using System.Collections.ObjectModel;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using Massenger.Client.Pages;
using Massenger.Client.Services;
using Massenger.Shared;

namespace Massenger.Client.ViewModels;

public partial class ChatsViewModel(ApiClient apiClient, RealtimeService realtimeService) : BaseViewModel
{
    public ObservableCollection<ChatSummaryDto> Chats { get; } = [];

    [ObservableProperty]
    private ChatSummaryDto? selectedChat;

    public string EmptyState => Chats.Count == 0 ? "No chats yet. Open Discover to start a dialog, group or channel." : string.Empty;

    [RelayCommand]
    public async Task LoadAsync()
    {
        await RunBusyAsync(async () =>
        {
            var chats = await apiClient.GetChatsAsync();
            MainThread.BeginInvokeOnMainThread(() =>
            {
                Chats.Clear();
                foreach (var chat in chats)
                {
                    Chats.Add(chat);
                }

                OnPropertyChanged(nameof(EmptyState));
            });
        });
    }

    [RelayCommand]
    public async Task OpenChatAsync(ChatSummaryDto? chat)
    {
        if (chat is null)
        {
            return;
        }

        SelectedChat = null;
        await Shell.Current.GoToAsync($"{nameof(ChatPage)}?chatId={chat.Id}");
    }

    public void AttachRealtime()
    {
        realtimeService.MessageReceived -= OnRealtimeChanged;
        realtimeService.MessageUpdated -= OnRealtimeChanged;
        realtimeService.ChatCreated -= OnChatCreated;
        realtimeService.ChatsChanged -= OnRealtimeChanged;

        realtimeService.MessageReceived += OnRealtimeChanged;
        realtimeService.MessageUpdated += OnRealtimeChanged;
        realtimeService.ChatCreated += OnChatCreated;
        realtimeService.ChatsChanged += OnRealtimeChanged;
    }

    private void OnChatCreated(object? sender, ChatSummaryDto e)
    {
        MainThread.BeginInvokeOnMainThread(() => _ = LoadAsync());
    }

    private void OnRealtimeChanged(object? sender, EventArgs e)
    {
        MainThread.BeginInvokeOnMainThread(() => _ = LoadAsync());
    }

    private void OnRealtimeChanged(object? sender, MessageDto e)
    {
        MainThread.BeginInvokeOnMainThread(() => _ = LoadAsync());
    }
}