import 'dart:io';
import 'dart:typed_data';

import 'package:archive/archive_io.dart';

/// Packs a directory of static files into a gzip-compressed tar archive
/// (contents at the archive root) for a single-shot upload + remote extract.
class WebArchive {
  /// Returns the .tar.gz bytes of [dir]'s contents and the number of files.
  static (Uint8List, int) tarGz(Directory dir) {
    final archive = createArchiveFromDirectory(dir, includeDirName: false);
    // CRITICAL: on Windows the entry names use backslashes; a POSIX `tar` on
    // the server would then create single files literally named
    // `assets\main.js` instead of the `assets/main.js` tree — breaking any
    // app with subdirectories (Angular/React assets, etc.). Force forward
    // slashes so the archive is valid on Linux.
    for (final f in archive.files) {
      f.name = f.name.replaceAll('\\', '/');
    }
    final tar = TarEncoder().encode(archive);
    final gz = GZipEncoder().encode(tar);
    final count = archive.files.where((f) => f.isFile).length;
    // Release the file handles opened while reading the directory so the
    // source tree isn't left locked (notably on Windows).
    for (final f in archive.files) {
      f.closeSync();
    }
    return (Uint8List.fromList(gz), count);
  }
}

/// Top-level entry so packaging can run off the UI isolate via `compute`.
(Uint8List, int) packageWebDir(String path) =>
    WebArchive.tarGz(Directory(path));