using AutoMapper;
using IM_API.Application.Interfaces;
using IM_API.Domain.Events;
using IM_API.Dtos;
using IM_API.Exceptions;
using IM_API.Interface.Services;
using IM_API.Models;
using IM_API.Services;
using IM_API.Tools;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;

namespace IM_API.Application.EventHandlers
{
    public class ConversationEventHandler : IEventHandler<MessageCreatedEvent>
    {
        private readonly IConversationService _conversationService;
        private readonly ILogger<ConversationEventHandler> _logger;
        private readonly ImContext _context;
        private readonly IMapper _mapper;
        public ConversationEventHandler(
            IConversationService conversationService,
            ILogger<ConversationEventHandler> logger,
            ImContext imContext,
            IMapper mapper
            )
        {
            _conversationService = conversationService;
            _logger = logger;
            _context = imContext;
            _mapper = mapper;
        }

        /*
         * 此方法有并发问题，当双方同时第一次发送消息时，
         * 会出现同时创建的情况，其中一方会报错，
         * 导致也未走到更新逻辑，会话丢失
         */
        public async Task Handle(MessageCreatedEvent @event)
        {
            //此处仅处理私聊会话创建
            if (@event.ChatType == ChatType.GROUP)
            {
                return;
            }
            var conversation = await _context.Conversations.FirstOrDefaultAsync(
                   x => x.UserId == @event.MsgSenderId && x.TargetId == @event.MsgRecipientId
                );
            //如果首次发消息则创建双方会话
            if (conversation is null)
            {
                Conversation senderCon = _mapper.Map<Conversation>(@event);
                Conversation ReceptCon = _mapper.Map<Conversation>(@event);
                ReceptCon.UserId = @event.MsgRecipientId;
                ReceptCon.TargetId = @event.MsgSenderId;
                ReceptCon.UnreadCount += 1;
                ReceptCon.LastReadMessageId = null;
                _context.Conversations.AddRange(senderCon,ReceptCon);
                await _context.SaveChangesAsync();
            }
            else
            {
                Conversation senderCon = conversation;
                Conversation? ReceptCon = await _context.Conversations.FirstOrDefaultAsync(
                    x => x.UserId == @event.MsgRecipientId && x.TargetId == @event.MsgSenderId);
                if (ReceptCon is null)
                {
                    _logger.LogError("ConversationEventHandlerError：接收者会话对象缺失！Event:{Event}", JsonConvert.SerializeObject(@event));
                    throw new BaseException(CodeDefine.SYSTEM_ERROR);
                }

                //更新发送者conversation
                senderCon.UnreadCount = 0;
                senderCon.LastReadMessageId = @event.MessageId;
                senderCon.LastMessage = @event.MessageContent;
                senderCon.LastMessageTime = DateTime.Now;
                //更新接收者conversation
                ReceptCon.UnreadCount += 1;
                ReceptCon.LastMessage = @event.MessageContent;
                senderCon.LastMessageTime = DateTime.Now;
                _context.Conversations.UpdateRange(senderCon, ReceptCon);
                await _context.SaveChangesAsync();


            }
        }
    }
}