IM_NEW/MessageService.WebApi/Application/EventHandlers/ConversationAddHandler.cs

using IM.Commons.IntegrationEvents;
using MassTransit;
using MessageService.Domain.IReposities;
using MessageService.Infrastructure;
using Microsoft.EntityFrameworkCore;
using MySqlConnector;

namespace MessageService.WebApi.Application.EventHandlers
{
    public class ConversationAddHandler : IConsumer<GroupMemberJoinedEvent>,
        IConsumer<FriendAddedEvent>, IConsumer<GroupMemberLeftEvent>
    {

        private readonly IConversationReposity reposity;
        private readonly MessageDbContext messageDb;

        public ConversationAddHandler(IConversationReposity reposity, MessageDbContext messageDb)
        {
            this.reposity = reposity;
            this.messageDb = messageDb;
        }

        public async Task Consume(ConsumeContext<GroupMemberJoinedEvent> context)
        {
            var @event = context.Message;
            var existing = await reposity.FindActiveAsync(@event.UserId, @event.GroupId, Domain.Enums.ChatType.GROUP, context.CancellationToken);
            if (existing is not null)
            {
                return;
            }
            reposity.Create(new Domain.Entities.Conversation(
                userId: @event.UserId,
                targetId: @event.GroupId,
                targetAvatar: @event.GroupAvatar ?? @event.Avatar,
                targetName: @event.GroupName,
                lastReadSequenceId: null,
                unreadCount:0,
                chatType: Domain.Enums.ChatType.GROUP,
                lastMessage: string.Empty
                ));

            await SaveIdempotentlyAsync(context.CancellationToken);
        }

        public async Task Consume(ConsumeContext<FriendAddedEvent> context)
        {
            var @event = context.Message;
            var existing = await reposity.FindActiveAsync(@event.OwnerId, @event.TargetId, Domain.Enums.ChatType.PRIVATE, context.CancellationToken);
            if (existing is not null)
            {
                return;
            }
            reposity.Create(new Domain.Entities.Conversation(
                userId: @event.OwnerId,
                targetId: @event.TargetId,
                targetAvatar: @event.TargetAvatar,
                targetName: @event.TargetNickName,
                lastReadSequenceId: null,
                unreadCount: 0,
                chatType: Domain.Enums.ChatType.PRIVATE,
                lastMessage: string.Empty
                ));

            await SaveIdempotentlyAsync(context.CancellationToken);
        }

        public async Task Consume(ConsumeContext<GroupMemberLeftEvent> context)
        {
            var conversation = await reposity.FindActiveAsync(
                context.Message.UserId,
                context.Message.GroupId,
                Domain.Enums.ChatType.GROUP,
                context.CancellationToken);
            if (conversation is not null)
            {
                conversation.SoftDelete();
            }
            await messageDb.SaveChangesAsync(context.CancellationToken);
        }

        private async Task SaveIdempotentlyAsync(CancellationToken cancellationToken)
        {
            try
            {
                await messageDb.SaveChangesAsync(cancellationToken);
            }
            catch (DbUpdateException exception) when (exception.InnerException is MySqlException { Number: 1062 })
            {
                messageDb.ChangeTracker.Clear();
            }
        }
    }
}