import 'dart:convert';
import 'dart:io';

import 'package:http/http.dart' as http;

class Release {
  final String version;
  final String date;

  Release({required this.version, required this.date});
}

enum CPUArchitecture {
  x86_64('x86_64', 'x64'),
  aarch64('aarch64', 'arm64');

  final String flatpakArchCode;
  final String flutterDirName;
  const CPUArchitecture(this.flatpakArchCode, this.flutterDirName);
}

class ReleaseAsset {
  final CPUArchitecture arch;
  final String tarballUrlOrPath;
  final bool isRelativeLocalPath;
  final String tarballSha256;

  ReleaseAsset(
      {required this.arch,
      required this.tarballUrlOrPath,
      required this.isRelativeLocalPath,
      required this.tarballSha256});
}

class Icon {
  static const _symbolicType = 'symbolic';
  final String type;
  final String path;
  late final String _fileExtension;

  Icon({required this.type, required this.path}) {
    _fileExtension = path.split('.').last;
  }

  String getFilename(String appId) => (type == _symbolicType)
      ? '$appId-symbolic.$_fileExtension'
      : '$appId.$_fileExtension';
}

class GithubReleases {
  final String githubReleaseOrganization;
  final String githubReleaseProject;
  List<Release>? _releases;
  List<ReleaseAsset>? _latestReleaseAssets;

  GithubReleases(this.githubReleaseOrganization, this.githubReleaseProject);

  Future<List<Release>> getReleases(bool canBeEmpty) async {
    if (_releases == null) {
      await _fetchReleasesAndAssets(canBeEmpty);
    }
    return _releases!;
  }

  Future<List<ReleaseAsset>?> getLatestReleaseAssets() async {
    if (_releases == null) {
      await _fetchReleasesAndAssets(false);
    }
    return _latestReleaseAssets;
  }

  Future<void> _fetchReleasesAndAssets(bool canBeEmpty) async {
    final releaseJsonContent = (await http.get(Uri(
            scheme: 'https',
            host: 'api.github.com',
            path:
                '/repos/$githubReleaseOrganization/$githubReleaseProject/releases')))
        .body;
    final decodedJson = jsonDecode(releaseJsonContent) as List;

    DateTime? latestReleaseAssetDate;

    final releases = List<Release>.empty(growable: true);

    await Future.forEach<dynamic>(decodedJson, (dynamic releaseDynamic) async {
      final releaseMap = releaseDynamic as Map;

      final releaseDateAndTime =
          DateTime.parse(releaseMap['published_at'] as String);
      final releaseDateString =
          releaseDateAndTime.toIso8601String().split('T').first;

      if (latestReleaseAssetDate == null ||
          (latestReleaseAssetDate?.compareTo(releaseDateAndTime) == -1)) {
        final assets =
            await _parseGithubReleaseAssets(releaseMap['assets'] as List);
        if (assets != null) {
          _latestReleaseAssets = assets;
          latestReleaseAssetDate = releaseDateAndTime;
        }
      }

      releases.add(Release(
          version: releaseMap['name'] as String, date: releaseDateString));
    });

    if (releases.isNotEmpty || canBeEmpty) {
      _releases = releases;
    } else {
      throw Exception("Github must contain at least 1 release.");
    }
  }

  Future<List<ReleaseAsset>?> _parseGithubReleaseAssets(List assetMaps) async {
    String? x64TarballUrl;
    String? x64Sha;
    String? aarch64TarballUrl;
    String? aarch64Sha;
    for (final am in assetMaps) {
      final amMap = am as Map;

      final downloadUrl = amMap['browser_download_url'] as String;
      final filename = amMap['name'] as String;
      final fileExtension = filename.substring(filename.indexOf('.') + 1);
      final filenameWithoutExtension =
          filename.substring(0, filename.indexOf('.'));

      final arch = filenameWithoutExtension.endsWith('aarch64')
          ? CPUArchitecture.aarch64
          : CPUArchitecture.x86_64;

      switch (fileExtension) {
        case 'sha256':
          if (arch == CPUArchitecture.aarch64) {
            aarch64Sha = await _readSha(downloadUrl);
          } else {
            x64Sha = await _readSha(downloadUrl);
          }
          break;
        case 'tar':
        case 'tar.gz':
        case 'tgz':
        case 'tar.xz':
        case 'txz':
        case 'tar.bz2':
        case 'tbz2':
        case 'zip':
        case '7z':
          if (arch == CPUArchitecture.aarch64) {
            aarch64TarballUrl = downloadUrl;
          } else {
            x64TarballUrl = downloadUrl;
          }
          break;
        default:
          break;
      }
    }
    final res = List<ReleaseAsset>.empty(growable: true);
    if (x64TarballUrl != null && x64Sha != null) {
      res.add(ReleaseAsset(
          arch: CPUArchitecture.x86_64,
          tarballUrlOrPath: x64TarballUrl,
          isRelativeLocalPath: false,
          tarballSha256: x64Sha));
    }
    if (aarch64TarballUrl != null && aarch64Sha != null) {
      res.add(ReleaseAsset(
          arch: CPUArchitecture.aarch64,
          tarballUrlOrPath: aarch64TarballUrl,
          isRelativeLocalPath: false,
          tarballSha256: aarch64Sha));
    }
    return res.isEmpty ? null : res;
  }

  Future<String> _readSha(String shaUrl) async =>
      (await http.get(Uri.parse(shaUrl))).body.split(' ').first;
}

class FlatpakMeta {
  final String appId;
  final String lowercaseAppName;
  final String appStreamPath;
  final String desktopPath;
  final List<Icon> icons;

