Extract URL manipulation to its own file, and add unit tests.

Author: ditman

packages/google_sign_in/lib/src/fife.dart

@@ -0,0 +1,53 @@
+/// A regular expression that matches against the "size directive" path
+/// segment of Google profile image URLs.
+///
+/// The format is is "`/sNN-c/`", where `NN` is the max width/height of the
+/// image, and "`c`" indicates we want the image cropped.
+final RegExp sizeDirective = RegExp(r'^s[0-9]{1,5}(-c)?$');
+
+/// Adds sizing information to [photoUrl], inserted as the last path segment
+/// before the image filename. The format is described in [sizeDirective].
+///
+/// Falls back to the default profile photo if [photoUrl] is [null].
+String sizedProfileImageUrl(String photoUrl, double size) {
+  if (photoUrl == null) {
+    // If the user has no profile photo and no display name, fall back to
+    // the default profile photo as a last resort.
+    return 'https://lh3.googleusercontent.com/a/default-user=s${size.round()}-c';
+  }
+  final Uri profileUri = Uri.parse(photoUrl);
+  final List<String> pathSegments = List<String>.from(profileUri.pathSegments);
+  if (pathSegments.length <= 2) {
+    /// New URLs may have directives at the end of the URL, like "`=sNN-c`".
+    /// Each filter is separated by dashes. Filters may contain = signs:
+    /// "`=s120-c-fSoften=1,50,0`"
+    final String imagePath = pathSegments.last;
+    // Locate the first =
+    final int directiveSeparator = imagePath.indexOf('=');
+    if (directiveSeparator >= 0) {
+      // Split the image URL by the first =
+      final String image = imagePath.substring(0, directiveSeparator);
+      final String directive = imagePath.substring(directiveSeparator + 1);
+      // Split the second half by -
+      final Set<String> directives = Set<String>.from(directive.split('-'))
+        // Remove the size directive, if present, and empty values
+        ..removeWhere((String s) => s.isEmpty || sizeDirective.hasMatch(s))
+        // Add the size and crop directives
+        ..addAll(<String>['c', 's${size.round()}']);
+
+      pathSegments.last = '$image=${directives.join("-")}';
+    } else {
+      pathSegments.last = '${pathSegments.last}=c-s${size.round()}';
+    }
+  } else {
+    // Old style URLs
+    pathSegments
+      ..removeWhere(sizeDirective.hasMatch)
+      ..insert(pathSegments.length - 1, 's${size.round()}-c');
+  }
+  return Uri(
+    scheme: profileUri.scheme,
+    host: profileUri.host,
+    pathSegments: pathSegments,
+  ).toString();
+}

packages/google_sign_in/lib/widgets.dart

@@ -8,6 +8,7 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
 import 'src/common.dart';
+import 'src/fife.dart' as fife;
 
 /// Builds a CircleAvatar profile image of the appropriate resolution
 class GoogleUserCircleAvatar extends StatelessWidget {
@@ -33,7 +34,7 @@ class GoogleUserCircleAvatar extends StatelessWidget {
   ///
   /// The format is is "`/sNN-c/`", where `NN` is the max width/height of the
   /// image, and "`c`" indicates we want the image cropped.
-  static final RegExp sizeDirective = RegExp(r'^s[0-9]{1,5}(-c)?$');
+  static final RegExp sizeDirective = fife.sizeDirective;
 
   /// The Google user's identity; guaranteed to be non-null.
   final GoogleIdentity identity;
@@ -67,35 +68,6 @@ class GoogleUserCircleAvatar extends StatelessWidget {
     );
   }
 
-  /// Adds sizing information to [photoUrl], inserted as the last path segment
-  /// before the image filename. The format is described in [sizeDirective].
-  ///
-  /// Falls back to the default profile photo if [photoUrl] is [null].
-  static String _sizedProfileImageUrl(String photoUrl, double size) {
-    if (photoUrl == null) {
-      // If the user has no profile photo and no display name, fall back to
-      // the default profile photo as a last resort.
-      return 'https://lh3.googleusercontent.com/a/default-user=s${size.round()}-c';
-    }
-    final Uri profileUri = Uri.parse(photoUrl);
-    final List<String> pathSegments =
-        List<String>.from(profileUri.pathSegments);
-    if (pathSegments.length <= 2) {
-      // New style URLs
-      pathSegments.last = '${pathSegments.last}=s${size.round()}-c';
-    } else {
-      // Old style URLs
-      pathSegments
-        ..removeWhere(sizeDirective.hasMatch)
-        ..insert(pathSegments.length - 1, 's${size.round()}-c');
-    }
-    return Uri(
-      scheme: profileUri.scheme,
-      host: profileUri.host,
-      pathSegments: pathSegments,
-    ).toString();
-  }
-
   Widget _buildClippedImage(BuildContext context, BoxConstraints constraints) {
     assert(constraints.maxWidth == constraints.maxHeight);
 
@@ -123,7 +95,7 @@ class GoogleUserCircleAvatar extends StatelessWidget {
     // Add a sizing directive to the profile photo URL.
     final double size =
         MediaQuery.of(context).devicePixelRatio * constraints.maxWidth;
-    final String sizedPhotoUrl = _sizedProfileImageUrl(photoUrl, size);
+    final String sizedPhotoUrl = fife.sizedProfileImageUrl(photoUrl, size);
 
     // Fade the photo in over the top of the placeholder.
     return SizedBox(

packages/google_sign_in/test/fife.dart

@@ -0,0 +1,66 @@
+// Copyright 2019 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:google_sign_in/src/fife.dart';
+
+void main() {
+  group('sizedProfileImageUrl', () {
+    const double size = 20;
+
+    group('Old style URLs', () {
+      const String base =
+          'https://lh3.googleusercontent.com/-ukEAtRyRhw8/AAAAAAAAAAI/AAAAAAAAAAA/ACHi3rfhID9XACtdb9q_xK43VSXQvBV11Q.CMID';
+      const String expected = '$base/s20-c/photo.jpg';
+
+      test('with directives, sets size', () {
+        final String url = '$base/s64-c/photo.jpg';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('no directives, sets size and crop', () {
+        final String url = '$base/photo.jpg';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('no crop, sets size and crop', () {
+        final String url = '$base/s64/photo.jpg';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+    });
+
+    group('New style URLs', () {
+      const String base =
+          'https://lh3.googleusercontent.com/a-/AAuE7mC0Lh4F4uDtEaY7hpe-GIsbDpqfMZ3_2UhBQ8Qk';
+      const String expected = '$base=c-s20';
+
+      test('with directives, sets size', () {
+        final String url = '$base=s120-c';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('no directives, sets size and crop', () {
+        final String url = base;
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('no directives, but with an equals sign, sets size and crop', () {
+        final String url = '$base=';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('no crop, adds crop', () {
+        final String url = '$base=s120';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+
+      test('many directives, sets size and crop, preserves other directives',
+          () {
+        final String url = '$base=s120-c-fSoften=1,50,0';
+        final String expected = '$base=c-fSoften=1,50,0-s20';
+        expect(sizedProfileImageUrl(url, size), expected);
+      });
+    });
+  });
+}