一阶段ok

internal/storage/attachment.go

@@ -0,0 +1,69 @@
+package storage
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/google/uuid"
+)
+
+// AttachmentStorage handles file operations for email attachments on disk.
+type AttachmentStorage struct {
+	baseDir string // cfg.Storage.AttachDir
+}
+
+// NewAttachmentStorage creates a new AttachmentStorage with the given base directory.
+func NewAttachmentStorage(baseDir string) *AttachmentStorage {
+	return &AttachmentStorage{baseDir: baseDir}
+}
+
+// Save writes attachment data to disk and returns the relative file path.
+// The filename is generated as {uuid}{ext} to avoid collisions.
+func (s *AttachmentStorage) Save(filename string, data []byte) (string, error) {
+	// Ensure the base directory exists
+	if err := os.MkdirAll(s.baseDir, 0755); err != nil {
+		return "", fmt.Errorf("创建附件目录失败: %w", err)
+	}
+
+	// Generate a unique filename with the original extension
+	ext := filepath.Ext(filename)
+	uniqueName := uuid.New().String() + ext
+
+	fullPath := filepath.Join(s.baseDir, uniqueName)
+	if err := os.WriteFile(fullPath, data, 0644); err != nil {
+		return "", fmt.Errorf("写入附件文件失败: %w", err)
+	}
+
+	return uniqueName, nil
+}
+
+// Read reads attachment data from disk given a relative path.
+func (s *AttachmentStorage) Read(relPath string) ([]byte, error) {
+	fullPath := s.FullPath(relPath)
+	data, err := os.ReadFile(fullPath)
+	if err != nil {
+		return nil, fmt.Errorf("读取附件文件失败: %w", err)
+	}
+	return data, nil
+}
+
+// Delete removes an attachment file from disk given a relative path.
+func (s *AttachmentStorage) Delete(relPath string) error {
+	fullPath := s.FullPath(relPath)
+	if err := os.Remove(fullPath); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("删除附件文件失败: %w", err)
+	}
+	return nil
+}
+
+// FullPath returns the absolute path for a given relative path.
+func (s *AttachmentStorage) FullPath(relPath string) string {
+	// Prevent directory traversal attacks
+	cleanRel := filepath.Clean(relPath)
+	if strings.HasPrefix(cleanRel, "..") {
+		cleanRel = strings.TrimPrefix(cleanRel, "../")
+	}
+	return filepath.Join(s.baseDir, cleanRel)
+}