using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using CommunityToolkit.Mvvm.Messaging;
using gehGassi.Dto;
using gehGassi.Dto.Messages;
using gehGassiApp.Core.Interfaces;
using gehGassiApp.Core.Interfaces.Synchronization;
using gehGassiApp.Core.Messaging;
using Microsoft.AspNetCore.SignalR.Client;

namespace gehGassiApp.Core.Services
{
    /// <summary>
    /// Service der Daten vom AppHub des Servers empfangen kann
    /// </summary>
    public class AppHubService : IAppHubService
    {
        private string _baseAddress;
        private HubConnection _connection;

        /// <summary>
        /// Erstellt eine Instanz
        /// </summary>
        /// <param name="baseAddress">Basis-Adresse des Servers</param>
        public AppHubService(string baseAddress)
        {
            _baseAddress = baseAddress;
            if (_baseAddress.EndsWith("/"))
                _baseAddress = _baseAddress.Substring(0, _baseAddress.Length - 1);
        }

        /// <summary>
        /// Connection zum Hub erstellen
        /// </summary>
        private void CreateConnection(string accessToken)
        {
            _connection = new HubConnectionBuilder().WithUrl($"{_baseAddress}/appHub", o =>
            {
                o.AccessTokenProvider = () => Task.FromResult(accessToken);
                o.HttpMessageHandlerFactory = (message) =>
                {
#if DEBUG
                    // bypass SSL certificate
                    if (message is HttpClientHandler clientHandler)
                    {
                        clientHandler.ServerCertificateCustomValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;
                    }
#endif
                    return message;
                };
            }).WithAutomaticReconnect().Build();
        }

        /// <summary>
        /// Setzen der Basis-Adresse des Servers
        /// </summary>
        /// <param name="baseAddress">Basis-Adresse</param>
        public async Task SetBaseAddressAsync(string baseAddress)
        {
            _baseAddress = baseAddress;
            if (_baseAddress.EndsWith("/"))
                _baseAddress = _baseAddress.Substring(0, _baseAddress.Length - 1);

            await DisconnectAsync();
        }

        public async Task ConnectAsync(string accessToken)
        {
            if (_connection != null && _connection.State == HubConnectionState.Connected) return;
            if (_connection != null && _connection.State == HubConnectionState.Connecting) return;
            if (_connection != null && _connection.State == HubConnectionState.Reconnecting) return;

            //Buchen der Nachrichten
            CreateConnection(accessToken);

            _connection.On("AppUserChanged", async () => await AppUserChangedAsync());
            _connection.On("NewsCategoriesChanged", async () => await NewsCategoriesChangedAsync());
            _connection.On("ConversationMessageAdded", async (MessageDto messageDto) => await ConversationMessageAddedAsync(messageDto));
            _connection.On("MessageAdded", async () => await MessageAddedAsync());
            _connection.On("SystemMessageAdded", async () => await SystemMessageAddedAsync());
            _connection.On("Logout", async () => await LogoutAsync());

            try
            {
                
                await _connection.StartAsync().ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
        }

        /// <summary>
        /// Verbindung trennen
        /// </summary>
        /// <returns>Task</returns>
        public async Task DisconnectAsync()
        {
            if (_connection != null)
            {
                try
                {
                    await _connection.StopAsync();
                    await _connection.DisposeAsync();
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine(ex.Message);
                }
            }

            //CreateConnection();
        }

        /// <summary>
        /// Gibt zurück ob eine SignalR Verbindung besteht
        /// </summary>
        /// <returns>true wenn ja oder reconnecting, false sonst</returns>
        public bool IsConnected()
        {
            if (_connection == null)
                return false;
            return _connection.State != HubConnectionState.Disconnected;
        }

        /// <summary>
        /// Buchen der Events eines App-Users
        /// </summary>
        /// <param name="appUserId">Id des AppUsers</param>
        /// <returns>Task</returns>
        public async Task JoinAppUserAsync(string appUserId)
        {
            if(_connection == null || string.IsNullOrWhiteSpace(appUserId))
                return;

            if (_connection is { State: HubConnectionState.Connected })
            {
                await _connection.SendAsync("JoinAppUser", appUserId);
            }
        }

        /// <summary>
        /// Abbestellen der Events eines App-Users
        /// </summary>
        /// <param name="appUserId">Id des AppUsers</param>
        /// <returns>Task</returns>
        public async Task LeaveAppUserAsync(string appUserId)
        {
            if (_connection == null || string.IsNullOrWhiteSpace(appUserId))
                return;

            if (_connection is { State: HubConnectionState.Connected })
            {
                await _connection.SendAsync("LeaveAppUser", appUserId);
            }
        }

        /// <summary>
        /// Buchen der Events einer Konversation
        /// </summary>
        /// <param name="conversationId">Id der Konversation</param>
        /// <param name="appUserId">Id des AppUsers</param>
        /// <returns>Task</returns>
        public async Task JoinConversationAsync(string conversationId, string appUserId)
        {
            if (_connection == null || string.IsNullOrWhiteSpace(appUserId) || string.IsNullOrWhiteSpace(conversationId))
                return;

            if (_connection is { State: HubConnectionState.Connected })
            {
                await _connection.SendAsync("JoinConversation", conversationId, appUserId);
            }
        }

        /// <summary>
        /// Abbestellen der Events einer Konversation
        /// </summary>
        /// <param name="conversationId">Id der Konversation</param>
        /// <param name="appUserId">Id des AppUsers</param>
        /// <returns>Task</returns>
        public async Task LeaveConversationAsync(string conversationId, string appUserId)
        {
            if (_connection == null || string.IsNullOrWhiteSpace(appUserId) || string.IsNullOrWhiteSpace(conversationId))
                return;

            if (_connection is { State: HubConnectionState.Connected })
            {
                await _connection.SendAsync("LeaveConversation", conversationId, appUserId);
            }
        }

        #region EventHandler

        /// <summary>
        /// Handler wenn sich der App-User geändert hat
        /// </summary>
        /// <returns>Task</returns>
        private async Task AppUserChangedAsync()
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new SignalRAppUserChangedMessage());
        }

        /// <summary>
        /// Handler wenn sich News-Kategorien geändert haben
        /// </summary>
        /// <returns>Task</returns>
        private async Task NewsCategoriesChangedAsync()
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new SignalRNewsCategoriesChangedMessage());
        }

        /// <summary>
        /// Handler wenn zu einer Konversation eine Nachricht hinzugefügt wurde
        /// </summary>
        /// <param name="message"></param>
        /// <returns></returns>
        private async Task ConversationMessageAddedAsync(MessageDto message)
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new SignalRConversationMessageAddedMessage(message.ConversationId));
        }

        /// <summary>
        /// Handler wenn neue Nachrichten für einen Benutzer da sind
        /// </summary>
        /// <returns>Task</returns>
        private async Task MessageAddedAsync()
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new MessagesChangedMessage());
        }

        /// <summary>
        /// Handler wenn neue SystemNachrichten für einen Benutzer da sind
        /// </summary>
        /// <returns>Task</returns>
        private async Task SystemMessageAddedAsync()
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new SignalRSystemMessagesChangedMessage());
        }

        /// <summary>
        /// Handler wenn der Benutzer abgemeldet werden soll
        /// </summary>
        /// <returns>Task</returns>
        private async Task LogoutAsync()
        {
            await Task.Delay(1);
            WeakReferenceMessenger.Default.Send(new LogoutMessage());
        }

        #endregion
    }
}