using System;
using System.Collections.ObjectModel;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Threading;
using System.Linq;
using Xamarin.Forms;
using Aurora.Proto.Party;
using Aurora.Models.Media;
using Aurora.Services.Client;
using Aurora.Design.Views.Party.NewPartyDialog;
using Aurora.Services.Settings;
using Aurora.Services.Server;
using Aurora.Services.EventManager;
using Grpc.Core;

namespace Aurora.Design.Views.Party
{
    //TODO refactor
    enum PartyState
    {
        SelectingHost,
        InParty,
        Hosting,
        Connecting,
    }
    delegate void EventHandler(BaseEvent e);
    public class PartyViewModel : BaseViewModel
    {
        private PartyState _state;
        private string _hostname = "";
        private ObservableCollection<Member> _members;
        private ObservableCollection<BaseMedia> _queue;
        private BaseMedia _selectedMedia;
        private ISettingsService _settingsService;
        private IClientService _clientService;
        private IServerService _serverService;
        private IEventManager _eventManager;

        private CancellationTokenSource _eventCancellationTokenSource;

        private Dictionary<BaseEvent.DerivedEventOneofCase, EventHandler> _eventHandlers;

        private int _selectedTabIndex;

        public PartyViewModel(
            ISettingsService settingsService,
            IServerService serverService,
            IEventManager eventManager,
            IClientService clientService)
        {
            _members = new ObservableCollection<Member>();
            _queue = new ObservableCollection<BaseMedia>();

            this._settingsService = settingsService;
            this._serverService = serverService;
            this._eventManager = eventManager;
            this._clientService = clientService;

            SetState(PartyState.SelectingHost);

            PlayCommand = new Command(OnDoubleClickCommandExecute, CanDoubleClickCommandExecute);

            LeavePartyCommand = new Command(OnLeavePartyCommandExecute, CanLeavePartyCommandExecute);

            //Setup event handlers
            _eventHandlers = new Dictionary<BaseEvent.DerivedEventOneofCase, EventHandler>()
            {
                {BaseEvent.DerivedEventOneofCase.MediaPausedEvent, this.OnRemoteMediaPaused},
                {BaseEvent.DerivedEventOneofCase.MediaResumedEvent, this.OnRemoteMediaResumed},
                {BaseEvent.DerivedEventOneofCase.NewMediaPlayingEvent, this.OnNewRemoteMediaPlaying},
                {BaseEvent.DerivedEventOneofCase.MemberCreatedEvent, this.OnPartyMemberJoined},
                {BaseEvent.DerivedEventOneofCase.MemberDeletedEvent, this.OnPartyMemberLeft}
            };
        }

        #region Properties

        public int SelectedTabIndex
        {
            get { return _selectedTabIndex; }
            set { SetProperty(ref _selectedTabIndex, value); }
        }

        /// <summary>
        /// Publc property for the members list
        /// </summary>
        /// <value></value>
        public ObservableCollection<Member> Members
        {
            get
            {
                return _members;
            }
            set
            {
                SetProperty(ref _members, value);
            }
        }

        /// <summary>
        /// Public property for queue item source
        /// </summary>
        /// <value></value>
        public ObservableCollection<BaseMedia> Queue
        {
            get
            {
                return _queue;
            }
            set
            {
                if (value != _queue)
                {
                    SetProperty(ref _queue, value);
                }
            }
        }

        /// <summary>
        /// Public property for the currently selected song.
        /// </summary>
        /// <value></value>
        public BaseMedia SelectedSong
        {
            get { return _selectedMedia; }
            set { SetProperty(ref _selectedMedia, value); }
        }

        /// <summary>
        /// Public property for playing media
        /// </summary>
        /// <value></value>
        public Command PlayCommand { get; private set; }

        public Command LeavePartyCommand { get; private set; }

        #endregion Properties

        #region Events
        /// <summary>
        /// Called by framework when view becomes active
        /// </summary>
        /// <returns></returns>
        public override async Task OnActive()
        {
            OnPropertyChanged("SelectedTabIndex");
            if (this._state == PartyState.Hosting ||
                this._state == PartyState.InParty)
            {
                await this.GetEvents().ConfigureAwait(false);
            }
            else
            {
                //Open host selection modal
                NewPartyDialogViewModel vm = new NewPartyDialogViewModel();
                ConnectionDetails details = new ConnectionDetails();
                vm.Finish = () =>
                {
                    this.HideModal();
                    details = vm.ReturnObject as ConnectionDetails;
                    _hostname = details.HostName;
                    switch (details.ConnectionType)
                    {
                        case ConnectionType.Host:
                            {
                                OnHostCommandExecute();
                                break;
                            }
                        case ConnectionType.Join:
                            {
                                OnJoinCommandExecute();
                                break;
                            }
                    }
                };

                this.ShowModal(typeof(NewPartyDialog.NewPartyDialog), vm);
            }
        }

