Moderation subject: user:<email>

app/lib/admin/models.dart

@@ -98,30 +98,36 @@ class ModerationSubject {
   /// The kind of moderation as described by [ModerationSubjectKind], one of:
   /// - package,
   /// - package-version,
-  /// - publisher.
+  /// - publisher,
+  /// - user.
   final String kind;
 
   /// The local name part of the subject, may be a composite, one of:
   /// - <package>,
   /// - <package>/<version>,
-  /// - <publisherId>.
+  /// - <publisherId>,
+  /// - <email>.
   final String localName;
 
-  /// The package name of the subject (if not a publisher).
+  /// The package name of the subject (if not a publisher, or user).
   final String? package;
 
   /// The package version of the subject (if the version was specified).
   final String? version;
 
-  /// The publisher id (if not a package or package/version).
+  /// The publisher id (if not a package or package/version, or user).
   final String? publisherId;
 
+  /// The email address of the user (if not a package or publisher).
+  final String? email;
+
   ModerationSubject._({
     required this.kind,
     required this.localName,
     this.package,
     this.version,
     this.publisherId,
+    this.email,
   });
 
   factory ModerationSubject.package(String package, [String? version]) {
@@ -183,6 +189,13 @@ class ModerationSubject {
           localName: publisherId,
           publisherId: publisherId,
         );
+      case ModerationSubjectKind.user:
+        final email = parts[1];
+        return ModerationSubject._(
+          kind: kind,
+          localName: email,
+          email: email,
+        );
       default:
         return null;
     }
@@ -195,4 +208,5 @@ class ModerationSubjectKind {
   static const package = 'package';
   static const packageVersion = 'package-version';
   static const publisher = 'publisher';
+  static const user = 'user';
 }

app/lib/frontend/handlers/report.dart

@@ -47,7 +47,6 @@ Future<shelf.Response> reportPageHandler(shelf.Request request) async {
 Future<void> _verifySubject(ModerationSubject? subject) async {
   final package = subject?.package;
   final version = subject?.version;
-  final publisherId = subject?.publisherId;
   if (package != null) {
     final p = await packageBackend.lookupPackage(package);
     if (p == null) {
@@ -61,12 +60,23 @@ Future<void> _verifySubject(ModerationSubject? subject) async {
       }
     }
   }
+
+  final publisherId = subject?.publisherId;
   if (publisherId != null) {
     final p = await publisherBackend.getPublisher(publisherId);
     if (p == null) {
       throw NotFoundException('Publisher "$publisherId" does not exist.');
     }
   }
+
+  final email = subject?.email;
+  if (email != null) {
+    InvalidInputException.check(
+        isValidEmail(email), '"$email" is not a valid email.');
+
+    // NOTE: We are not going to lookup and reject the requests based on the
+    //       email address, as it would leak the existence of user accounts.
+  }
 }
 
 /// Handles POST /api/report

app/test/admin/models_test.dart

@@ -21,6 +21,7 @@ void main() {
       expect(ms.package, 'x');
       expect(ms.version, isNull);
       expect(ms.publisherId, isNull);
+      expect(ms.email, isNull);
     });
 
     test('package version', () {
@@ -30,6 +31,7 @@ void main() {
       expect(ms.package, 'x');
       expect(ms.version, '1.0.0');
       expect(ms.publisherId, isNull);
+      expect(ms.email, isNull);
     });
 
     test('publisher', () {
@@ -39,6 +41,17 @@ void main() {
       expect(ms.package, isNull);
       expect(ms.version, isNull);
       expect(ms.publisherId, 'example.com');
+      expect(ms.email, isNull);
+    });
+
+    test('user', () {
+      final ms = ModerationSubject.tryParse('user:a@example.com');
+      expect(ms!.kind, ModerationSubjectKind.user);
+      expect(ms.localName, 'a@example.com');
+      expect(ms.package, isNull);
+      expect(ms.version, isNull);
+      expect(ms.publisherId, isNull);
+      expect(ms.email, 'a@example.com');
     });
   });
 }