using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.SignalR.Client;
using RobotApp.Common.Shares;
using RobotApp.VDA5050.State;
using System.Collections.Concurrent;
using System.Text.Json;

namespace RobotApp.Client.Services;

// ================= CONNECTION STATE =================
public enum RobotClientState
{
    Disconnected,
    Connecting,
    Connected,
    Reconnecting
}

// ================= CLIENT =================
public sealed class RobotStateClient : IAsyncDisposable
{
    private readonly NavigationManager _nav;
    private HubConnection? _connection;

    private readonly object _lock = new();
    private bool _started;

    public ConcurrentDictionary<string, StateMsg> LatestStates { get; } = new();

    // ================= EVENTS =================
    public event Action<string, StateMsg>? OnStateReceived;
    public event Action<StateMsg>? OnStateReceivedAny;
    public event Action<RobotClientState>? OnConnectionStateChanged;

    public RobotClientState ConnectionState { get; private set; } = RobotClientState.Disconnected;

    // ================= CTOR =================
    public RobotStateClient(NavigationManager nav)
    {
        _nav = nav;
    }

    // ================= STATE HELPER =================
    private void SetState(RobotClientState state)
    {
        if (ConnectionState == state) return;

        ConnectionState = state;
        OnConnectionStateChanged?.Invoke(state);
    }

    // ================= START =================
    public async Task StartAsync(string hubPath = "/hubs/robot")
    {
        lock (_lock)
        {
            if (_started) return;
            _started = true;
        }

        SetState(RobotClientState.Connecting);

        _connection = new HubConnectionBuilder()
            .WithUrl(_nav.ToAbsoluteUri(hubPath))
            .WithAutomaticReconnect(new[]
            {
                TimeSpan.Zero,
                TimeSpan.FromSeconds(2),
                TimeSpan.FromSeconds(10)
            })
            .Build();

        _connection.Reconnecting += _ =>
        {
            SetState(RobotClientState.Reconnecting);
            return Task.CompletedTask;
        };

        _connection.Reconnected += _ =>
        {
            SetState(RobotClientState.Connected);
            return Task.CompletedTask;
        };

        _connection.Closed += async error =>
        {
            _started = false;

            if (_connection != null)
            {
                try
                {
                    await StartAsync(hubPath);
                }
                catch { }
            }
        };

        _connection.On<string>("ReceiveState", HandleState);

        try
        {
            await _connection.StartAsync();
            SetState(RobotClientState.Connected);
        }
        catch
        {
            _started = false;
            SetState(RobotClientState.Disconnected);
        }
    }

    // ================= HANDLE STATE =================
    private void HandleState(string stateJson)
    {
        StateMsg? state;

        try
        {
            state = JsonSerializer.Deserialize<StateMsg>(
                stateJson,
                JsonOptionExtends.Read
            );
        }
        catch
        {
            return;
        }

        if (state?.SerialNumber == null)
            return;

        LatestStates[state.SerialNumber] = state;

        OnStateReceived?.Invoke(state.SerialNumber, state);
        OnStateReceivedAny?.Invoke(state);
    }

    // ================= SUBSCRIBE =================
    public async Task SubscribeRobotAsync(string serialNumber)
    {
        if (_connection?.State != HubConnectionState.Connected)
            return;

        try
        {
            await _connection.InvokeAsync("JoinRobot", serialNumber);
        }
        catch
        {
            // ignore – reconnect sẽ tự join lại
        }
    }

    public async Task UnsubscribeRobotAsync(string serialNumber)
    {
        if (_connection?.State == HubConnectionState.Connected)
        {
            try
            {
                await _connection.InvokeAsync("LeaveRobot", serialNumber);
            }
            catch { }
        }

        LatestStates.TryRemove(serialNumber, out _);
    }

    // ================= GET CACHE =================
    public StateMsg? GetLatestState(string serialNumber)
    {
        LatestStates.TryGetValue(serialNumber, out var state);
        return state;
    }

    // ================= DISPOSE =================
    public async ValueTask DisposeAsync()
    {
        _started = false;
        SetState(RobotClientState.Disconnected);

        if (_connection != null)
        {
            await _connection.DisposeAsync();
            _connection = null;
        }
    }
}