<?php
/**
 * Migrationsskript: Wandelt inline Base64-Bilder in
 * knowledgecenter_post_versions.content in echte Dateien um.
 *
 * CLI-only. Idempotent. Per-Version-Transaktion mit Backup-Tabelle.
 *
 * Aufruf:
 *   php migrate_base64_to_files.php --dry-run --post-id=417 --verbose
 *   php migrate_base64_to_files.php --apply  --post-id=417
 *   php migrate_base64_to_files.php --apply
 *
 * Optionen:
 *   --dry-run            Standard. Nur analysieren, nichts schreiben.
 *   --apply              Wirklich migrieren (Dateien + DB).
 *   --post-id=N          Nur Versionen dieses Posts.
 *   --version-id=N       Genau diese Version.
 *   --limit=N            Maximal N Versionen verarbeiten.
 *   --verbose            Mehr Details ins Log.
 *   --help               Diese Hilfe.
 */

if (PHP_SAPI !== 'cli') {
    fwrite(STDERR, "Dieses Skript ist CLI-only.\n");
    exit(2);
}

$currDir   = __DIR__;
$rootDir   = dirname(dirname(dirname($currDir)));
$mysydeDir = $rootDir . '/mysyde';

require_once($rootDir . '/vendor/autoload.php');

$envDir      = $rootDir . '/config';
$envFilePath = $envDir . '/.env';
if (is_dir($envDir) && file_exists($envFilePath) && is_file($envFilePath) && is_readable($envFilePath)) {
    $dotenv = new \Dotenv\Dotenv($envDir);
    $dotenv->load();
}

require_once($mysydeDir . '/common/common_functions.inc.php');
$connEnv = (local_environment()) ? $mysydeDir . '/dc.config.php' : $mysydeDir . '/dc-server.config.php';
require_once($connEnv);
db_connect();

// ------- Args -------
$opts = [
    'dry-run' => true,
    'apply'   => false,
    'post-id' => null,
    'version-id' => null,
    'limit'   => null,
    'verbose' => false,
];
foreach (array_slice($argv, 1) as $arg) {
    if ($arg === '--help' || $arg === '-h') {
        echo "Usage: php migrate_base64_to_files.php [--dry-run|--apply] [--post-id=N] [--version-id=N] [--limit=N] [--verbose]\n";
        exit(0);
    }
    if ($arg === '--apply')    { $opts['apply'] = true; $opts['dry-run'] = false; continue; }
    if ($arg === '--dry-run')  { $opts['dry-run'] = true; $opts['apply'] = false; continue; }
    if ($arg === '--verbose')  { $opts['verbose'] = true; continue; }
    if (preg_match('/^--post-id=(\d+)$/', $arg, $m))    { $opts['post-id'] = (int) $m[1]; continue; }
    if (preg_match('/^--version-id=(\d+)$/', $arg, $m)) { $opts['version-id'] = (int) $m[1]; continue; }
    if (preg_match('/^--limit=(\d+)$/', $arg, $m))      { $opts['limit'] = (int) $m[1]; continue; }
    fwrite(STDERR, "Unbekannte Option: $arg\n");
    exit(2);
}

$dryRun  = !$opts['apply'];
$verbose = $opts['verbose'];
$runId   = bin2hex(random_bytes(8));

// ------- Logging -------
$logDir = $rootDir . '/userdata/knowledgecenter_update/migrations';
if (!is_dir($logDir) && !@mkdir($logDir, 0775, true)) {
    fwrite(STDERR, "Log-Verzeichnis nicht anlegbar: $logDir\n");
    exit(3);
}
$logFile = $logDir . '/base64_to_files_' . gmdate('Ymd_His') . '_' . $runId . '.log';
$logFp = fopen($logFile, 'w');
if (!$logFp) {
    fwrite(STDERR, "Log-Datei nicht öffenbar: $logFile\n");
    exit(3);
}

function logmsg($msg, $level = 'INFO') {
    global $logFp, $verbose;
    $line = '[' . gmdate('Y-m-d H:i:s') . " UTC] [$level] $msg\n";
    fwrite($logFp, $line);
    if ($verbose || in_array($level, ['ERROR', 'FAIL', 'OK', 'WARN', 'HEAD'], true)) {
        fwrite(STDOUT, $line);
    }
}

logmsg("Migration-Run gestartet. run_id=$runId  mode=" . ($dryRun ? 'DRY-RUN' : 'APPLY')
       . "  post-id=" . ($opts['post-id'] ?? 'ALL')
       . "  version-id=" . ($opts['version-id'] ?? 'ALL')
       . "  limit=" . ($opts['limit'] ?? 'unbeschränkt'), 'HEAD');

