using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Logging;
using System;
using System.Threading.Tasks;
using Timeline.Auth;
using Timeline.Services;
using Timeline.Services.Timeline;
using Timeline.Services.User;

namespace Timeline.SignalRHub
{
    public class TimelineHub : Hub<ITimelineClient>
    {
        private readonly ILogger<TimelineHub> _logger;
        private readonly ITimelineService _timelineService;

        public TimelineHub(ILogger<TimelineHub> logger, ITimelineService timelineService)
        {
            _logger = logger;
            _timelineService = timelineService;
        }

        public static string GenerateTimelinePostChangeListeningGroupName(string timelineName)
        {
            return $"timeline-post-change-{timelineName}";
        }

        public async Task SubscribeTimelinePostChange(string timelineName)
        {
            try
            {
                var timelineId = await _timelineService.GetTimelineIdByNameAsync(timelineName);
                var user = Context.User;
                if (!user.HasPermission(UserPermission.AllTimelineManagement) && !await _timelineService.HasReadPermissionAsync(timelineId, user.GetOptionalUserId()))
                    throw new HubException("Forbidden.");

                var group = GenerateTimelinePostChangeListeningGroupName(timelineName);
                await Groups.AddToGroupAsync(Context.ConnectionId, group);
                _logger.LogInformation("Add connection {0} to group {1}", Context.ConnectionId, group);
            }
            catch (ArgumentException)
            {
                throw new HubException("Timeline name is illegal.");
            }
            catch (EntityNotExistException)
            {
                throw new HubException("Timeline not exist.");
            }
        }

        public async Task UnsubscribeTimelinePostChange(string timelineName)
        {
            var group = GenerateTimelinePostChangeListeningGroupName(timelineName);
            await Groups.RemoveFromGroupAsync(Context.ConnectionId, group);
            _logger.LogInformation("Remove connection {0} from group {1}", Context.ConnectionId, group);
        }
    }
}