import "dart:convert";
import "package:dart_jsonwebtoken/dart_jsonwebtoken.dart";
import "package:matrixoidc/controllers/auth_code_controller.dart";
import "package:matrixoidc/controllers/key_controller.dart";
import "package:matrixoidc/controllers/settings_controller.dart";
import "package:shelf/shelf.dart";
import "package:http/http.dart" as http;
import "package:matrixoidc/models/matrix_user.dart";
import "package:riverpod/riverpod.dart";

class ApiHelper {
  final Ref ref;
  ApiHelper(this.ref);

  Future<Response> loginHandler(Request request) async {
    final body = await request.readAsString();
    final data = Uri.splitQueryString(body);

    final userId = data["user_id"];
    final accessToken = data["access_token"];
    final redirectUri = data["redirect_uri"];
    final state = data["state"] ?? "";

    if (userId == null || accessToken == null || redirectUri == null) {
      return Response(400, body: json.encode({"error": "Missing parameters"}));
    }

    final settings = ref.read(SettingsController.provider)!;
    final whoamiRes = await http.get(
      Uri.parse("${settings.homeserver}/_matrix/client/v3/account/whoami"),
      headers: {"Authorization": "Bearer $accessToken"},
    );

    if (whoamiRes.statusCode != 200) {
      return Response.forbidden(
        json.encode({"error": "Access token validation failed"}),
      );
    }

    final code = base64Url.encode(
      List<int>.generate(16, (_) => DateTime.now().millisecond % 256),
    );

    ref
        .read(AuthCodeController.provider.notifier)
        .set(
          code,
          MatrixUser(
            userId: userId,
            matrixToken: accessToken,
            nonce: data["nonce"],
          ),
        );

    final uri = Uri.parse(redirectUri);

    return Response.found(
      uri.replace(
        queryParameters: {
          ...uri.queryParameters,
          "code": code,
          "state": state,
          "nonce": data["nonce"],
        },
      ),
    );
  }

  Future<Response> bridgeHandler(Request request) async {
    final query = request.url.queryParameters;
    final code = query["code"];
    final redirectUri = query["redirect_uri"];

    if (code == null || redirectUri == null) {
      return Response(
        400,
        body: json.encode({"error": "Missing code or redirect_uri"}),
      );
    }

    final tokenRes = await tokenHandler(
      Request(
        "POST",
        Uri.base,
        body: utf8.encode("code=$code&client_id=proxy"),
      ),
    );

    if (tokenRes.statusCode != 200) {
      return Response(400, body: json.encode({"error": "Token post failed"}));
    }

    return Response.found(
      redirectUri,
      headers: {
        "set-cookie":
            "id_token=${json.decode(await tokenRes.readAsString())["id_token"]}; Path=/; Secure; HttpOnly; SameSite=Lax; Domain=.${ref.watch(SettingsController.provider)!.serviceDomain}; Max-Age=604800",
      },
    );
  }

  Future<Response> tokenHandler(Request request) async {
    final settings = ref.read(SettingsController.provider)!;
    final body = Uri.splitQueryString(await request.readAsString());
    final code = body["code"];
    final clientId = body["client_id"];

    if (code == null || clientId == null) {
      return Response(
        400,
        body: json.encode({"error": "Missing code or client_id"}),
      );
    }

    final codes = ref.read(AuthCodeController.provider);
    if (!codes.containsKey(code)) {
      return Response(400, body: json.encode({"error": "Invalid code"}));
    }

    final user = codes[code]!;
    ref.read(AuthCodeController.provider.notifier).remove(code);

    final jwt = JWT(
      {
        "exp":
            DateTime.now().add(Duration(days: 7)).millisecondsSinceEpoch ~/
            1000,
        "nonce": user.nonce,
        "iat": DateTime.now().millisecondsSinceEpoch ~/ 1000,
      },
      subject: user.userId,
      issuer: settings.issuer,
      audience: Audience([clientId]),
    );

    final token = jwt.sign(
      await ref.read(KeyController.provider.future),
      algorithm: JWTAlgorithm.HS256,
    );

    return Response.ok(
      json.encode({
        "id_token": token,
        "access_token": token,
        "token_type": "Bearer",
      }),
      headers: {"Content-Type": "application/json"},
    );
  }

  Future<Response> userinfoHandler(Request request) async {
    final auth = request.headers["authorization"];
    if (auth == null || !auth.startsWith("Bearer ")) {
      return Response.forbidden("No token");
    }

    try {
      final token = auth.substring(7);
      final jwt = JWT.verify(
        token,
        await ref.read(KeyController.provider.future),
      );

      final settings = ref.read(SettingsController.provider)!;
      final profile = await http.get(
        Uri.parse(
          "${settings.homeserver}/_matrix/client/v3/profile/${jwt.subject}",
        ),
      );

      if (profile.statusCode != 200) {
        return Response.forbidden(
          json.encode({"error": "Access token validation failed"}),
        );
      }

      final fullName = (json.decode(profile.body)["displayname"] as String);
      final name = fullName.length <= 20 ? fullName : fullName.substring(0, 20);

      return Response.ok(
        jsonEncode({
          "sub": jwt.subject,
          "name": name,
          "first_name": name,
          "last_name": "",
          "nickname": name,
        }),
        headers: {"Content-Type": "application/json"},
      );
    } catch (e) {
      return Response.forbidden("Invalid token");
    }
  }

  Future<Response> introspectionHandler(Request request) async {
    final token = Uri.splitQueryString(await request.readAsString())["token"];
    if (token == null) {
      return Response(400, body: json.encode({"error": "Missing token"}));
    }

    try {
      JWT.verify(token, await ref.read(KeyController.provider.future));

      return Response.ok(
        json.encode({"active": true}),
        headers: {"content-type": "application/json"},
      );
    } catch (_) {
      return Response.ok(
        json.encode({"active": false}),
        headers: {"content-type": "application/json"},
      );
    }
  }

  Future<Response> logoutHandler(Request request) async =>
      Response.ok(json.encode("Log out is not currently implemented"));

  Response openidConfiguration(_) {
    final settings = ref.read(SettingsController.provider)!;
    return Response.ok(
      json.encode({
        "issuer": settings.issuer,
        "authorization_endpoint": settings.authorizeEndpoint,
        "token_endpoint": "${settings.issuer}/token",
        "userinfo_endpoint": "${settings.issuer}/userinfo",
        "introspection_endpoint": "${settings.issuer}/introspect",
        "end_session_endpoint": "#",
        "response_types_supported": ["code"],
        "subject_types_supported": ["public"],
        "id_token_signing_alg_values_supported": ["HS256"],
      }),
      headers: {"Content-Type": "application/json"},
    );
  }

  static final provider = Provider<ApiHelper>(ApiHelper.new);
}