feat: 添加日志管理和敏感词过滤功能

- 新增日志管理模块：操作日志、登录日志、数据变更日志
- 新增敏感词过滤器 (sanitizer)
- 新增日志异步写入管理器
- 新增日志定时清理服务
- 优化帖子相关服务和上传服务

internal/service/upload_service.go

@@ -9,6 +9,7 @@ import (
 	"image/jpeg"
 	"image/png"
 	"io"
+	"log"
 	"mime"
 	"mime/multipart"
 	"net/http"
@@ -16,6 +17,7 @@ import (
 	"strings"
 
 	"carrot_bbs/internal/pkg/s3"
+	"github.com/disintegration/imaging"
 
 	_ "golang.org/x/image/bmp"
 	_ "golang.org/x/image/tiff"
@@ -27,6 +29,13 @@ type UploadService struct {
 	userService UserService
 }
 
+// 预览图配置
+const (
+	PreviewMaxWidth  = 300 // 列表/网格模式最大宽度
+	PreviewMaxHeight = 800 // 详情页最大高度
+	PreviewQuality   = 70  // WebP 质量
+)
+
 // NewUploadService 创建上传服务
 func NewUploadService(s3Client *s3.Client, userService UserService) *UploadService {
 	return &UploadService{
@@ -35,25 +44,31 @@ func NewUploadService(s3Client *s3.Client, userService UserService) *UploadServi
 	}
 }
 
-// UploadImage 上传图片
-func (s *UploadService) UploadImage(ctx context.Context, file *multipart.FileHeader) (string, error) {
+// UploadImage 上传图片（返回原图URL和预览图URL）
+func (s *UploadService) UploadImage(ctx context.Context, file *multipart.FileHeader) (string, string, string, error) {
 	processedData, contentType, ext, err := prepareImageForUpload(file)
 	if err != nil {
-		return "", err
+		return "", "", "", err
 	}
 
 	// 压缩后再计算哈希，确保同一压缩结果映射同一对象名
 	hash := sha256.Sum256(processedData)
 	hashStr := fmt.Sprintf("%x", hash)
 
+	// 上传原图
 	objectName := fmt.Sprintf("images/%s%s", hashStr, ext)
-
 	url, err := s.s3Client.UploadData(ctx, objectName, processedData, contentType)
 	if err != nil {
-		return "", fmt.Errorf("failed to upload to S3: %w", err)
+		return "", "", "", fmt.Errorf("failed to upload to S3: %w", err)
 	}
 
-	return url, nil
+	// 生成预览图
+	previewURL, previewURLLarge, err := s.GeneratePreviewImages(ctx, processedData, hashStr)
+	if err != nil {
+		log.Printf("[WARN] Failed to generate preview images: %v", err)
+	}
+
+	return url, previewURL, previewURLLarge, nil
 }
 
 // getExtFromContentType 根据Content-Type获取文件扩展名
@@ -272,3 +287,73 @@ func normalizeImageContentType(contentType string) string {
 		return contentType
 	}
 }
+
+// GeneratePreviewImages 生成预览图
+func (s *UploadService) GeneratePreviewImages(ctx context.Context, originalData []byte, hash string) (previewURL, previewURLLarge string, err error) {
+	img, _, err := image.Decode(bytes.NewReader(originalData))
+	if err != nil {
+		return "", "", fmt.Errorf("failed to decode image: %w", err)
+	}
+
+	bounds := img.Bounds()
+	originalWidth := bounds.Dx()
+	originalHeight := bounds.Dy()
+
+	// 生成普通预览图（列表/网格模式）
+	previewURL, err = s.generatePreview(ctx, img, originalWidth, originalHeight, "preview", PreviewMaxWidth, hash)
+	if err != nil {
+		log.Printf("[WARN] Failed to generate preview: %v", err)
+	}
+
+	// 生成大预览图（详情页）
+	previewURLLarge, err = s.generatePreview(ctx, img, originalWidth, originalHeight, "large", PreviewMaxHeight, hash)
+	if err != nil {
+		log.Printf("[WARN] Failed to generate large preview: %v", err)
+	}
+
+	return previewURL, previewURLLarge, nil
+}
+
+// generatePreview 生成单个预览图
+func (s *UploadService) generatePreview(ctx context.Context, img image.Image, originalWidth, originalHeight int, mode string, maxDim int, hash string) (string, error) {
+	var targetWidth, targetHeight int
+
+	// 计算目标尺寸
+	if originalWidth > originalHeight {
+		// 宽图：按宽度缩放
+		if originalWidth > maxDim {
+			targetWidth = maxDim
+			targetHeight = int(float64(originalHeight) * float64(maxDim) / float64(originalWidth))
+		} else {
+			return "", nil // 图片足够小，不需要生成预览图
+		}
+	} else {
+		// 高图：按高度缩放
+		if originalHeight > maxDim {
+			targetHeight = maxDim
+			targetWidth = int(float64(originalWidth) * float64(maxDim) / float64(originalHeight))
+		} else {
+			return "", nil // 图片足够小，不需要生成预览图
+		}
+	}
+
+	// 缩放图片（使用高质量 Lanczos 算法）
+	scaledImg := imaging.Resize(img, targetWidth, targetHeight, imaging.Lanczos)
+
+	// 编码为 JPEG（WebP 在某些设备上可能不支持，使用 JPEG 保证兼容性）
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, scaledImg, &jpeg.Options{Quality: PreviewQuality}); err != nil {
+		return "", fmt.Errorf("failed to encode jpeg: %w", err)
+	}
+
+	// 构建对象名：thumbnails/{hash}_{mode}.jpg
+	objectName := fmt.Sprintf("thumbnails/%s_%s.jpg", hash, mode)
+
+	// 上传到 S3
+	url, err := s.s3Client.UploadData(ctx, objectName, buf.Bytes(), "image/jpeg")
+	if err != nil {
+		return "", fmt.Errorf("failed to upload preview: %w", err)
+	}
+
+	return url, nil
+}