// ------- Backup-Tabelle anlegen -------
$createBackup = "CREATE TABLE IF NOT EXISTS knowledgecenter_post_versions_migration_backup (
    id INT AUTO_INCREMENT PRIMARY KEY,
    version_id INT NOT NULL,
    post_id INT NOT NULL,
    language_id INT NOT NULL,
    version_number INT NOT NULL,
    original_content LONGTEXT NOT NULL,
    original_length INT NOT NULL,
    images_extracted INT NOT NULL,
    migrated_at DATETIME NOT NULL,
    script_run_id VARCHAR(32) NOT NULL,
    UNIQUE KEY uniq_version_run (version_id, script_run_id),
    KEY idx_run (script_run_id),
    KEY idx_post (post_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4";
if (!mysqli_query($GLOBALS['mysql_con'], $createBackup)) {
    logmsg('Backup-Tabelle konnte nicht angelegt werden: ' . mysqli_error($GLOBALS['mysql_con']), 'ERROR');
    exit(4);
}

// ------- Kandidaten finden -------
$where = ["content LIKE '%data:image/%;base64,%'"];
if ($opts['post-id'] !== null)    $where[] = "post_id = " . (int) $opts['post-id'];
if ($opts['version-id'] !== null) $where[] = "id = " . (int) $opts['version-id'];
$sql = "SELECT id, post_id, language_id, version_number, content
        FROM knowledgecenter_post_versions
        WHERE " . implode(' AND ', $where) . "
        ORDER BY post_id, language_id, version_number";
if ($opts['limit'] !== null) $sql .= " LIMIT " . (int) $opts['limit'];

$res = mysqli_query($GLOBALS['mysql_con'], $sql);
if (!$res) {
    logmsg('Query fehlgeschlagen: ' . mysqli_error($GLOBALS['mysql_con']), 'ERROR');
    exit(5);
}
$candidateCount = mysqli_num_rows($res);
logmsg("Gefundene Kandidaten: $candidateCount", 'HEAD');

// ------- Helper -------
function mime_to_ext($mime) {
    static $map = [
        'image/jpeg' => 'jpg',
        'image/png'  => 'png',
        'image/gif'  => 'gif',
        'image/webp' => 'webp',
    ];
    return isset($map[$mime]) ? $map[$mime] : null;
}

function ensure_post_inline_dir($rootDir, $postId, $dryRun) {
    $hash    = substr(sha1('kc_post_' . (int) $postId), 0, 24);
    $relBase = 'knowledgecenter_update/posts/' . $hash;
    $absBase = $rootDir . '/userdata/' . $relBase;
    $absInline = $absBase . '/inline';
    if ($dryRun) {
        return ['hash' => $hash, 'relBase' => $relBase, 'absBase' => $absBase, 'absInline' => $absInline, 'created' => false];
    }
    if (!is_dir($absBase) && !@mkdir($absBase, 0775, true)) {
        throw new RuntimeException("Post-Ordner nicht anlegbar: $absBase");
    }
    $sharedLink = $absBase . '/shared';
    if (!is_link($sharedLink) && !file_exists($sharedLink)) {
        @symlink('../../shared', $sharedLink);
    }
    if (!is_dir($absInline) && !@mkdir($absInline, 0775, true)) {
        throw new RuntimeException("Inline-Ordner nicht anlegbar: $absInline");
    }
    return ['hash' => $hash, 'relBase' => $relBase, 'absBase' => $absBase, 'absInline' => $absInline, 'created' => true];
}

function process_version($row, $rootDir, $dryRun, $runId, $verbose) {
    $versionId = (int) $row['id'];
    $postId    = (int) $row['post_id'];
    $langId    = (int) $row['language_id'];
    $verNum    = (int) $row['version_number'];
    $content   = (string) $row['content'];
    $origLen   = strlen($content);

    $tag = "version_id=$versionId post_id=$postId lang=$langId v=$verNum";

    // DOM laden
    $wrapped = '<?xml encoding="UTF-8"?><div id="kc_root">' . $content . '</div>';
    $prev = libxml_use_internal_errors(true);
    $dom = new DOMDocument();
    $loaded = $dom->loadHTML($wrapped, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD | LIBXML_NOERROR | LIBXML_NOWARNING);
    libxml_clear_errors();
    libxml_use_internal_errors($prev);
    if (!$loaded) {
        logmsg("[FAIL] $tag DOM load fehlgeschlagen", 'FAIL');
        return ['ok' => false, 'rewrote' => 0];
    }

    $root = $dom->getElementById('kc_root');
    if (!$root) {
        logmsg("[FAIL] $tag wrapper nicht gefunden", 'FAIL');
        return ['ok' => false, 'rewrote' => 0];
    }

    $imgs = $dom->getElementsByTagName('img');
    $imgList = [];
    foreach ($imgs as $img) { $imgList[] = $img; }

