using GroupService.Domain.Events;
using GroupService.Infrastructure;
using IM.Commons.IntegrationEvents;
using MassTransit;
using MediatR;

namespace GroupService.WebApi.Application.EventHandler
{
    public class GroupMemberJoinedHandler : INotificationHandler<GroupMemberJoinedDomainEvent>
    {
        private readonly IPublishEndpoint endpoint;
        private readonly GroupDbContext db;

        public GroupMemberJoinedHandler(IPublishEndpoint endpoint, GroupDbContext db)
        {
            this.endpoint = endpoint;
            this.db = db;
        }

        public async Task Handle(GroupMemberJoinedDomainEvent notification, CancellationToken cancellationToken)
        {
            var member = notification.Member;
            // 用 FindAsync 而非 FirstOrDefaultAsync：群可能刚创建尚未提交到数据库，FindAsync 先查内存跟踪器
            var group = await db.Set<Domain.Entities.Group>().FindAsync(member.GroupId);
            var groupName = group?.Name ?? "群聊";
            var groupAvatar = group?.Avatar;

            await endpoint.Publish(new GroupMemberJoinedEvent(member.Id,
                member.UserId, member.GroupId, member.GroupNickName, member.Avatar,
                member.Role.ToString(), groupName, groupAvatar), cancellationToken);
        }
    }
}