jiang13-bbs/backend/service/announcement.go

package service

import (
	"errors"
	"strings"

	"github.com/freefire/jiang13-bbs/model"
	"gorm.io/gorm"
)

// 公告标签允许使用的预设色（服务端白名单，禁止透传任意颜色值）
var allowedTagColors = map[string]bool{
	"blue": true, "green": true, "orange": true,
	"red": true, "purple": true, "gray": true,
}

// AnnouncementService 站点公告服务
type AnnouncementService struct {
	db *gorm.DB
}

func NewAnnouncementService(db *gorm.DB) *AnnouncementService {
	return &AnnouncementService{db: db}
}

// AnnouncementInput 创建/更新公告的入参
type AnnouncementInput struct {
	Title     string `json:"title"`
	Content   string `json:"content"`
	Tag       string `json:"tag"`
	TagColor  string `json:"tag_color"`
	Published *bool  `json:"published"`
}

// normalize 清洗并校验入参，返回可直接落库的字段
func (in *AnnouncementInput) normalize(existing *model.Announcement) error {
	in.Title = strings.TrimSpace(in.Title)
	if in.Title == "" {
		return errors.New("标题不能为空")
	}
	if len([]rune(in.Title)) > 200 {
		return errors.New("标题不能超过 200 字")
	}
	in.Content = strings.TrimSpace(in.Content)
	if in.Content == "" {
		return errors.New("内容不能为空")
	}

	in.Tag = strings.TrimSpace(in.Tag)
	if in.Tag == "" {
		in.Tag = "公告"
	}
	if len([]rune(in.Tag)) > 32 {
		return errors.New("标签不能超过 32 字")
	}

	in.TagColor = strings.ToLower(strings.TrimSpace(in.TagColor))
	if in.TagColor == "" {
		if existing != nil && existing.TagColor != "" {
			in.TagColor = existing.TagColor
		} else {
			in.TagColor = "blue"
		}
	}
	if !allowedTagColors[in.TagColor] {
		return errors.New("不支持的标签颜色")
	}
	return nil
}

// applyTo 把入参写入模型（Published 为指针以区分"未传"与"显式 false"）
func (in *AnnouncementInput) applyTo(a *model.Announcement) {
	a.Title = in.Title
	a.Content = in.Content
	a.Tag = in.Tag
	a.TagColor = in.TagColor
	if in.Published != nil {
		a.Published = *in.Published
	}
}

// ListPublished 已发布公告（首页右栏 / 公开列表），按发布时间倒序
func (s *AnnouncementService) ListPublished(limit int) ([]model.Announcement, error) {
	if limit <= 0 {
		limit = 5
	}
	var list []model.Announcement
	err := s.db.Where("published = ?", true).
		Order("created_at DESC, id DESC").Limit(limit).Find(&list).Error
	return list, err
}

// GetPublished 取单条已发布公告（详情页）；草稿/不存在返回 gorm.ErrRecordNotFound
func (s *AnnouncementService) GetPublished(id uint) (*model.Announcement, error) {
	var a model.Announcement
	err := s.db.Where("published = ?", true).First(&a, id).Error
	if err != nil {
		return nil, err
	}
	return &a, nil
}

// ListAll 管理后台：含草稿，按更新时间倒序
func (s *AnnouncementService) ListAll() ([]model.Announcement, error) {
	var list []model.Announcement
	err := s.db.Order("created_at DESC, id DESC").Limit(100).Find(&list).Error
	return list, err
}

// Create 创建公告
func (s *AnnouncementService) Create(in *AnnouncementInput) (*model.Announcement, error) {
	if err := in.normalize(nil); err != nil {
		return nil, err
	}
	a := &model.Announcement{Published: true}
	in.applyTo(a)
	if err := s.db.Create(a).Error; err != nil {
		return nil, err
	}
	return a, nil
}

// Update 更新公告
func (s *AnnouncementService) Update(id uint, in *AnnouncementInput) (*model.Announcement, error) {
	var a model.Announcement
	if err := s.db.First(&a, id).Error; err != nil {
		return nil, err
	}
	if err := in.normalize(&a); err != nil {
		return nil, err
	}
	in.applyTo(&a)
	if err := s.db.Save(&a).Error; err != nil {
		return nil, err
	}
	return &a, nil
}

// Delete 删除公告（软删除）
func (s *AnnouncementService) Delete(id uint) error {
	result := s.db.Delete(&model.Announcement{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return gorm.ErrRecordNotFound
	}
	return nil
}