    $rewrote = 0;
    $skippedNoBase64 = 0;
    $skippedBadDecode = 0;
    $skippedBadMime = 0;
    $skippedTooBig = 0;
    $skippedSrcset = 0;
    $totalBytesIn = 0;

    foreach ($imgList as $img) {
        if ($img->hasAttribute('srcset')) {
            $skippedSrcset++;
            logmsg("[WARN] $tag <img srcset=...> belassen", 'WARN');
            continue;
        }
        $src = $img->getAttribute('src');
        if ($src === '' || strncmp($src, 'data:', 5) !== 0) continue;

        if (!preg_match('#^data:(image/[a-z0-9.+-]+)?(;charset=[^;,]+)?(;base64)?,(.*)$#is', $src, $m)) {
            $skippedNoBase64++;
            logmsg("[WARN] $tag data-URI nicht parsbar, belassen", 'WARN');
            continue;
        }
        $declaredMime = strtolower($m[1] ?? '');
        $isBase64     = !empty($m[3]);
        $payload      = $m[4];

        if (!$isBase64) {
            $skippedNoBase64++;
            logmsg("[WARN] $tag data-URI ohne ;base64, belassen", 'WARN');
            continue;
        }
        $decoded = base64_decode($payload, true);
        if ($decoded === false || $decoded === '') {
            $skippedBadDecode++;
            logmsg("[WARN] $tag base64 nicht dekodierbar, belassen", 'WARN');
            continue;
        }

        $size = strlen($decoded);
        $totalBytesIn += $size;
        if ($size > 5 * 1024 * 1024) {
            $skippedTooBig++;
            logmsg("[WARN] $tag Bild > 5MB ($size bytes), belassen", 'WARN');
            continue;
        }

        $finfo = finfo_open(FILEINFO_MIME_TYPE);
        $detectedMime = $finfo ? finfo_buffer($finfo, $decoded) : false;
        if ($finfo) finfo_close($finfo);
        $ext = mime_to_ext($detectedMime);
        if (!$ext) {
            $skippedBadMime++;
            logmsg("[WARN] $tag Mime '$detectedMime' nicht erlaubt (declared='$declaredMime'), belassen", 'WARN');
            continue;
        }

        $dir = ensure_post_inline_dir($rootDir, $postId, $dryRun);
        $sha = hash('sha256', $decoded);
        $filename  = $sha . '.' . $ext;
        $finalPath = $dir['absInline'] . '/' . $filename;
        $publicUrl = '/userdata/' . $dir['relBase'] . '/inline/' . $filename;

        if ($dryRun) {
            if ($verbose) logmsg("[DRY ] $tag would write $finalPath ($size bytes) → $publicUrl", 'INFO');
        } else {
            $writeNeeded = true;
            if (file_exists($finalPath)) {
                $existingSize = filesize($finalPath);
                if ($existingSize === $size) {
                    $writeNeeded = false;
                    if ($verbose) logmsg("[INFO] $tag dedup hit $finalPath", 'INFO');
                } else {
                    logmsg("[WARN] $tag SHA-Kollision?! $finalPath bestehend=$existingSize bytes, neu=$size bytes – überspringe", 'WARN');
                    $writeNeeded = false;
                }
            }
            if ($writeNeeded) {
                $tmp = $dir['absInline'] . '/.tmp_' . bin2hex(random_bytes(6));
                if (file_put_contents($tmp, $decoded) === false) {
                    logmsg("[FAIL] $tag konnte tmp-Datei nicht schreiben", 'FAIL');
                    return ['ok' => false, 'rewrote' => $rewrote];
                }
                @chmod($tmp, 0664);
                if (!rename($tmp, $finalPath)) {
                    @unlink($tmp);
                    logmsg("[FAIL] $tag rename failed", 'FAIL');
                    return ['ok' => false, 'rewrote' => $rewrote];
                }
            }
        }

        $img->setAttribute('src', $publicUrl);
        $rewrote++;
    }

    // Serialisieren
    $newContent = '';
    foreach ($root->childNodes as $child) {
        $newContent .= $dom->saveHTML($child);
    }

    $newLen = strlen($newContent);
    $report = sprintf(
        "%s images_rewritten=%d skipped(no_b64=%d bad_decode=%d bad_mime=%d too_big=%d srcset=%d) from_kb=%d to_kb=%d",
        $tag, $rewrote, $skippedNoBase64, $skippedBadDecode, $skippedBadMime, $skippedTooBig, $skippedSrcset,
        (int) round($origLen / 1024), (int) round($newLen / 1024)
    );

    return [
        'ok'        => true,
        'rewrote'   => $rewrote,
        'newContent'=> $newContent,
        'origLen'   => $origLen,
        'newLen'    => $newLen,
        'report'    => $report,
    ];
}