  // Flatpak manifest releated properties
  final String freedesktopRuntime;
  final List<String>? buildCommandsAfterUnpack;
  final List<dynamic>? extraModules;
  final List<String> finishArgs;

  // Properties relevant only for local releases
  final List<Release>? _localReleases;
  final List<ReleaseAsset>? _localReleaseAssets;
  final String localLinuxBuildDir;

  // Properties relevant only for releases fetched from Github
  final String? githubReleaseOrganization;
  final String? githubReleaseProject;
  late final GithubReleases? _githubReleases;

  FlatpakMeta(
      {required this.appId,
      required this.lowercaseAppName,
      required this.githubReleaseOrganization,
      required this.githubReleaseProject,
      required List<Release>? localReleases,
      required List<ReleaseAsset>? localReleaseAssets,
      required this.localLinuxBuildDir,
      required this.appStreamPath,
      required this.desktopPath,
      required this.icons,
      required this.freedesktopRuntime,
      required this.buildCommandsAfterUnpack,
      required this.extraModules,
      required this.finishArgs})
      : _localReleases = localReleases,
        _localReleaseAssets = localReleaseAssets {
    if (githubReleaseOrganization != null && githubReleaseProject != null) {
      _githubReleases =
          GithubReleases(githubReleaseOrganization!, githubReleaseProject!);
    }
  }

  Future<List<Release>> getReleases(
      bool fetchReleasesFromGithub, String? addedTodaysVersion) async {
    final releases = List<Release>.empty(growable: true);
    if (addedTodaysVersion != null) {
      releases.add(Release(
          version: addedTodaysVersion,
          date: DateTime.now().toIso8601String().split("T").first));
    }
    if (fetchReleasesFromGithub) {
      if (_githubReleases == null) {
        throw Exception(
            'Metadata must include Github repository info if fetching releases from Github.');
      }
      releases.addAll(
          await _githubReleases!.getReleases(addedTodaysVersion != null));
    } else {
      if (_localReleases == null && addedTodaysVersion == null) {
        throw Exception(
            'Metadata must include releases if not fetching releases from Github.');
      }
      if (_localReleases?.isNotEmpty ?? false) {
        releases.addAll(_localReleases!);
      }
    }
    return releases;
  }

  Future<List<ReleaseAsset>?> getLatestReleaseAssets(
      bool fetchReleasesFromGithub) async {
    if (fetchReleasesFromGithub) {
      if (_githubReleases == null) {
        throw Exception(
            'Metadata must include Github repository info if fetching releases from Github.');
      }
      return await _githubReleases!.getLatestReleaseAssets();
    } else {
      if (_localReleases == null) {
        throw Exception(
            'Metadata must include releases if not fetching releases from Github.');
      }
      return _localReleaseAssets;
    }
  }

  static FlatpakMeta fromJson(File jsonFile, {bool skipLocalReleases = false}) {
    try {
      final dynamic json = jsonDecode(jsonFile.readAsStringSync());
      return FlatpakMeta(
          appId: json['appId'] as String,
          lowercaseAppName: json['lowercaseAppName'] as String,
          githubReleaseOrganization:
              json['githubReleaseOrganization'] as String?,
          githubReleaseProject: json['githubReleaseProject'] as String?,
          localReleases: skipLocalReleases
              ? null
              : (json['localReleases'] as List?)?.map((dynamic r) {
                  final rMap = r as Map;
                  return Release(
                      version: rMap['version'] as String,
                      date: rMap['date'] as String);
                }).toList(),
          localReleaseAssets: skipLocalReleases
              ? null
              : (json['localReleaseAssets'] as List?)?.map((dynamic ra) {
                  final raMap = ra as Map;
                  final archString = raMap['arch'] as String;
                  final arch = (archString ==
                          CPUArchitecture.x86_64.flatpakArchCode)
                      ? CPUArchitecture.x86_64
                      : (archString == CPUArchitecture.aarch64.flatpakArchCode)
                          ? CPUArchitecture.aarch64
                          : null;
                  if (arch == null) {
                    throw Exception(
                        'Architecture must be either "${CPUArchitecture.x86_64.flatpakArchCode}" or "${CPUArchitecture.aarch64.flatpakArchCode}"');
                  }
                  final tarballFile = File(
                      '${jsonFile.parent.path}/${raMap['tarballPath'] as String}');
                  final tarballPath = tarballFile.absolute.path;
                  final preShasum =
                      Process.runSync('shasum', ['-a', '256', tarballPath]);
                  final shasum = preShasum.stdout.toString().split(' ').first;
                  if (preShasum.exitCode != 0) {
                    throw Exception(preShasum.stderr);
                  }
                  return ReleaseAsset(
                      arch: arch,
                      tarballUrlOrPath: tarballPath,
                      isRelativeLocalPath: true,
                      tarballSha256: shasum);
                }).toList(),
          localLinuxBuildDir: json['localLinuxBuildDir'] as String,
          appStreamPath: json['appStreamPath'] as String,
          desktopPath: json['desktopPath'] as String,
          icons: (json['icons'] as Map).entries.map((mapEntry) {
            return Icon(
                type: mapEntry.key as String, path: mapEntry.value as String);
          }).toList(),
          freedesktopRuntime: json['freedesktopRuntime'] as String,
          buildCommandsAfterUnpack: (json['buildCommandsAfterUnpack'] as List?)
              ?.map((dynamic bc) => bc as String)
              .toList(),
          extraModules: json['extraModules'] as List?,
          finishArgs: (json['finishArgs'] as List)
              .map((dynamic fa) => fa as String)
              .toList());
    } catch (e) {
      throw Exception('Could not parse JSON file, due to this error:\n$e');
    }
  }
}