92 lines
3.7 KiB
C#
92 lines
3.7 KiB
C#
using BuildFlow.Platform.Application.Users.DTOs;
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using BuildFlow.Platform.Application.Users.Queries;
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using IM.Application.Chat.DTOs;
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using IM.Application.Chat.Queries;
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using IM.Domain.Common;
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using IM.Infrastructure.Persistence;
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using MediatR;
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namespace IM.Application.Chat.Handlers;
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/// <summary>
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/// 用户会话列表查询处理器。聚合最后消息与未读数。
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/// </summary>
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public class GetConversationsQueryHandler(
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ImDbContext db,
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IMediator mediator,
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IUnreadCounter unreadCounter)
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: IRequestHandler<GetConversationsQuery, List<ConversationDto>>
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{
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public async Task<List<ConversationDto>> Handle(GetConversationsQuery request, CancellationToken ct)
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{
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// 一次性 Include 参与者与群组导航属性，避免 N+1 查询
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var participants = await db.ConversationParticipants
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.Where(p => p.UserId == request.UserId)
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.Include(p => p.ConversationEntity)
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.ThenInclude(c => c.Participants)
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.Include(p => p.ConversationEntity)
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.ThenInclude(c => c.GroupEntity)
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.Where(p => !p.ConversationEntity.IsDeleted)
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// 排序：置顶优先（PinnedAt 倒序），其次按最后消息时间倒序
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.OrderByDescending(p => p.IsPinned)
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.ThenByDescending(p => p.PinnedAt)
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.ThenByDescending(p => p.ConversationEntity.LastMessageAt)
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.ToListAsync(ct);
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// 私聊会话需解析"对方"用户以展示头像/昵称；批量收集去重后一次性查询 Platform，避免逐会话往返。
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var otherUserIds = participants
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.Where(p => p.ConversationEntity.Type == Domain.Enums.ConversationTypeEnum.Private)
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.Select(p => p.ConversationEntity.Participants
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.FirstOrDefault(op => op.UserId != request.UserId)?.UserId)
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.Where(id => id.HasValue)
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.Select(id => id!.Value)
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.Distinct()
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.ToList();
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var users = otherUserIds.Count > 0
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? await mediator.Send(new GetUserSummariesQuery(otherUserIds), ct)
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: new Dictionary<Guid, UserSummaryDto>();
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var redisUnread = await unreadCounter.GetByUserAsync(
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request.UserId,
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participants.Select(p => p.ConversationId),
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ct);
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return participants.Select(p =>
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{
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string? otherUserName = null;
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string? otherUserAvatar = null;
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Guid? otherUserId = null;
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if (p.ConversationEntity.Type == Domain.Enums.ConversationTypeEnum.Private)
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{
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var otherParticipant = p.ConversationEntity.Participants
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.FirstOrDefault(op => op.UserId != request.UserId);
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if (otherParticipant is not null)
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{
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otherUserId = otherParticipant.UserId;
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var userInfo = users.GetValueOrDefault(otherParticipant.UserId);
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otherUserName = userInfo?.Username;
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otherUserAvatar = userInfo?.Avatar;
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}
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}
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return new ConversationDto(
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p.ConversationEntity.Id,
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p.ConversationEntity.Type,
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p.ConversationEntity.LastMessageContent,
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p.ConversationEntity.LastMessageAt,
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redisUnread.TryGetValue(p.ConversationId, out var unreadCount) ? unreadCount : p.UnreadCount,
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p.ConversationEntity.GroupEntity?.Name,
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p.ConversationEntity.GroupEntity?.Avatar,
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p.ConversationEntity.GroupEntity?.Id,
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otherUserId,
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otherUserName,
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otherUserAvatar,
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p.IsPinned,
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p.IsMuted,
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p.Remark);
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}).ToList();
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}
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}
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