Refactoring to support dark theme better

sky/sdk/lib/theme/theme_data.dart

 // Copyright 2015 The Chromium 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 'dart:sky';
 
 import 'typography.dart' as typography;
 import 'colors.dart' as colors;
 
 enum ThemeBrightness { dark, light }
 
 class ThemeData {
 
-  ThemeData.light({
-    this.primary,
-    this.accent,
-    bool darkToolbar: false })
-    : brightness = ThemeBrightness.light,
-      toolbarText = darkToolbar ? typography.white : typography.black,
-      text = typography.black;
+  ThemeData({
+    ThemeBrightness brightness,
+    Map<int, Color> primarySwatch,
+    Color accentColor,
+    Color floatingActionButtonColor,
+    typography.TextTheme text,
+    typography.TextTheme toolbarText })
+    : this.brightness = brightness,
+      this.primarySwatch = primarySwatch,
+      canvasColor = brightness == ThemeBrightness.dark ? colors.Grey[850] : colors.Grey[50],
+      cardColor = brightness == ThemeBrightness.dark ? colors.Grey[800] : colors.White,
+      text = brightness == ThemeBrightness.dark ? typography.white : typography.black {
+    assert(brightness != null);
 
-  ThemeData.dark({ this.primary, this.accent })
-    : brightness = ThemeBrightness.dark,
-      toolbarText = typography.white,
-      text = typography.white;
+    if (primarySwatch == null) {
+      _primaryColor = brightness == ThemeBrightness.dark ? colors.Grey[900] : colors.Grey[100];
+    } else {
+      _primaryColor = primarySwatch[500];
+    }
 
-  ThemeData.fallback()
-    : brightness = ThemeBrightness.light,
-      primary = colors.Indigo,
-      accent = colors.PinkAccent,
-      toolbarText = typography.white,
-      text = typography.black;
+    if (accentColor == null) {
+      _accentColor = primarySwatch == null ? colors.Blue[500] : primarySwatch[500];
+    } else {
+      _accentColor = accentColor;
+    }
+
+    if (floatingActionButtonColor == null) {
+      _floatingActionButtonColor = accentColor == null ? colors.PinkAccent[200] : accentColor;
+    } else {
+      _floatingActionButtonColor = floatingActionButtonColor;
+    }
+
+    if (toolbarText == null) {
+      if (colors.DarkColors.contains(primarySwatch) || _primaryColor == colors.Grey[900])
+        _toolbarText = typography.white;
+      else
+        _toolbarText = typography.black;
+    } else {
+      _toolbarText = toolbarText;
+    }
+  }
+
+  factory ThemeData.light() => new ThemeData(primarySwatch: colors.Blue, brightness: ThemeBrightness.light);
+  factory ThemeData.dark() => new ThemeData(brightness: ThemeBrightness.dark);
+  factory ThemeData.fallback() => new ThemeData.light();
 
   final ThemeBrightness brightness;
-  final Map<int, Color> primary;
-  final Map<int, Color> accent;
+  final Map<int, Color> primarySwatch;
+  final Color canvasColor;
+  final Color cardColor;
   final typography.TextTheme text;
-  final typography.TextTheme toolbarText;
+
+  Color _primaryColor;
+  Color get primaryColor => _primaryColor;
+
+  Color _accentColor;
+  Color get accentColor => _accentColor;
+
+  Color _floatingActionButtonColor;
+  Color get floatingActionButtonColor => _floatingActionButtonColor;
+
+  typography.TextTheme _toolbarText;
+  typography.TextTheme get toolbarText => _toolbarText;
 }