archive header.
function manageFileIsZip(string $path): bool
{
    $handle = @fopen($path, "rb");
    if ($handle === false) {
        return false;
    }

    $signature = fread($handle, 4);
    fclose($handle);

    return $signature === "PK\x03\x04" ||
        $signature === "PK\x05\x06" ||
        $signature === "PK\x07\x08";
}