using Microsoft.AspNetCore.SignalR;
using NexusReader.Application.Abstractions.Messaging;
using NexusReader.Infrastructure.RealTime;

namespace NexusReader.Infrastructure.RealTime;

/// <summary>
/// SignalR implementation of <see cref="ISyncBroadcaster"/>.
/// Uses <see cref="IHubContext{SyncHub}"/> to push progress updates to all of a user's connected devices.
/// </summary>
internal sealed class SignalRSyncBroadcaster : ISyncBroadcaster
{
    private readonly IHubContext<SyncHub> _hubContext;

    public SignalRSyncBroadcaster(IHubContext<SyncHub> hubContext)
    {
        _hubContext = hubContext;
    }

    /// <inheritdoc />
    public async Task BroadcastProgressAsync(
        string userId,
        string pageId,
        DateTime timestamp,
        string? excludedConnectionId,
        CancellationToken cancellationToken = default)
    {
        var groupName = $"User_{userId}";

        if (!string.IsNullOrEmpty(excludedConnectionId))
        {
            await _hubContext.Clients
                .GroupExcept(groupName, excludedConnectionId)
                .SendAsync("ProgressUpdated", pageId, timestamp, cancellationToken: cancellationToken);
        }
        else
        {
            await _hubContext.Clients
                .Group(groupName)
                .SendAsync("ProgressUpdated", pageId, timestamp, cancellationToken: cancellationToken);
        }
    }
}