dart_pkpass/lib/pkpass/pass_file.dart

import 'dart:convert';
import 'dart:typed_data';

import 'package:archive/archive.dart';
import 'package:charset/charset.dart';
import 'package:crypto/crypto.dart';
import 'package:intl/locale.dart';

import 'package:pkpass/pkpass.dart';
import 'package:pkpass/pkpass/utils/file_matcher.dart';
import 'package:pkpass/pkpass/utils/lproj_parser.dart';

class PassFile {
  const PassFile(this.metadata, this._folder);

  static Future<PassFile> parse(Uint8List pass) async {
    final codec = ZipDecoder();
    Archive archive;
    try {
      archive = codec.decodeBytes(pass);
    } catch (e) {
      throw InvalidEncodingError();
    }

    Map<String, String> manifest;

    final file =
        archive.files.singleWhere((element) => element.name == 'manifest.json');
    manifest = (json.decode(file.stringContent) as Map).cast<String, String>();

    final folder = <ArchiveFile>[];

    await Future.wait(
      manifest.entries.map(
        (manifestEntry) async {
          final file = archive.files
              .singleWhere((element) => element.name == manifestEntry.key);

          final content = file.readBytes();
          if (content == null) {
            return;
          }

          String hash = sha1.convert(content).toString();

          final checksum = manifestEntry.value;

          if (hash != checksum) {
            throw ManifestChecksumError(expected: checksum, actual: hash);
          }

          folder.add(file);
        },
      ),
    );

    final passFile =
        archive.singleWhere((element) => element.name == 'pass.json');

    final PassMetadata metadata = PassMetadata.fromJson(
      json.decode(passFile.stringContent) as Map<String, Object?>,
    );

    return PassFile(metadata, folder);
  }

  final PassMetadata metadata;

  final List<ArchiveFile> _folder;

  Uint8List? _matchUint8ListFile({
    required String name,
    required Locale? locale,
    required int scale,
  }) {
    final files = _folder.map((e) => e.name).toList();
    final path = FileMatcher.matchFile(
      files: files,
      name: name,
      scale: scale,
      locale: locale,
      extension: 'png',
    );
    if (path == null) return null;
    final file = _folder.singleWhere((element) => element.name == path);
    final content = file.readBytes();
    return content;
  }

  Uint8List? getBackground({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'background', locale: locale, scale: scale);

  Uint8List? getFooter({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'footer', locale: locale, scale: scale);

  Uint8List? getIcon({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'icon', locale: locale, scale: scale);

  Uint8List? getLogo({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'logo', locale: locale, scale: scale);

  Uint8List? getStrip({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'strip', locale: locale, scale: scale);

  Uint8List? getThumbnail({Locale? locale, int scale = 1}) =>
      _matchUint8ListFile(name: 'thumbnail', locale: locale, scale: scale);

  Map<String, String>? getLocalizations(Locale? locale) {
    final files = _folder.map((e) => e.name).toList();
    final paths = FileMatcher.matchLocale(
      files: files,
      name: 'pass',
      extension: 'strings',
      locale: locale,
    );
    if (paths.isEmpty) return null;
    final file = _folder.singleWhere((element) => element.name == paths.first);
    return LProjParser.parse(file.stringContent);
  }
}

extension on ArchiveFile {
  String get stringContent {
    final codec = Charset.detect(
          readBytes()!,
          defaultEncoding: utf8,
          orders: [
            utf8,
            ascii,
            gbk,
            latin1,
            utf16,
          ],
        ) ??
        utf8;
    try {
      return codec.decode(content);
    } on FormatException {
      // utf8 and utf16 are hard to distinguish
      if (codec is Utf8Codec) {
        return utf16.decode(content);
      }
      rethrow;
    }
  }
}