        /// <summary>
        /// Called by framework when view becomes inactive
        /// </summary>
        /// <returns></returns>
        public override Task OnInactive()
        {
            if(this._eventCancellationTokenSource != null){
                this._eventCancellationTokenSource.Cancel();
            }
            
            return Task.FromResult<object>(null);
        }

        /// <summary>
        /// Remote media paused event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        public void OnRemoteMediaPaused(BaseEvent e)
        {
            StopPlaying();
        }

        /// <summary>
        /// Remote playing new media event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        public void OnNewRemoteMediaPlaying(BaseEvent e)
        {
            PlayFromBeginning(GetMediaFromQueue(e.NewMediaPlayingEvent.Media.Name));
        }

        /// <summary>
        /// Remote resumed playing event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        public void OnRemoteMediaResumed(BaseEvent e)
        {
            PlayResume();
        }

        /// <summary>
        /// Member joined party event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        public void OnPartyMemberJoined(BaseEvent e)
        {
            Members.Add(e.MemberCreatedEvent.Member);
        }

        /// <summary>
        /// Member left party event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="args"></param>
        public void OnPartyMemberLeft(BaseEvent e)
        {
            var found = Members.Where(x => x.Name == e.MemberDeletedEvent.MemberName);
            foreach (Member member in found)
            {
                _members.Remove(member);
            }
        }

        #endregion Events

        #region Commands
        private async void OnJoinCommandExecute()
        {
            SetState(PartyState.Connecting);
            _clientService.Start(_hostname, this._settingsService.DefaultPort.ToString());
            await JoinParty(false);

            //TODO add cancellation token
            try
            {
                SetState(PartyState.InParty);
                await GetEvents().ConfigureAwait(true);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception occurred while receiviing events: ", ex.Message);
            }
        }

        private bool CanJoinCommandExecute()
        {
            return true;
        }

        private async void OnHostCommandExecute()
        {
            //Change state
            SetState(PartyState.Connecting);
            _serverService.Start("test", "asdf");
            string localHost = ServerService.GetLocalIPAddress();
            _clientService.Start(localHost, this._settingsService.DefaultPort.ToString());
            await JoinParty(true);


            //TODO add cancellation token
            try
            {
                SetState(PartyState.Hosting);
                await GetEvents().ConfigureAwait(false);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception occurred while receiviing events: ", ex.Message);
            }
        }

        private bool CanHostCommandExecute()
        {
            return true;
        }

        private async void OnLeavePartyCommandExecute()
        {
            await _clientService.RemotePartyServiceClient.DeleteMemberAsync(new DeleteMemberRequest()
            {
                Name = _settingsService.ClientName
            });
        }

        private bool CanLeavePartyCommandExecute()
        {
            return (this._state == PartyState.InParty || this._state == PartyState.Hosting) ? true : false;
        }

        public override void OnPlayButtonCommandExecute()
        {
            if (base.IsPlaying())
            {
                //Fire play stopped event
                AudioMetadata meta = _selectedMedia.Metadata as AudioMetadata;
                MediaPausedEvent mediaPaused = new MediaPausedEvent();

                _eventManager.FireEvent(new BaseEvent()
                {
                    MediaPausedEvent = mediaPaused
                });
            }
            else
            {
                //Fire play resume event
                AudioMetadata meta = _selectedMedia.Metadata as AudioMetadata;
                MediaResumedEvent mediaResumed = new MediaResumedEvent();

                _eventManager.FireEvent(new BaseEvent()
                {
                    MediaResumedEvent = mediaResumed
                });
            }
        }

        public override bool CanPlayButtonCommandExecute()
        {
            return this._state == PartyState.Hosting;
        }

        public override bool CanNextButtonCommandExecute()
        {
            return this._state == PartyState.Hosting;
        }

        public override bool CanPreviousButtonCommandExecute()
        {
            return this._state == PartyState.Hosting;
        }

        /// <summary>
        /// On double click execute, fire media playing event
        /// </summary>
        public void OnDoubleClickCommandExecute()
        {
            //Fire Playing event
            AudioMetadata meta = _selectedMedia.Metadata as AudioMetadata;
            NewMediaPlayingEvent mediaPlaying = new NewMediaPlayingEvent()
            {
                Media = new Media()
                {
                    //TODO need full resource name
                    Name = _selectedMedia.Id,
                    Title = meta.Title,
                    Artist = meta.Artist,
                    Album = meta.Album,
                }
            };

            _eventManager.FireEvent(new BaseEvent()
            {
                NewMediaPlayingEvent = mediaPlaying
            });
        }

        public bool CanDoubleClickCommandExecute()
        {
            return this._state == PartyState.Hosting;
        }


        #endregion Commands

        #region Private Methods
        /// <summary>
        /// Join the remote party.
        /// </summary>
        /// <returns></returns>
        private async Task JoinParty(bool asHost)
        {
            try
            {
                Member resp = await _clientService.RemotePartyServiceClient.CreateMemberAsync(new CreateMemberRequest
                {
                    Member = new Member()
                    {
                        UserName = this._settingsService.Username,
                    }
                });

                this._settingsService.ClientName = resp.Name;

                await RefreshMembers();

                //Subscribe to events
                await SubscribeToEvents();

                Queue.Clear();