// ------- Verarbeitung -------
$totals = ['ok' => 0, 'rewritten_images' => 0, 'fail' => 0, 'no_change' => 0, 'bytes_saved' => 0];

while ($row = mysqli_fetch_assoc($res)) {
    $versionId = (int) $row['id'];
    $postId    = (int) $row['post_id'];

    if (!$dryRun) mysqli_query($GLOBALS['mysql_con'], 'START TRANSACTION');
    try {
        $result = process_version($row, $rootDir, $dryRun, $runId, $verbose);
    } catch (Throwable $e) {
        if (!$dryRun) mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[FAIL] version_id=$versionId Exception: " . $e->getMessage(), 'FAIL');
        $totals['fail']++;
        continue;
    }
    if (!$result['ok']) {
        if (!$dryRun) mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        $totals['fail']++;
        continue;
    }

    if ($result['rewrote'] === 0) {
        if (!$dryRun) mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[SKIP] " . $result['report'] . " (kein <img> umgeschrieben)", 'WARN');
        $totals['no_change']++;
        continue;
    }

    if ($dryRun) {
        logmsg("[DRY ] " . $result['report'], 'OK');
        $totals['ok']++;
        $totals['rewritten_images'] += $result['rewrote'];
        $totals['bytes_saved'] += max(0, $result['origLen'] - $result['newLen']);
        continue;
    }

    // Backup + UPDATE
    $stmt = mysqli_prepare(
        $GLOBALS['mysql_con'],
        "INSERT INTO knowledgecenter_post_versions_migration_backup
         (version_id, post_id, language_id, version_number, original_content, original_length, images_extracted, migrated_at, script_run_id)
         VALUES (?, ?, ?, ?, ?, ?, ?, NOW(), ?)"
    );
    if (!$stmt) {
        mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[FAIL] version_id=$versionId backup-prepare: " . mysqli_error($GLOBALS['mysql_con']), 'FAIL');
        $totals['fail']++;
        continue;
    }
    $verId    = (int) $row['id'];
    $pId      = (int) $row['post_id'];
    $lId      = (int) $row['language_id'];
    $vNum     = (int) $row['version_number'];
    $origCt   = (string) $row['content'];
    $origLen  = $result['origLen'];
    $rewrote  = $result['rewrote'];
    mysqli_stmt_bind_param($stmt, 'iiiisiis', $verId, $pId, $lId, $vNum, $origCt, $origLen, $rewrote, $runId);
    if (!mysqli_stmt_execute($stmt)) {
        mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[FAIL] version_id=$versionId backup-insert: " . mysqli_stmt_error($stmt), 'FAIL');
        mysqli_stmt_close($stmt);
        $totals['fail']++;
        continue;
    }
    mysqli_stmt_close($stmt);

    $stmt2 = mysqli_prepare(
        $GLOBALS['mysql_con'],
        "UPDATE knowledgecenter_post_versions SET content = ? WHERE id = ?"
    );
    if (!$stmt2) {
        mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[FAIL] version_id=$versionId update-prepare: " . mysqli_error($GLOBALS['mysql_con']), 'FAIL');
        $totals['fail']++;
        continue;
    }
    $newCt = $result['newContent'];
    mysqli_stmt_bind_param($stmt2, 'si', $newCt, $verId);
    if (!mysqli_stmt_execute($stmt2)) {
        mysqli_query($GLOBALS['mysql_con'], 'ROLLBACK');
        logmsg("[FAIL] version_id=$versionId update-exec: " . mysqli_stmt_error($stmt2), 'FAIL');
        mysqli_stmt_close($stmt2);
        $totals['fail']++;
        continue;
    }
    mysqli_stmt_close($stmt2);

    if (!mysqli_query($GLOBALS['mysql_con'], 'COMMIT')) {
        logmsg("[FAIL] version_id=$versionId COMMIT-Fehler: " . mysqli_error($GLOBALS['mysql_con']), 'FAIL');
        $totals['fail']++;
        continue;
    }

    logmsg("[OK  ] " . $result['report'], 'OK');
    $totals['ok']++;
    $totals['rewritten_images'] += $result['rewrote'];
    $totals['bytes_saved'] += max(0, $result['origLen'] - $result['newLen']);
}

logmsg(sprintf(
    "Fertig. ok=%d  fail=%d  no_change=%d  rewritten_images=%d  bytes_saved=%d (%.2f MB)  mode=%s",
    $totals['ok'], $totals['fail'], $totals['no_change'], $totals['rewritten_images'],
    $totals['bytes_saved'], $totals['bytes_saved'] / 1024 / 1024,
    $dryRun ? 'DRY-RUN' : 'APPLY'
), 'HEAD');
logmsg("Log-Datei: $logFile", 'HEAD');

fclose($logFp);
exit($totals['fail'] > 0 ? 1 : 0);