using GB5Shared.DTO.Framework.Login;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Logging;
using System.Text.Json;

namespace FrameworkSL.Hubs.DataSync
{
    public class DataSyncHub : Hub<IDataSyncClient>
    {
        private readonly ILogger<DataSyncHub> _logger;

        public DataSyncHub(ILogger<DataSyncHub> logger)
        {
            _logger = logger;
        }

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

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

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

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

        // Client calls this to subscribe to progress for a specific run.
        // Group name: "datasync:{runId}"
        public async Task JoinRunGroup(int runId)
        {
            var group = RunGroup(runId);
            await Groups.AddToGroupAsync(Context.ConnectionId, group);
            _logger.LogInformation("Connection {ConnectionId} joined group {Group}", Context.ConnectionId, group);
        }

        public async Task LeaveRunGroup(int runId)
        {
            var group = RunGroup(runId);
            await Groups.RemoveFromGroupAsync(Context.ConnectionId, group);
        }

        // ── Helpers ───────────────────────────────────────────────────────────

        public static string RunGroup(int runId) => $"datasync:{runId}";

        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 JsonSerializer.Deserialize<LoginDTO>(raw)
                ?? throw new InvalidOperationException("Login header is invalid JSON.");
        }
    }
}