#!/usr/bin/env php
<?php declare(strict_types=1);
/**
 * PrivateBin
 *
 * a zero-knowledge paste bin
 *
 * @link      https://github.com/PrivateBin/PrivateBin
 * @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
 * @license   https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
 */

/**
 * Regenerates the subresource integrity (SRI) hashes of all JavaScript files
 * in the 'sri' array of lib/Configuration.php. Entries for new files get
 * added, entries for removed files get dropped and the array is kept sorted.
 * On master this is run by the GitHub workflow .github/workflows/sri.yml.
 */

define('PATH', dirname(__FILE__) . DIRECTORY_SEPARATOR . '..' . DIRECTORY_SEPARATOR);

// JS files that browsers never load, so they need no SRI hash
const IGNORED_FILES = ['common.js', 'eslint.config.js'];

$opts = getopt('ch', ['check', 'help']);
if ($opts === false) {
    fail('Erroneous command line options. Please use --help');
}
if (array_key_exists('h', $opts) || array_key_exists('help', $opts)) {
    echo <<<'EOT'
Usage:
  sri [--check]

Regenerates the SRI hashes of all JavaScript files in js/ and writes them into
the 'sri' array of lib/Configuration.php.

Options:
  -c, --check   don't write anything, exit with status 1 if any hash is
                outdated, missing or superfluous
  -h, --help    displays this help message

EOT;
    exit(0);
}
$check = array_key_exists('c', $opts) || array_key_exists('check', $opts);

// calculate the hashes of all JS files
$hashes = [];
foreach (glob(PATH . 'js' . DIRECTORY_SEPARATOR . '*.js') as $file) {
    $name = basename($file);
    if (in_array($name, IGNORED_FILES, true)) {
        continue;
    }
    $hashes['js/' . $name] = 'sha512-' . base64_encode(
        hash('sha512', file_get_contents($file), true)
    );
}
if (count($hashes) === 0) {
    fail('No JS files found in ' . PATH . 'js');
}
ksort($hashes, SORT_STRING);

// find the 'sri' array in the configuration defaults
$file    = PATH . 'lib' . DIRECTORY_SEPARATOR . 'Configuration.php';
$content = file_get_contents($file);
if ($content === false) {
    fail('Could not read ' . $file);
}
if (preg_match(
    '#^( *)\'sri\' => \[\n(.*?)^\1\],\n#ms',
    $content, $matches, PREG_OFFSET_CAPTURE
) !== 1) {
    fail('Could not find the \'sri\' array in ' . $file);
}
$indent  = $matches[1][0] . '    ';
$block   = $matches[2][0];
$start   = $matches[2][1];
$current = [];
preg_match_all('#\'(js/[^\']+)\' *=> \'([^\']*)\',#', $block, $entries, PREG_SET_ORDER);
foreach ($entries as $entry) {
    $current[$entry[1]] = $entry[2];
}

// generate the new array content, aligning the arrows
$width = max(array_map('strlen', array_keys($hashes))) + 2;
$lines = '';
foreach ($hashes as $key => $hash) {
    $lines .= $indent . str_pad('\'' . $key . '\'', $width) . ' => \'' . $hash . '\',' . "\n";
}

// report the differences
$changes = 0;
foreach ($hashes as $key => $hash) {
    if (!array_key_exists($key, $current)) {
        echo 'added: ', $key, PHP_EOL;
        ++$changes;
    } elseif ($current[$key] !== $hash) {
        echo 'updated: ', $key, PHP_EOL;
        ++$changes;
    }
}
foreach (array_diff_key($current, $hashes) as $key => $hash) {
    echo 'removed: ', $key, PHP_EOL;
    ++$changes;
}
if ($lines === $block) {
    echo 'SRI hashes are up to date.', PHP_EOL;
    exit(0);
}
if ($check) {
    fail('SRI hashes in ' . $file . ' are outdated, run bin/sri to update them.', 1);
}
if ($changes === 0) {
    echo 'reformatted the \'sri\' array', PHP_EOL;
}
$content = substr($content, 0, $start) . $lines . substr($content, $start + strlen($block));
if (file_put_contents($file, $content) === false) {
    fail('Could not write ' . $file);
}

/**
 * print an error to STDERR and exit
 *
 * @param string $message
 * @param int $code
 */
function fail(string $message, int $code = 2): void
{
    fwrite(STDERR, $message . PHP_EOL);
    exit($code);
}