backend/internal/service/post_ai_service.go

package service

import (
	"context"
	"fmt"
	"strings"

	"carrot_bbs/internal/pkg/openai"
	"carrot_bbs/internal/pkg/tencent"

	"go.uber.org/zap"
)

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
}

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)
}

type PostModerationReviewError struct {
	Reason string
}

func (e *PostModerationReviewError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "post needs manual review"
	}
	return "post needs manual review: " + e.Reason
}

func (e *PostModerationReviewError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "内容需要人工复审，请耐心等待"
	}
	return strings.TrimSpace(e.Reason)
}

func (e *PostModerationReviewError) IsReview() bool {
	return true
}

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
}

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 CommentModerationReviewError struct {
	Reason string
}

func (e *CommentModerationReviewError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "comment needs manual review"
	}
	return "comment needs manual review: " + e.Reason
}

func (e *CommentModerationReviewError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "评论需要人工复审，请耐心等待"
	}
	return strings.TrimSpace(e.Reason)
}

func (e *CommentModerationReviewError) IsReview() bool {
	return true
}

type ImageModerationRejectedError struct {
	Reason string
}

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

func (e *ImageModerationRejectedError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "图片未通过审核，请更换后重试"
	}
	return strings.TrimSpace(e.Reason)
}

type ImageModerationReviewError struct {
	Reason string
}

func (e *ImageModerationReviewError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "image needs manual review"
	}
	return "image needs manual review: " + e.Reason
}

func (e *ImageModerationReviewError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "图片需要人工复审，请耐心等待"
	}
	return strings.TrimSpace(e.Reason)
}

func (e *ImageModerationReviewError) IsReview() bool {
	return true
}

type BioModerationRejectedError struct {
	Reason string
}

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

func (e *BioModerationRejectedError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "个性签名未通过审核，请修改后重试"
	}
	return strings.TrimSpace(e.Reason)
}

type BioModerationReviewError struct {
	Reason string
}

func (e *BioModerationReviewError) Error() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "bio needs manual review"
	}
	return "bio needs manual review: " + e.Reason
}

func (e *BioModerationReviewError) UserMessage() string {
	if strings.TrimSpace(e.Reason) == "" {
		return "个性签名需要人工复审，请耐心等待"
	}
	return strings.TrimSpace(e.Reason)
}

func (e *BioModerationReviewError) IsReview() bool {
	return true
}

type PostAIService struct {
	openAIClient  openai.Client
	tencentClient tencent.Client
	strictMode    bool
}

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

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

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

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

func (s *PostAIService) ModeratePost(ctx context.Context, title, content string, images []string) error {
	if !s.IsEnabled() {
		return nil
	}

	if s.isOpenAIEnabled() {
		resp, err := s.openAIClient.ModeratePost(ctx, title, content, images)
		if err != nil {
			zap.L().Warn("AI post moderation failed, trying Tencent fallback",
				zap.Error(err),
			)
			return s.moderateTextWithTencent(ctx, title+" "+content,
				func(reason string) error { return &PostModerationRejectedError{Reason: reason} },
				func(reason string) error { return &PostModerationReviewError{Reason: reason} },
			)
		}

		switch resp.Result {
		case openai.ModerationResultBlock:
			return &PostModerationRejectedError{Reason: resp.Reason}
		case openai.ModerationResultReview:
			return &PostModerationReviewError{Reason: resp.Reason}
		default:
			return nil
		}
	}

	return s.moderateTextWithTencent(ctx, title+" "+content,
		func(reason string) error { return &PostModerationRejectedError{Reason: reason} },
		func(reason string) error { return &PostModerationReviewError{Reason: reason} },
	)
}

func (s *PostAIService) ModerateComment(ctx context.Context, content string, images []string) error {
	if !s.IsEnabled() {
		return nil
	}

	if s.isOpenAIEnabled() {
		resp, err := s.openAIClient.ModerateComment(ctx, content, images)
		if err != nil {
			zap.L().Warn("AI comment moderation failed, trying Tencent fallback",
				zap.Error(err),
			)
			return s.moderateTextWithTencent(ctx, content,
				func(reason string) error { return &CommentModerationRejectedError{Reason: reason} },
				func(reason string) error { return &CommentModerationReviewError{Reason: reason} },
			)
		}

		switch resp.Result {
		case openai.ModerationResultBlock:
			return &CommentModerationRejectedError{Reason: resp.Reason}
		case openai.ModerationResultReview:
			return &CommentModerationReviewError{Reason: resp.Reason}
		default:
			return nil
		}
	}

	return s.moderateTextWithTencent(ctx, content,
		func(reason string) error { return &CommentModerationRejectedError{Reason: reason} },
		func(reason string) error { return &CommentModerationReviewError{Reason: reason} },
	)
}

func (s *PostAIService) ModerateImage(ctx context.Context, imageURL string) error {
	if !s.isOpenAIEnabled() {
		return nil
	}

	resp, err := s.openAIClient.ModerateImage(ctx, imageURL)
	if err != nil {
		if s.strictMode {
			return err
		}
		zap.L().Warn("AI image moderation failed, fallback allow",
			zap.Error(err),
		)
		return nil
	}

	switch resp.Result {
	case openai.ModerationResultBlock:
		return &ImageModerationRejectedError{Reason: resp.Reason}
	case openai.ModerationResultReview:
		return &ImageModerationReviewError{Reason: resp.Reason}
	default:
		return nil
	}
}

func (s *PostAIService) ModerateBio(ctx context.Context, bio string) error {
	if !s.IsEnabled() {
		return nil
	}

	if s.isOpenAIEnabled() {
		resp, err := s.openAIClient.ModerateBio(ctx, bio)
		if err != nil {
			zap.L().Warn("AI bio moderation failed, trying Tencent fallback",
				zap.Error(err),
			)
			return s.moderateTextWithTencent(ctx, bio,
				func(reason string) error { return &BioModerationRejectedError{Reason: reason} },
				func(reason string) error { return &BioModerationReviewError{Reason: reason} },
			)
		}

		switch resp.Result {
		case openai.ModerationResultBlock:
			return &BioModerationRejectedError{Reason: resp.Reason}
		case openai.ModerationResultReview:
			return &BioModerationReviewError{Reason: resp.Reason}
		default:
			return nil
		}
	}

	return s.moderateTextWithTencent(ctx, bio,
		func(reason string) error { return &BioModerationRejectedError{Reason: reason} },
		func(reason string) error { return &BioModerationReviewError{Reason: reason} },
	)
}

func (s *PostAIService) moderateTextWithTencent(
	ctx context.Context,
	text string,
	rejectFactory func(string) error,
	reviewFactory func(string) error,
) error {
	if !s.isTencentEnabled() {
		if s.strictMode {
			return fmt.Errorf("no moderation service available")
		}
		zap.L().Warn("No moderation service available, fallback allow")
		return nil
	}

	resp, err := s.tencentClient.TextModeration(ctx, text)
	if err != nil {
		if s.strictMode {
			return err
		}
		zap.L().Warn("Tencent TMS moderation failed, fallback allow",
			zap.Error(err),
		)
		return nil
	}

	reason := resp.Label
	if len(resp.Keywords) > 0 {
		reason = resp.Label + ": " + strings.Join(resp.Keywords, ", ")
	}

	switch resp.Suggestion {
	case tencent.SuggestionBlock:
		return rejectFactory(reason)
	case tencent.SuggestionReview:
		return reviewFactory(reason)
	default:
		return nil
	}
}