backend/internal/service/admin_group_service.go

package service

import (
	"context"
	"errors"

	"with_you/internal/dto"
	apperrors "with_you/internal/errors"
	"with_you/internal/model"
	"with_you/internal/repository"
)

// AdminGroupService 管理端群组服务接口
type AdminGroupService interface {
	// GetGroupList 获取群组列表（分页、搜索、筛选）
	GetGroupList(ctx context.Context, page, pageSize int, keyword, status, ownerID, startDate, endDate string) ([]dto.AdminGroupListResponse, int64, error)
	// GetGroupDetail 获取群组详情
	GetGroupDetail(ctx context.Context, groupID string) (*dto.AdminGroupDetailResponse, error)
	// GetGroupMembers 获取群组成员列表
	GetGroupMembers(ctx context.Context, groupID string, page, pageSize int) (*dto.AdminGroupMemberListResponse, error)
	// DeleteGroup 解散群组
	DeleteGroup(ctx context.Context, groupID string) error
	// UpdateGroupStatus 更新群组状态
	UpdateGroupStatus(ctx context.Context, groupID string, status string) (*dto.AdminGroupDetailResponse, error)
	// RemoveMember 移除群组成员
	RemoveMember(ctx context.Context, groupID string, userID string) error
	// TransferOwner 转让群主
	TransferOwner(ctx context.Context, groupID string, newOwnerID string) (*dto.AdminGroupDetailResponse, error)
}

// adminGroupServiceImpl 管理端群组服务实现
type adminGroupServiceImpl struct {
	groupRepo repository.GroupRepository
	userRepo  repository.UserRepository
}

// NewAdminGroupService 创建管理端群组服务
func NewAdminGroupService(
	groupRepo repository.GroupRepository,
	userRepo repository.UserRepository,
) AdminGroupService {
	return &adminGroupServiceImpl{
		groupRepo: groupRepo,
		userRepo:  userRepo,
	}
}

// GetGroupList 获取群组列表
func (s *adminGroupServiceImpl) GetGroupList(ctx context.Context, page, pageSize int, keyword, status, ownerID, startDate, endDate string) ([]dto.AdminGroupListResponse, int64, error) {
	groups, total, err := s.groupRepo.GetGroupList(page, pageSize, keyword, status, ownerID, startDate, endDate)
	if err != nil {
		return nil, 0, err
	}

	responses := make([]dto.AdminGroupListResponse, 0, len(groups))
	for _, group := range groups {
		response := dto.AdminGroupListResponse{
			ID:          group.ID,
			Name:        group.Name,
			Avatar:      group.Avatar,
			Description: group.Description,
			OwnerID:     group.OwnerID,
			MemberCount: group.MemberCount,
			MaxMembers:  group.MaxMembers,
			JoinType:    int(group.JoinType),
			MuteAll:     group.MuteAll,
			Status:      "active", // 默认状态为active，后续可以根据需要添加状态字段
			CreatedAt:   dto.FormatTime(group.CreatedAt),
			UpdatedAt:   dto.FormatTime(group.UpdatedAt),
		}

		// 获取群主信息
		if group.OwnerID != "" {
			owner, err := s.userRepo.GetByID(group.OwnerID)
			if err == nil && owner != nil {
				response.Owner = &dto.UserResponse{
					ID:        owner.ID,
					Username:  owner.Username,
					Nickname:  owner.Nickname,
					Avatar:    owner.Avatar,
					CreatedAt: dto.FormatTime(owner.CreatedAt),
				}
			}
		}

		// 获取帖子数量
		postCount, _ := s.groupRepo.GetGroupPostCount(group.ID)
		response.PostCount = postCount

		responses = append(responses, response)
	}

	return responses, total, nil
}

// GetGroupDetail 获取群组详情
func (s *adminGroupServiceImpl) GetGroupDetail(ctx context.Context, groupID string) (*dto.AdminGroupDetailResponse, error) {
	group, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return nil, err
	}

	response := &dto.AdminGroupDetailResponse{
		ID:          group.ID,
		Name:        group.Name,
		Avatar:      group.Avatar,
		Description: group.Description,
		OwnerID:     group.OwnerID,
		MemberCount: group.MemberCount,
		MaxMembers:  group.MaxMembers,
		JoinType:    int(group.JoinType),
		MuteAll:     group.MuteAll,
		Status:      "active",
		IsPublic:    true, // 默认为公开群组，后续可以根据需要添加字段
		CreatedAt:   dto.FormatTime(group.CreatedAt),
		UpdatedAt:   dto.FormatTime(group.UpdatedAt),
	}

