<?php
/*
 * Shared handling for the Racket installation zip and its binary parts.
 */

define('RACKET_ZIP_FILE', dirname(__DIR__) . '/config/racket.zip');
define('RACKET_ZIP_DATA_DIR', dirname(__DIR__) . '/data');
define('RACKET_ZIP_PART_PREFIX', 'racket-part-');
define('RACKET_ZIP_MANIFEST_FILE', RACKET_ZIP_DATA_DIR . '/racket-parts.json');

function racket_zip_binary_chunk_bytes_for_base64_kib($kib)
{
    return intdiv(((int)$kib) * 1024, 4) * 3;
}

function racket_zip_part_name($nr)
{
    return RACKET_ZIP_PART_PREFIX . sprintf('%06d', $nr);
}

function racket_zip_part_file($partNumber)
{
    return RACKET_ZIP_DATA_DIR . '/' . RACKET_ZIP_PART_PREFIX . $partNumber;
}

function racket_zip_ensure_data_dir()
{
    if (!is_dir(RACKET_ZIP_DATA_DIR)) {
        if (!mkdir(RACKET_ZIP_DATA_DIR, 0755, true)) {
            throw new RuntimeException('Kan data directory niet maken: ' . RACKET_ZIP_DATA_DIR);
        }
    }

    if (!is_writable(RACKET_ZIP_DATA_DIR)) {
        throw new RuntimeException('Data directory is niet schrijfbaar: ' . RACKET_ZIP_DATA_DIR);
    }
}

function racket_zip_remove_old_parts()
{
    foreach (glob(RACKET_ZIP_DATA_DIR . '/' . RACKET_ZIP_PART_PREFIX . '*') ?: array() as $file) {
        if (is_file($file)) {
            @unlink($file);
        }
    }

    if (is_file(RACKET_ZIP_MANIFEST_FILE)) {
        @unlink(RACKET_ZIP_MANIFEST_FILE);
    }
}

function split_racket_zip_parts($maxBase64Kib)
{
    $maxBase64Bytes = (int)$maxBase64Kib * 1024;
    $binaryChunkBytes = racket_zip_binary_chunk_bytes_for_base64_kib($maxBase64Kib);

    if ($binaryChunkBytes < 3) {
        throw new RuntimeException('Ongeldige racket.zip base64 chunk-instelling.');
    }

    if (!is_file(RACKET_ZIP_FILE) || !is_readable(RACKET_ZIP_FILE)) {
        throw new RuntimeException('racket.zip ontbreekt of is niet leesbaar: ' . RACKET_ZIP_FILE);
    }

    racket_zip_ensure_data_dir();
    racket_zip_remove_old_parts();

    $in = fopen(RACKET_ZIP_FILE, 'rb');

    if ($in === false) {
        throw new RuntimeException('Kan racket.zip niet openen.');
    }

    $parts = array();
    $nr = 1;
    $totalBinaryBytes = 0;

    while (!feof($in)) {
        $buf = fread($in, $binaryChunkBytes);

        if ($buf === false) {
            fclose($in);
            throw new RuntimeException('Fout bij lezen van racket.zip.');
        }

        if ($buf === '') {
            break;
        }

        $name = racket_zip_part_name($nr);
        $file = RACKET_ZIP_DATA_DIR . '/' . $name;

        if (file_put_contents($file, $buf, LOCK_EX) === false) {
            fclose($in);
            throw new RuntimeException('Kan part niet schrijven: ' . $file);
        }

        $n = sprintf('%06d', $nr);
        $binaryBytes = strlen($buf);

        $parts[] = array(
            'number' => $n,
            'name' => $name,
            'file' => $file,
            'size' => $binaryBytes,
        );

        $totalBinaryBytes += $binaryBytes;
        $nr++;
    }

    fclose($in);

    if (count($parts) === 0) {
        throw new RuntimeException('racket.zip lijkt leeg te zijn.');
    }

    $manifest = array(
        'source_file' => RACKET_ZIP_FILE,
        'source_bytes' => filesize(RACKET_ZIP_FILE),
        'source_mtime' => filemtime(RACKET_ZIP_FILE),
        'source_sha256' => hash_file('sha256', RACKET_ZIP_FILE),
        'max_base64_kib' => (int)$maxBase64Kib,
        'max_base64_bytes' => $maxBase64Bytes,
        'binary_chunk_bytes' => $binaryChunkBytes,
        'part_count' => count($parts),
        'total_binary_bytes' => $totalBinaryBytes,
        'parts' => $parts,
        'created_at' => gmdate('c'),
    );

    if (file_put_contents(
        RACKET_ZIP_MANIFEST_FILE,
        json_encode($manifest, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES) . "\n",
        LOCK_EX
    ) === false) {
        throw new RuntimeException('Kan racket.zip manifest niet schrijven: ' . RACKET_ZIP_MANIFEST_FILE);
    }

    return $manifest;
}

function load_racket_zip_parts_manifest()
{
    if (!is_file(RACKET_ZIP_MANIFEST_FILE) || !is_readable(RACKET_ZIP_MANIFEST_FILE)) {
        throw new RuntimeException('racket.zip parts-manifest ontbreekt: ' . RACKET_ZIP_MANIFEST_FILE);
    }

    $raw = file_get_contents(RACKET_ZIP_MANIFEST_FILE);

    if ($raw === false) {
        throw new RuntimeException('Kan racket.zip parts-manifest niet lezen: ' . RACKET_ZIP_MANIFEST_FILE);
    }

    $manifest = json_decode($raw, true);

    if (!is_array($manifest)) {
        throw new RuntimeException('racket.zip parts-manifest is geen geldige JSON: ' . RACKET_ZIP_MANIFEST_FILE);
    }

    return $manifest;
}

function racket_zip_parts_current($manifest, $maxBase64Kib)
{
    if (!is_array($manifest)) {
        return false;
    }

    if ((int)($manifest['max_base64_kib'] ?? 0) !== (int)$maxBase64Kib) {
        return false;
    }

    if (!is_file(RACKET_ZIP_FILE)) {
        return false;
    }

    if ((int)($manifest['source_bytes'] ?? -1) !== (int)filesize(RACKET_ZIP_FILE)) {
        return false;
    }

    if ((int)($manifest['source_mtime'] ?? -1) !== (int)filemtime(RACKET_ZIP_FILE)) {
        return false;
    }

    foreach (($manifest['parts'] ?? array()) as $part) {
        $number = (string)($part['number'] ?? '');
        $file = racket_zip_part_file($number);

        if (!preg_match('/^[0-9]{6}$/', $number) || !is_file($file) || !is_readable($file)) {
            return false;
        }
    }

    return count($manifest['parts'] ?? array()) > 0;
}