using MediatR;
using Microsoft.AspNetCore.SignalR;
using Knot.Modules.Chats.Domain;
using Knot.Modules.Chats.Infrastructure.SignalR;
using Knot.Shared.Kernel;

namespace Knot.Modules.Chats.Infrastructure.Handlers;

/// <summary>
/// Обработчик доменного события отправки сообщения.
/// Отправляет уведомление через SignalR всем участникам чата.
/// </summary>
public sealed class MessageSentDomainEventHandler : INotificationHandler<MessageSentDomainEvent>
{
    private readonly IHubContext<ChatHub> _hubContext;
    private readonly IMessageRepository _messageRepository;
    private readonly IUserDisplayNameProvider _displayNameProvider;

    public MessageSentDomainEventHandler(
        IHubContext<ChatHub> hubContext,
        IMessageRepository messageRepository,
        IUserDisplayNameProvider displayNameProvider)
    {
        _hubContext = hubContext;
        _messageRepository = messageRepository;
        _displayNameProvider = displayNameProvider;
    }

    public async Task Handle(MessageSentDomainEvent notification, CancellationToken cancellationToken)
    {
        var message = await _messageRepository.GetByIdAsync(notification.MessageId, cancellationToken);
        if (message is null)
        {
            return;
        }

        var userInfo = await _displayNameProvider.GetUserInfoAsync(message.SenderId, cancellationToken);
        var senderObj = userInfo != null
            ? new { Id = userInfo.Id, Username = userInfo.Username, DisplayName = userInfo.DisplayName, Avatar = userInfo.Avatar }
            : new { Id = message.SenderId, Username = "unknown", DisplayName = "Unknown", Avatar = (string?)null };

        // Fetch forwarded from info if exists
        object? forwardedFromObj = null;
        if (message.ForwardedFromId.HasValue)
        {
            var fwdUserInfo = await _displayNameProvider.GetUserInfoAsync(message.ForwardedFromId.Value, cancellationToken);
            forwardedFromObj = fwdUserInfo != null
                ? new { Id = fwdUserInfo.Id, Username = fwdUserInfo.Username, DisplayName = fwdUserInfo.DisplayName, Avatar = fwdUserInfo.Avatar }
                : new { Id = message.ForwardedFromId.Value, Username = "unknown", DisplayName = "Unknown", Avatar = (string?)null };
        }

        // Fetch reply info if exists
        object? replyToObj = null;
        if (message.ReplyToId.HasValue)
        {
            var replyMsg = await _messageRepository.GetByIdAsync(message.ReplyToId.Value, cancellationToken);
            if (replyMsg != null)
            {
                var replySenderInfo = await _displayNameProvider.GetUserInfoAsync(replyMsg.SenderId, cancellationToken);
                replyToObj = new
                {
                    Id = replyMsg.Id,
                    Content = replyMsg.Content,
                    Quote = message.Quote,
                    media = replyMsg.Media.Select(rm => new { rm.Id, rm.Type, rm.Url }).ToList(),
                    Sender = replySenderInfo != null
                        ? new { Id = replySenderInfo.Id, Username = replySenderInfo.Username, DisplayName = replySenderInfo.DisplayName }
                        : new { Id = replyMsg.SenderId, Username = "unknown", DisplayName = "Unknown" }
                };
            }
        }

        // Отправляем сообщение в "комнату" чата.
        await _hubContext.Clients.Group(notification.ChatId.ToString())
            .SendAsync("new_message", new
            {
                id = message.Id,
                chatId = message.ChatId,
                senderId = message.SenderId,
                content = message.Content,
                type = message.Type,
                createdAt = message.CreatedAt,
                forwardedFromId = message.ForwardedFromId,
                forwardedFrom = forwardedFromObj,
                replyToId = message.ReplyToId,
                replyTo = replyToObj,
                quote = message.Quote,
                media = message.Media.Select(m => new
                {
                    id = m.Id,
                    type = m.Type,
                    url = m.Url,
                    filename = m.Filename,
                    size = m.Size
                }).ToList(),
                sender = senderObj,
                readBy = new List<object>(),
                storyId = message.StoryId,
                storyMediaUrl = message.StoryMediaUrl,
                storyMediaType = message.StoryMediaType
            }, cancellationToken);
    }
}