IM/backend/IM_API/Services/MessageService.cs

using AutoMapper;
using IM_API.Dtos;
using IM_API.Exceptions;
using IM_API.Interface.Services;
using IM_API.Models;
using IM_API.Tools;
using Microsoft.EntityFrameworkCore;

namespace IM_API.Services
{
    public class MessageService : IMessageSevice
    {
        private readonly ImContext _context;
        private readonly ILogger<MessageService> _logger;
        private readonly IMapper _mapper;
        public MessageService(ImContext context, ILogger<MessageService> logger, IMapper mapper)
        {
            _context = context;
            _logger = logger;
            _mapper = mapper;
        }

        public async Task<List<MessageBaseDto>> GetMessagesAsync(int userId, int conversationId, int? msgId, int? pageSize, bool desc)
        {
            //获取会话信息，用于获取双方聊天的唯一标识streamkey
            Conversation? conversation = await _context.Conversations.FirstOrDefaultAsync(
                x => x.Id == conversationId && x.UserId == userId
                );
            if (conversation is null) throw new BaseException(CodeDefine.CONVERSATION_NOT_FOUND);
            var query = _context.Messages.AsQueryable();
            if(msgId != null)
            {
                query = query.Where(
                    x => x.StreamKey == conversation.StreamKey && x.Id < msgId.Value
                    )
                    .OrderByDescending(x => x.Id);
            }
            else
            {
                query = query.Where(
                    x => x.StreamKey == conversation.StreamKey && x.Id > conversation.LastReadMessageId
                    );
            }
            if(pageSize != null)
            {
                query = query.Take(pageSize.Value);
            }
            var msgList = await query
                .ToListAsync();
            msgList = msgList
                .OrderBy(x => x.Created)
                .ThenBy(t => t.Id)
                .ToList();
            return _mapper.Map<List<MessageBaseDto>>(msgList);
        }

        public Task<int> GetUnreadCountAsync(int userId)
        {
            throw new NotImplementedException();
        }

        public Task<List<MessageBaseDto>> GetUnreadMessagesAsync(int userId)
        {
            throw new NotImplementedException();
        }

        public Task<bool> MarkAsReadAsync(int userId, long messageId)
        {
            throw new NotImplementedException();
        }

        public Task<bool> MarkConversationAsReadAsync(int userId, int? userBId, int? groupId)
        {
            throw new NotImplementedException();
        }

        public Task<bool> RecallMessageAsync(int userId, int messageId)
        {
            throw new NotImplementedException();
        }
        #region 发送群消息
        public async Task<bool> SendGroupMessageAsync(int senderId, int groupId, MessageBaseDto dto)
        {
            //判断群存在
            var isExist = await _context.Groups.AnyAsync(x => x.Id == groupId);
            if (!isExist) throw new BaseException(CodeDefine.GROUP_NOT_FOUND);
            //判断是否是群成员
            var isMember = await _context.GroupMembers.AnyAsync(x => x.GroupId == groupId && x.UserId == senderId);
            if (!isMember) throw new BaseException(CodeDefine.NO_GROUP_PERMISSION);
            var message = _mapper.Map<Message>(dto);
            message.Sender = senderId;
            message.StreamKey = StreamKeyBuilder.Group(groupId);
            _context.Messages.Add(message);
            await _context.SaveChangesAsync();
            return true;

        }
        #endregion
        #region 发送私聊消息
        public async Task<bool> SendPrivateMessageAsync(int senderId, int receiverId, MessageBaseDto dto)
        {
            bool isExist = await _context.Friends.AnyAsync(x => x.FriendId == receiverId);
            if (!isExist) throw new BaseException(CodeDefine.FRIEND_RELATION_NOT_FOUND);
            var message = _mapper.Map<Message>(dto);
            message.Sender = senderId;
            //生成消息流唯一标识符
            message.StreamKey = StreamKeyBuilder.Private(dto.SenderId, dto.ReceiverId);
            _context.Messages.Add(message);
            await _context.SaveChangesAsync();
            return true;
        }
        #endregion
    }
}