backend/internal/service/post_ai_service.go

package service

import (
	"context"
	"log"
	"strings"

	"carrot_bbs/internal/pkg/openai"
)

// PostModerationRejectedError 帖子审核拒绝错误
type PostModerationRejectedError struct {
	Reason string
}

func (e *PostModerationRejectedError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "post rejected by moderation"
	}
	return "post rejected by moderation: " + e.Reason
}

// UserMessage 返回给前端的用户可读文案
func (e *PostModerationRejectedError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "内容未通过审核，请修改后重试"
	}
	return strings.TrimSpace(e.Reason)
}

// CommentModerationRejectedError 评论审核拒绝错误
type CommentModerationRejectedError struct {
	Reason string
}

func (e *CommentModerationRejectedError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "comment rejected by moderation"
	}
	return "comment rejected by moderation: " + e.Reason
}

// UserMessage 返回给前端的用户可读文案
func (e *CommentModerationRejectedError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "评论未通过审核，请修改后重试"
	}
	return strings.TrimSpace(e.Reason)
}

type PostAIService struct {
	openAIClient openai.Client
}

func NewPostAIService(openAIClient openai.Client) *PostAIService {
	return &PostAIService{
		openAIClient: openAIClient,
	}
}

func (s *PostAIService) IsEnabled() bool {
	return s != nil && s.openAIClient != nil && s.openAIClient.IsEnabled()
}

// ModeratePost 审核帖子内容，返回 nil 表示通过
func (s *PostAIService) ModeratePost(ctx context.Context, title, content string, images []string) error {
	if !s.IsEnabled() {
		return nil
	}

	approved, reason, err := s.openAIClient.ModeratePost(ctx, title, content, images)
	if err != nil {
		if s.openAIClient.Config().StrictModeration {
			return err
		}
		log.Printf("[WARN] AI moderation failed, fallback allow: %v", err)
		return nil
	}
	if !approved {
		return &PostModerationRejectedError{Reason: reason}
	}
	return nil
}

// ModerateComment 审核评论内容，返回 nil 表示通过
func (s *PostAIService) ModerateComment(ctx context.Context, content string, images []string) error {
	if !s.IsEnabled() {
		return nil
	}

	approved, reason, err := s.openAIClient.ModerateComment(ctx, content, images)
	if err != nil {
		if s.openAIClient.Config().StrictModeration {
			return err
		}
		log.Printf("[WARN] AI comment moderation failed, fallback allow: %v", err)
		return nil
	}
	if !approved {
		return &CommentModerationRejectedError{Reason: reason}
	}
	return nil
}