MetaLab/internal/service/post_service.go

package service

import (
	"errors"
	"fmt"
	"regexp"

	"metazone.cc/metalab/internal/common"
	"metazone.cc/metalab/internal/config"
	"metazone.cc/metalab/internal/model"

	"github.com/microcosm-cc/bluemonday"
	"gorm.io/gorm"
)

// sanitizePolicy Tiptap 输出 HTML 的消毒策略
// 前端 WYSIWYG 编辑器输出 HTML，由 bluemonday UGC 策略消毒
// 放行 code/pre 的 class/data-language 属性以保留代码高亮和语言标签
// 放行 span 元素及其 hljs-* class 以保留 highlight.js 语法高亮
// 放行 img 的 src/alt/title 属性以保留图片
var sanitizePolicy = func() *bluemonday.Policy {
	p := bluemonday.UGCPolicy()
	p.AllowElements("span")
	p.AllowAttrs("class", "data-language").OnElements("code", "pre")
	p.AllowAttrs("class").Matching(regexp.MustCompile("^hljs-")).OnElements("span")
	p.AllowAttrs("src", "alt", "title").OnElements("img")
	return p
}()

// PostService 帖子业务逻辑
type PostService struct {
	repo postStore
	ss   *config.SiteSettings
}

// NewPostService 构造函数
func NewPostService(repo postStore, ss *config.SiteSettings) *PostService {
	return &PostService{
		repo: repo,
		ss:   ss,
	}
}

// auditEnabled 审核是否开启
func (s *PostService) auditEnabled() bool {
	return s.ss.IsAuditEnabled()
}

// findPost 按 ID 查找帖子，区分"未找到"和"数据库错误"
func (s *PostService) findPost(id uint) (*model.Post, error) {
	post, err := s.repo.FindByID(id)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, common.ErrPostNotFound
		}
		return nil, fmt.Errorf("查询帖子失败: %w", err)
	}
	return post, nil
}

// findPostWithAuthor 按 ID 查找帖子（含作者名），区分"未找到"和"数据库错误"
func (s *PostService) findPostWithAuthor(id uint) (*model.Post, error) {
	post, err := s.repo.FindByIDWithAuthor(id)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, common.ErrPostNotFound
		}
		return nil, fmt.Errorf("查询帖子失败: %w", err)
	}
	return post, nil
}

// sanitizeHTML 对 Tiptap 输出的 HTML 进行消毒
// 前端 WYSIWYG 编辑器直接输出 HTML，后端仅做安全消毒
func (s *PostService) sanitizeHTML(body string) string {
	return sanitizePolicy.Sanitize(body)
}

// Create 创建帖子
func (s *PostService) Create(userID uint, title, body string) (*model.Post, error) {
	bodyHTML := s.sanitizeHTML(body)

	status := model.PostStatusApproved
	if s.auditEnabled() {
		status = model.PostStatusDraft
	}

	post := &model.Post{
		Title:        title,
		Body:         body,
		BodyHTML:     bodyHTML,
		UserID:       userID,
		Status:       status,
		AllowComment: true,
	}
	if err := s.repo.Create(post); err != nil {
		return nil, err
	}
	return post, nil
}

// GetByID 按 ID 获取帖子（含作者名，仅 approved 公开可见）
func (s *PostService) GetByID(id uint) (*model.Post, error) {
	return s.findPostWithAuthor(id)
}

// List 公开帖子列表（仅 approved）
func (s *PostService) List(keyword string, page, pageSize int) ([]model.Post, int64, error) {
	p := common.Pagination{Page: page, PageSize: pageSize}
	p.DefaultPagination()
	return s.repo.FindPageable(keyword, p.Offset(), p.PageSize)
}

// ListAdmin 管理后台帖子列表（全状态）
func (s *PostService) ListAdmin(keyword, status string, page, pageSize int) ([]model.Post, int64, error) {
	p := common.Pagination{Page: page, PageSize: pageSize}
	p.DefaultPagination()
	return s.repo.FindAdminPageable(keyword, status, p.Offset(), p.PageSize)
}

// Update 编辑帖子（权限在 controller 层检查）
func (s *PostService) Update(postID uint, title, body string) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}

	if post.Status == model.PostStatusPending || post.Status == model.PostStatusLocked {
		return common.ErrPostCannotEdit
	}

	post.Title = title
	post.Body = body
	post.BodyHTML = s.sanitizeHTML(body)

	// rejected 状态编辑后自动重置为 draft
	if post.Status == model.PostStatusRejected {
		post.Status = model.PostStatusDraft
		post.RejectReason = ""
	}

	return s.repo.Update(post)
}

// Delete 软删除（权限在 controller 层检查）
func (s *PostService) Delete(postID uint) error {
	return s.repo.SoftDelete(postID)
}

// SubmitForAudit 提交审核：draft → pending
func (s *PostService) SubmitForAudit(postID uint) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}
	if post.Status != model.PostStatusDraft && post.Status != model.PostStatusRejected {
		return common.ErrPostCannotSubmit
	}
	post.Status = model.PostStatusPending
	return s.repo.Update(post)
}

// Approve 审核通过：pending → approved
func (s *PostService) Approve(postID uint) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}
	if post.Status != model.PostStatusPending {
		return common.ErrPostCannotApprove
	}
	post.Status = model.PostStatusApproved
	post.RejectReason = ""
	return s.repo.Update(post)
}

// Reject 退回：pending/approved → rejected
func (s *PostService) Reject(postID uint, reason string) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}
	if post.Status != model.PostStatusPending && post.Status != model.PostStatusApproved {
		return common.ErrPostCannotReject
	}
	post.Status = model.PostStatusRejected
	post.RejectReason = reason
	return s.repo.Update(post)
}

// Lock 锁定：任意状态 → locked（管理员可随时锁定）
func (s *PostService) Lock(postID uint) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}
	post.Status = model.PostStatusLocked
	return s.repo.Update(post)
}

// Unlock 解锁：locked → 草稿
func (s *PostService) Unlock(postID uint) error {
	post, err := s.findPost(postID)
	if err != nil {
		return err
	}
	if post.Status != model.PostStatusLocked {
		return common.ErrPostCannotUnlock
	}
	post.Status = model.PostStatusDraft
	return s.repo.Update(post)
}

// Restore 恢复软删除
func (s *PostService) Restore(postID uint) error {
	return s.repo.Restore(postID)
}