	// 获取群主信息
	if group.OwnerID != "" {
		owner, err := s.userRepo.GetByID(group.OwnerID)
		if err == nil && owner != nil {
			response.Owner = dto.ConvertUserToResponse(owner)
		}
	}

	// 获取帖子数量
	postCount, _ := s.groupRepo.GetGroupPostCount(group.ID)
	response.PostCount = postCount

	// 获取最新公告
	announcement, _ := s.groupRepo.GetLatestAnnouncement(groupID)
	if announcement != nil {
		response.Announcement = &dto.GroupAnnouncementResponse{
			ID:        announcement.ID,
			GroupID:   announcement.GroupID,
			Content:   announcement.Content,
			AuthorID:  announcement.AuthorID,
			IsPinned:  announcement.IsPinned,
			CreatedAt: dto.FormatTime(announcement.CreatedAt),
		}
	}

	return response, nil
}

// GetGroupMembers 获取群组成员列表
func (s *adminGroupServiceImpl) GetGroupMembers(ctx context.Context, groupID string, page, pageSize int) (*dto.AdminGroupMemberListResponse, error) {
	// 先检查群组是否存在
	_, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return nil, errors.New("群组不存在")
	}

	members, total, err := s.groupRepo.GetMembersWithUserInfo(groupID, page, pageSize)
	if err != nil {
		return nil, err
	}

	list := make([]*dto.AdminGroupMemberResponse, 0, len(members))
	for _, member := range members {
		item := &dto.AdminGroupMemberResponse{
			ID:       member.ID,
			UserID:   member.UserID,
			Role:     member.Role,
			Nickname: member.Nickname,
			Muted:    member.Muted,
			JoinedAt: dto.FormatTime(member.JoinTime),
		}

		if member.User != nil {
			item.Username = member.User.Username
			item.Nickname = member.User.Nickname
			item.Avatar = member.User.Avatar
			item.User = &dto.UserResponse{
				ID:        member.User.ID,
				Username:  member.User.Username,
				Nickname:  member.User.Nickname,
				Avatar:    member.User.Avatar,
				CreatedAt: dto.FormatTime(member.User.CreatedAt),
			}
		}

		list = append(list, item)
	}

	return &dto.AdminGroupMemberListResponse{
		List:     list,
		Total:    total,
		Page:     page,
		PageSize: pageSize,
	}, nil
}

// DeleteGroup 解散群组
func (s *adminGroupServiceImpl) DeleteGroup(ctx context.Context, groupID string) error {
	// 先检查群组是否存在
	_, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return errors.New("群组不存在")
	}

	return s.groupRepo.Delete(groupID)
}

// UpdateGroupStatus 更新群组状态
func (s *adminGroupServiceImpl) UpdateGroupStatus(ctx context.Context, groupID string, status string) (*dto.AdminGroupDetailResponse, error) {
	// 先检查群组是否存在
	group, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return nil, errors.New("群组不存在")
	}

	// 验证状态值
	if status != "active" && status != "dissolved" {
		return nil, errors.New("无效的状态值")
	}

	// 如果状态是dissolved，则解散群组
	if status == "dissolved" {
		err = s.groupRepo.Delete(groupID)
		if err != nil {
			return nil, err
		}
	} else {
		// 更新群组状态
		err = s.groupRepo.UpdateGroupStatus(groupID, status)
		if err != nil {
			return nil, err
		}
		// 重新获取群组信息
		group, err = s.groupRepo.GetByID(groupID)
		if err != nil {
			return nil, err
		}
	}

