import 'dart:async';
import 'package:dartz/dartz.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:shlink_app/API/Classes/ShlinkStats/shlink_stats.dart';
import 'package:shlink_app/API/Classes/ShortURL/short_url.dart';
import 'package:shlink_app/API/Classes/ShortURLSubmission/short_url_submission.dart';
import 'package:shlink_app/API/Methods/connect.dart';
import 'package:shlink_app/API/Methods/get_recent_short_urls.dart';
import 'package:shlink_app/API/Methods/get_server_health.dart';
import 'package:shlink_app/API/Methods/get_shlink_stats.dart';
import 'package:shlink_app/API/Methods/get_short_urls.dart';
import 'package:shlink_app/API/Methods/update_short_url.dart';

import 'Methods/delete_short_url.dart';
import 'Methods/submit_short_url.dart';

class ServerManager {
  /// The URL of the Shlink server
  String? serverUrl;

  /// The API key to access the server
  String? apiKey;

  /// Current Shlink API Version used by the app
  static String apiVersion = "3";

  String getServerUrl() {
    return serverUrl ?? "";
  }

  String getApiVersion() {
    return apiVersion;
  }

  /// Checks whether the user provided information about the server
  /// (url and apikey)
  Future<bool> checkLogin() async {
    await _loadCredentials();
    return (serverUrl != null);
  }

  /// Logs out the user and removes data about the Shlink server
  Future<void> logOut() async {
    const storage = FlutterSecureStorage();
    await storage.delete(key: "shlink_url");
    await storage.delete(key: "shlink_apikey");
  }

  /// Loads the server credentials from [FlutterSecureStorage]
  Future<void> _loadCredentials() async {
    const storage = FlutterSecureStorage();
    final prefs = await SharedPreferences.getInstance();

    if (prefs.getBool('first_run') ?? true) {
      FlutterSecureStorage storage = const FlutterSecureStorage();

      await storage.deleteAll();

      prefs.setBool('first_run', false);
    }
    serverUrl = await storage.read(key: "shlink_url");
    apiKey = await storage.read(key: "shlink_apikey");
  }

  /// Saves the provided server credentials to [FlutterSecureStorage]
  void _saveCredentials(String url, String apiKey) async {
    const storage = FlutterSecureStorage();
    storage.write(key: "shlink_url", value: url);
    storage.write(key: "shlink_apikey", value: apiKey);
  }

  /// Saves provided server credentials and tries to establish a connection
  FutureOr<Either<String, Failure>> initAndConnect(
      String url, String apiKey) async {
    // TODO: convert url to correct format
    serverUrl = url;
    this.apiKey = apiKey;
    _saveCredentials(url, apiKey);
    final result = await connect();
    result.fold((l) => null, (r) {
      logOut();
    });
    return result;
  }

  /// Establishes a connection to the server
  FutureOr<Either<String, Failure>> connect() async {
    _loadCredentials();
    return apiConnect(apiKey, serverUrl, apiVersion);
  }

  /// Gets all short URLs from the server
  FutureOr<Either<List<ShortURL>, Failure>> getShortUrls() async {
    return apiGetShortUrls(apiKey, serverUrl, apiVersion);
  }

  /// Gets statistics about the Shlink instance
  FutureOr<Either<ShlinkStats, Failure>> getShlinkStats() async {
    return apiGetShlinkStats(apiKey, serverUrl, apiVersion);
  }

  /// Saves a new short URL to the server
  FutureOr<Either<ShortURL, Failure>> submitShortUrl(
      ShortURLSubmission shortUrl) async {
    return apiSubmitShortUrl(shortUrl, apiKey, serverUrl, apiVersion);
  }

  FutureOr<Either<ShortURL, Failure>> updateShortUrl(
      ShortURLSubmission shortUrl) async {
    return apiUpdateShortUrl(shortUrl, apiKey, serverUrl, apiVersion);
  }

  /// Deletes a short URL from the server, identified by its slug
  FutureOr<Either<String, Failure>> deleteShortUrl(String shortCode) async {
    return apiDeleteShortUrl(shortCode, apiKey, serverUrl, apiVersion);
  }

  /// Gets health data about the server
  FutureOr<Either<ServerHealthResponse, Failure>> getServerHealth() async {
    return apiGetServerHealth(apiKey, serverUrl, apiVersion);
  }

  /// Gets recently created/used short URLs from the server
  FutureOr<Either<List<ShortURL>, Failure>> getRecentShortUrls() async {
    return apiGetRecentShortUrls(apiKey, serverUrl, apiVersion);
  }
}

/// Server response data type about a page of short URLs from the server
class ShortURLPageResponse {
  List<ShortURL> urls;
  int totalPages;

  ShortURLPageResponse(this.urls, this.totalPages);
}

/// Server response data type about the health status of the server
class ServerHealthResponse {
  String status;
  String version;

  ServerHealthResponse({required this.status, required this.version});
}

/// Failure class, used for the API
abstract class Failure {}

/// Used when a request to a server fails
/// (due to networking issues or an unexpected response)
class RequestFailure extends Failure {
  int statusCode;
  String description;

  RequestFailure(this.statusCode, this.description);
}

/// Contains information about an error returned by the Shlink API
class ApiFailure extends Failure {
  String type;
  String detail;
  String title;
  int status;
  List<dynamic>? invalidElements;

  ApiFailure(
      {required this.type,
      required this.detail,
      required this.title,
      required this.status,
      this.invalidElements});
}