migrate from github

internal/media/core.go

@@ -0,0 +1,84 @@
+package media
+
+import (
+	"fmt"
+	"mime"
+	"net/http"
+	"path/filepath"
+	"strings"
+
+	"github.com/XingfenD/yoresee_doc/pkg/storage"
+)
+
+func normalizeMIMEType(contentType string) string {
+	normalized := strings.ToLower(strings.TrimSpace(contentType))
+	if idx := strings.Index(normalized, ";"); idx > 0 {
+		normalized = strings.TrimSpace(normalized[:idx])
+	}
+	if normalized == "image/jpg" {
+		return "image/jpeg"
+	}
+	return normalized
+}
+
+func NormalizeContentTypeByAllowed(file []byte, provided string, allowed map[string]string) string {
+	normalized := normalizeMIMEType(provided)
+	if _, ok := allowed[normalized]; ok {
+		return normalized
+	}
+
+	detected := normalizeMIMEType(http.DetectContentType(file))
+	if _, ok := allowed[detected]; ok {
+		return detected
+	}
+	return ""
+}
+
+func IsContentTypeAllowed(contentType string, allowed map[string]string) bool {
+	_, ok := allowed[normalizeMIMEType(contentType)]
+	return ok
+}
+
+func ResolveExtension(filename, contentType string, allowed map[string]string, defaultExt string) string {
+	ext := strings.TrimSpace(strings.ToLower(filepath.Ext(filename)))
+	if ext != "" {
+		for _, candidate := range allowed {
+			if ext == candidate {
+				return ext
+			}
+		}
+	}
+
+	contentType = normalizeMIMEType(contentType)
+	if mapped, ok := allowed[contentType]; ok {
+		return mapped
+	}
+
+	exts, err := mime.ExtensionsByType(contentType)
+	if err == nil && len(exts) > 0 {
+		for _, candidate := range exts {
+			candidate = strings.TrimSpace(strings.ToLower(candidate))
+			for _, allowedExt := range allowed {
+				if candidate == allowedExt {
+					return candidate
+				}
+			}
+		}
+	}
+	return strings.TrimSpace(strings.ToLower(defaultExt))
+}
+
+func BuildVersionedObjectKey(prefix, ownerExternalID string, version int64, ext string) string {
+	prefix = strings.Trim(strings.TrimSpace(prefix), "/")
+	if prefix == "" {
+		return fmt.Sprintf("%s/v%d%s", ownerExternalID, version, ext)
+	}
+	return fmt.Sprintf("%s/%s/v%d%s", prefix, ownerExternalID, version, ext)
+}
+
+func BuildStorageURL(objectKey string) string {
+	if strings.TrimSpace(objectKey) == "" {
+		return ""
+	}
+	return storage.BuildPublicObjectPath(objectKey)
+}