	// 构建响应
	response := &dto.AdminGroupDetailResponse{
		ID:          group.ID,
		Name:        group.Name,
		Avatar:      group.Avatar,
		Description: group.Description,
		OwnerID:     group.OwnerID,
		MemberCount: group.MemberCount,
		MaxMembers:  group.MaxMembers,
		JoinType:    int(group.JoinType),
		MuteAll:     group.MuteAll,
		Status:      status,
		IsPublic:    true,
		CreatedAt:   dto.FormatTime(group.CreatedAt),
		UpdatedAt:   dto.FormatTime(group.UpdatedAt),
	}

	// 获取群主信息
	if group.OwnerID != "" {
		owner, err := s.userRepo.GetByID(group.OwnerID)
		if err == nil && owner != nil {
			response.Owner = &dto.UserResponse{
				ID:        owner.ID,
				Username:  owner.Username,
				Nickname:  owner.Nickname,
				Avatar:    owner.Avatar,
				CreatedAt: dto.FormatTime(owner.CreatedAt),
			}
		}
	}

	return response, nil
}

// RemoveMember 移除群组成员
func (s *adminGroupServiceImpl) RemoveMember(ctx context.Context, groupID string, userID string) error {
	// 先检查群组是否存在
	_, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return errors.New("群组不存在")
	}

	// 检查用户是否是群成员
	member, err := s.groupRepo.GetMember(groupID, userID)
	if err != nil {
		return errors.New("用户不是群组成员")
	}

	// 不能移除群主
	if member.Role == model.GroupRoleOwner {
		return errors.New("不能移除群主")
	}

	return s.groupRepo.RemoveMember(groupID, userID)
}

// TransferOwner 转让群主
// 委托 groupRepo.TransferOwner 在单个数据库事务内原子完成：
//   - 更新 group.owner_id 为新群主
//   - 原群主角色降级为普通成员
//   - 新群主角色升级为 owner
//
// 任何一步失败都会整体回滚，避免出现「两个群主」或「零群主」的数据不一致。
func (s *adminGroupServiceImpl) TransferOwner(ctx context.Context, groupID string, newOwnerID string) (*dto.AdminGroupDetailResponse, error) {
	// 校验群组存在
	group, err := s.groupRepo.GetByID(groupID)
	if err != nil {
		return nil, apperrors.ErrGroupNotFound
	}

	// 校验新群主是群成员
	newOwnerMember, err := s.groupRepo.GetMember(groupID, newOwnerID)
	if err != nil {
		return nil, apperrors.ErrNotGroupMember
	}
	// 新群主已是群主则无需转让
	if newOwnerMember.Role == model.GroupRoleOwner {
		return nil, apperrors.ErrInvalidOperation
	}

	// 校验当前群主信息存在
	if _, err := s.groupRepo.GetMember(groupID, group.OwnerID); err != nil {
		return nil, apperrors.ErrGroupNotFound
	}

	// 原子转让：所有写入在 groupRepo.TransferOwner 的单个事务内完成
	if err := s.groupRepo.TransferOwner(groupID, group.OwnerID, newOwnerID); err != nil {
		return nil, err
	}

	// 重新获取群组信息
	group, err = s.groupRepo.GetByID(groupID)
	if err != nil {
		return nil, err
	}

	// 构建响应
	response := &dto.AdminGroupDetailResponse{
		ID:          group.ID,
		Name:        group.Name,
		Avatar:      group.Avatar,
		Description: group.Description,
		OwnerID:     group.OwnerID,
		MemberCount: group.MemberCount,
		MaxMembers:  group.MaxMembers,
		JoinType:    int(group.JoinType),
		MuteAll:     group.MuteAll,
		Status:      "active",
		IsPublic:    true,
		CreatedAt:   dto.FormatTime(group.CreatedAt),
		UpdatedAt:   dto.FormatTime(group.UpdatedAt),
	}

	// 获取新群主信息
	if group.OwnerID != "" {
		owner, err := s.userRepo.GetByID(group.OwnerID)
		if err == nil && owner != nil {
			response.Owner = &dto.UserResponse{
				ID:        owner.ID,
				Username:  owner.Username,
				Nickname:  owner.Nickname,
				Avatar:    owner.Avatar,
				CreatedAt: dto.FormatTime(owner.CreatedAt),
			}
		}
	}

	return response, nil
}