feat: add OpenGraph Link Preview Support

plugin/httpgetter/util.go

@@ -3,6 +3,8 @@ package httpgetter
 import (
 	"mime"
 	"net/http"
+	"net/url"
+	"strings"
 )
 
 func getMediatype(response *http.Response) (string, error) {
@@ -13,3 +15,24 @@ func getMediatype(response *http.Response) (string, error) {
 	}
 	return mediatype, nil
 }
+
+// NormalizeURLForCache normalizes a URL for use as a cache key.
+// It removes fragments (hash) and trailing slashes (except root) to ensure
+// that URLs like "https://example.com/" and "https://example.com" map to the same cache entry.
+func NormalizeURLForCache(urlStr string) string {
+	parsed, err := url.Parse(urlStr)
+	if err != nil {
+		// If parsing fails, return original URL
+		return urlStr
+	}
+
+	// Remove fragment (hash)
+	parsed.Fragment = ""
+
+	// Remove trailing slash from pathname (except root)
+	if parsed.Path != "/" && strings.HasSuffix(parsed.Path, "/") {
+		parsed.Path = strings.TrimSuffix(parsed.Path, "/")
+	}
+
+	return parsed.String()
+}

proto/api/v1/instance_service.proto

@@ -155,6 +155,8 @@ message InstanceSetting {
     int32 content_length_limit = 3;
     // enable_double_click_edit enables editing on double click.
     bool enable_double_click_edit = 4;
+    // enable_opengraph_link_previews enables OpenGraph link previews for links in memos.
+    bool enable_opengraph_link_previews = 5;
     // reactions is the list of reactions.
     repeated string reactions = 7;
   }

proto/api/v1/link_service.proto

@@ -0,0 +1,34 @@
+syntax = "proto3";
+
+package memos.api.v1;
+
+import "google/api/annotations.proto";
+import "google/api/client.proto";
+import "google/api/field_behavior.proto";
+
+option go_package = "gen/api/v1";
+
+service LinkService {
+  // GetLinkMetadata fetches OpenGraph metadata for a given URL.
+  rpc GetLinkMetadata(GetLinkMetadataRequest) returns (LinkMetadata) {
+    option (google.api.http) = {get: "/api/v1/links/metadata"};
+    option (google.api.method_signature) = "url";
+  }
+}
+
+// Request message for GetLinkMetadata method.
+message GetLinkMetadataRequest {
+  // The URL to fetch metadata for.
+  string url = 1 [(google.api.field_behavior) = REQUIRED];
+}
+
+// LinkMetadata contains OpenGraph metadata for a link.
+message LinkMetadata {
+  // The title of the link (from og:title or <title> tag).
+  string title = 1;
+  // The description of the link (from og:description or <meta name="description">).
+  string description = 2;
+  // The preview image URL (from og:image).
+  string image = 3;
+}
+