using Microsoft.AspNetCore.SignalR;

namespace RobotNet10.FleetManager.Hubs;

/// <summary>
/// SignalR Hub for real-time robot state and visualization updates.
/// Manages client subscriptions to robot groups for receiving VDA5050 messages.
/// </summary>
/// <remarks>
/// Clients subscribe to specific robots using SubscribeToRobot method.
/// Messages are broadcast to groups named "robot:{robotId}".
/// </remarks>
public class RobotStateHub(
    Services.Logger<RobotStateHub> logger,
    RobotStateHubContext hubContext) : Hub
{
    private readonly Services.Logger<RobotStateHub> _logger = logger;
    private readonly RobotStateHubContext _hubContext = hubContext;

    /// <summary>
    /// Subscribe to receive updates for a specific robot
    /// </summary>
    /// <param name="robotId">Robot identifier (serialNumber)</param>
    public async Task SubscribeToRobot(string robotId)
    {
        var groupName = GetGroupName(robotId);
        await Groups.AddToGroupAsync(Context.ConnectionId, groupName);
    }

    /// <summary>
    /// Unsubscribe from updates for a specific robot
    /// </summary>
    /// <param name="robotId">Robot identifier (serialNumber)</param>
    public async Task UnsubscribeFromRobot(string robotId)
    {
        var groupName = GetGroupName(robotId);
        await Groups.RemoveFromGroupAsync(Context.ConnectionId, groupName);
    }

    private static string GetGroupName(string robotId)
    {
        return $"robot:{robotId}";
    }

    /// <summary>
    /// Subscribe to receive monitor updates for a specific levelId
    /// Each connection can only subscribe to one levelId at a time.
    /// Maximum 5 connections per levelId (FIFO).
    /// </summary>
    /// <param name="levelId">Level identifier (LayoutLevel.Id)</param>
    public async Task SubscribeToLevelForMonitor(Guid levelId)
    {
        var evictedConnectionId = _hubContext.SubscribeToLevel(Context.ConnectionId, levelId);
        
        // If a connection was evicted, notify it
        if (evictedConnectionId != null)
        {
            _logger.Info($"Connection {evictedConnectionId} evicted from level {levelId} (max 5 connections reached)");
            await Clients.Client(evictedConnectionId).SendAsync("OnMonitorDeactivated");
        }
        
        await Task.CompletedTask;
    }

    /// <summary>
    /// Unsubscribe from monitor updates for the current level
    /// </summary>
    public async Task UnsubscribeFromLevelForMonitor()
    {
        var removed = _hubContext.UnsubscribeFromLevel(Context.ConnectionId);
        if (removed)
        {
            _logger.Info($"Client {Context.ConnectionId} unsubscribed from level for monitor");
        }
        await Task.CompletedTask;
    }

    public override async Task OnDisconnectedAsync(Exception? exception)
    {
        // Remove connection from subscription manager
        _hubContext.RemoveConnection(Context.ConnectionId);
        
        if (exception != null)
        {
            _logger.Warning($"Client {Context.ConnectionId} disconnected with error: {exception.Message}");
        }
        await base.OnDisconnectedAsync(exception);
    }
}