                ListMediaResponse mediaResponse = await _clientService.RemotePartyServiceClient.ListMediaAsync(new ListMediaRequest()
                {
                    PageSize = 50,
                    Parent = "TODO"
                });

                //Convert received data to remote audio models
                foreach (Media data in mediaResponse.Media)
                {
                    //Assign received metadata (since this can't be aquired from a file)
                    AudioMetadata meta = new AudioMetadata();
                    meta.Title = data.Title;
                    meta.Album = data.Album;
                    meta.Artist = data.Artist;
                    meta.Duration = data.Duration;

                    RemoteAudio remote = new RemoteAudio(data.Name,
                        asHost,
                        meta,
                        _clientService.RemotePartyServiceClient);

                    Queue.Add(remote);
                    OnPropertyChanged("Queue");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Error subscribing to events: " + ex.Message);
            }
        }

        private async Task LeaveParty()
        {
            //Stop receiving events
            // _client.StopEvents();

            //Unsubscribe
            await UnsubscribeFromEvents();

            //Leave party
            DeleteMemberRequest req = new DeleteMemberRequest()
            {
                Name = _settingsService.ClientName
            };

            await _clientService.RemotePartyServiceClient.DeleteMemberAsync(req);
        }

        private async Task SubscribeToEvents()
        {
            CreateEventSubscriptionListRequest req = new CreateEventSubscriptionListRequest();
            req.Parent = this._settingsService.ClientName;
            req.EventSubscriptions.Add(new EventSubscription() { Type = EventType.MemberCreated });
            req.EventSubscriptions.Add(new EventSubscription() { Type = EventType.MemberDeleted });
            req.EventSubscriptions.Add(new EventSubscription() { Type = EventType.MediaPlaying });
            req.EventSubscriptions.Add(new EventSubscription() { Type = EventType.MediaStopped });

            Console.WriteLine(string.Format("CLIENT {0} - SubscribeToEvents called from client with id", this._settingsService.ClientName));
            await _clientService.RemotePartyServiceClient.CreateEventSubscriptionListAsync(req);
        }
        private async Task UnsubscribeFromEvents()
        {
            DeleteAllEventSubscriptionsRequest unsubscribeReq = new DeleteAllEventSubscriptionsRequest();
            await _clientService.RemotePartyServiceClient.DeleteAllEventSubscriptionsAsync(unsubscribeReq);
        }

        /// <summary>
        /// Refresh members list.
        /// </summary>
        private async Task RefreshMembers()
        {
            Members.Clear();
            ListMembersResponse response = await _clientService.RemotePartyServiceClient.ListMembersAsync(
                new ListMembersRequest()
                {
                    Parent = "TODO",
                    PageSize = 50,
                });
            //Add members
            foreach (Member member in response.Members)
            {
                Members.Add(member);
            }
        }

        private void SetState(PartyState state)
        {
            _state = state;
            OnPropertyChanged("IsSelectingHost");
            OnPropertyChanged("IsNotSelectingHost");
        }

        private BaseMedia GetMediaFromQueue(string Id)
        {
            if (_queue.Any((BaseMedia media) => media.Id == Id))
            {
                BaseMedia media = _queue.First((BaseMedia med) => med.Id == Id);
                return media;
            }
            else
            {
                return null;
            }
        }
        private void PlayFromBeginning(BaseMedia args)
        {
            base.ChangePlayerState(args, Main.PlayAction.Play);
        }

        private void PlayResume()
        {
            base.ChangePlayerState(null, Main.PlayAction.Resume);
        }

        private void StopPlaying()
        {
            base.ChangePlayerState(null, Main.PlayAction.Pause);
        }

        /// <summary>
        /// Asynchronous function for processing events off of the event stream.
        /// </summary>
        /// <returns></returns>
        public async Task GetEvents()
        {
            _eventCancellationTokenSource = new CancellationTokenSource();
            string clientName = this._settingsService.ClientName;
            Console.WriteLine(string.Format("CLIENT {0} - GetEvents called from client with id", clientName));
            using (AsyncServerStreamingCall<BaseEvent> eventStream = _clientService.RemotePartyServiceClient
                .GetEvents(new GetEventsRequest { Parent = this._settingsService.ClientName }))
            {
                try
                {
                    while (!_eventCancellationTokenSource.Token.IsCancellationRequested &&
                        await eventStream.ResponseStream.MoveNext(_eventCancellationTokenSource.Token))
                    {
                        try
                        {
                            BaseEvent e = new BaseEvent(eventStream.ResponseStream.Current);

                            _eventHandlers.TryGetValue(e.DerivedEventCase, out EventHandler handler);

                            if (handler != null && handler != null)
                            {
                                handler.Invoke(e);
                            }
                        }
                        catch (Exception ex)
                        {
                            Console.WriteLine("Exception while parsing event ---" + ex.Message);
                        }

                    }
                }
                catch (Exception ex)
                {
                    Console.WriteLine(string.Format("EXCEPTION while parsing events --- " + ex.Message));
                }
            }
        }
        #endregion Private Methods
    }
}