using FLSBLL.Instance;
using GB5Shared.DTO.Framework.Login;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Logging;

namespace FLSSL.Hubs;

public class FlsMonitorHub(
    IFlsInstanceBLL          _instanceBll,
    ILogger<FlsMonitorHub>   _logger
) : Hub<IFlsMonitorClient>
{
    // ── Group naming: fls:instance:{flsInstanceId} ────────────────
    private static string InstanceGroup(int flsInstanceId) => $"fls:instance:{flsInstanceId}";

    // ── Connection lifecycle ──────────────────────────────────────

    public override async Task OnConnectedAsync()
    {
        _logger.LogInformation("FlsMonitorHub connected: {ConnectionId}", Context.ConnectionId);
        await base.OnConnectedAsync();
    }

    public override async Task OnDisconnectedAsync(Exception? exception)
    {
        if (exception is not null)
            _logger.LogWarning(exception, "FlsMonitorHub disconnected with error: {ConnectionId}",
                Context.ConnectionId);
        await base.OnDisconnectedAsync(exception);
    }

    // ── Hub methods ───────────────────────────────────────────────

    /// <summary>
    /// Incharge joins the monitor group for a specific instance to receive live updates.
    /// </summary>
    public async Task JoinInstanceMonitor(int flsInstanceId)
    {
        var login = GetLoginDTO();
        try
        {
            await Groups.AddToGroupAsync(Context.ConnectionId, InstanceGroup(flsInstanceId));
            _logger.LogInformation("User {UserId} joined FLS monitor for instance {InstanceId}",
                login.UserId, flsInstanceId);

            // Push current summary immediately on join
            var summaryJson = await _instanceBll.GetSummaryAsync(flsInstanceId, login, CancellationToken.None)
                .ConfigureAwait(false);
            await Clients.Caller.ReceiveError(string.Empty);  // ping to confirm connection
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "JoinInstanceMonitor failed for instance {Id}", flsInstanceId);
            await Clients.Caller.ReceiveError("JOIN_FAILED");
        }
    }

    /// <summary>
    /// Incharge leaves the monitor group for a specific instance.
    /// </summary>
    public async Task LeaveInstanceMonitor(int flsInstanceId)
    {
        await Groups.RemoveFromGroupAsync(Context.ConnectionId, InstanceGroup(flsInstanceId));
        _logger.LogInformation("Connection {ConnectionId} left FLS monitor for instance {InstanceId}",
            Context.ConnectionId, flsInstanceId);
    }

    // ── Helper ────────────────────────────────────────────────────

    private LoginDTO GetLoginDTO()
    {
        var http = Context.GetHttpContext()
            ?? throw new InvalidOperationException("Hub invoked outside HTTP context.");
        var raw = http.Request.Headers["Login"].FirstOrDefault()
            ?? throw new InvalidOperationException("Login header missing.");
        return System.Text.Json.JsonSerializer.Deserialize<LoginDTO>(raw)
            ?? throw new InvalidOperationException("Login header is invalid JSON.");
    }
}