Make Fitness tiles nicer

Moved from Cards to Tiles and made the printing
of the dates nicer by using some code from a Dart SDK example:
https://github.com/dart-lang/sdk/blob/master/samples-dev/swarm/swarm_ui_lib/util/DateUtils.dart

I also built a UserData class to help keep saving/sorting
consistent as well as fixed the sort order to have most
recent at the top.

@abarth

examples/fitness/lib/date_utils.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.
+
+// Forked from https://github.com/dart-lang/sdk/blob/master/samples-dev/swarm/swarm_ui_lib/util/DateUtils.dart
+class DateUtils {
+
+  static const WEEKDAYS = const ['Monday', 'Tuesday', 'Wednesday', 'Thursday',
+                                 'Friday', 'Saturday', 'Sunday'];
+
+  static const YESTERDAY = 'Yesterday';
+
+  static const MS_IN_WEEK =
+        DateTime.DAYS_PER_WEEK * Duration.MILLISECONDS_PER_DAY;
+
+  /** Formats a time in H:MM A format */
+  static String toHourMinutesString(Duration duration) {
+    assert(duration.inDays == 0);
+    int hours = duration.inHours;
+    String a;
+    if (hours >= 12) {
+      a = 'pm';
+      if (hours != 12) {
+        hours -= 12;
+      }
+    } else {
+      a = 'am';
+      if (hours == 0) {
+        hours += 12;
+      }
+    }
+    String twoDigits(int n) {
+      if (n >= 10) return "${n}";
+      return "0${n}";
+    }
+    String mm =
+        twoDigits(duration.inMinutes.remainder(Duration.MINUTES_PER_HOUR));
+    return "${hours}:${mm} ${a}";
+  }
+
+  /**
+   * A date/time formatter that takes into account the current date/time:
+   *  - if it's from today, just show the time
+   *  - if it's from yesterday, just show 'Yesterday'
+   *  - if it's from the same week, just show the weekday
+   *  - otherwise, show just the date
+   */
+  static String toRecentTimeString(DateTime then) {
+    bool datesAreEqual(DateTime d1, DateTime d2) {
+      return (d1.year == d2.year) && (d1.month == d2.month) &&
+          (d1.day == d2.day);
+    }
+
+    final now = new DateTime.now();
+    if (datesAreEqual(then, now)) {
+      return toHourMinutesString(new Duration(
+          days: 0,
+          hours: then.hour,
+          minutes: then.minute,
+          seconds: then.second,
+          milliseconds: then.millisecond));
+    }
+
+    final today = new DateTime(now.year, now.month, now.day, 0, 0, 0, 0);
+    Duration delta = today.difference(then);
+    if (delta.inMilliseconds < Duration.MILLISECONDS_PER_DAY) {
+      return YESTERDAY;
+    } else if (delta.inMilliseconds < MS_IN_WEEK) {
+      return WEEKDAYS[then.weekday];
+    } else {
+      // TODO(jmesserly): locale specific date format
+      String twoDigits(int n) {
+        if (n >= 10) return "${n}";
+        return "0${n}";
+      }
+      String twoDigitMonth = twoDigits(then.month);
+      String twoDigitDay = twoDigits(then.day);
+      return "${then.year}-${twoDigitMonth}-${twoDigitDay}";
+    }
+  }
+}

examples/fitness/lib/fitness_item.dart

@@ -6,7 +6,9 @@ part of fitness;
 
 typedef void FitnessItemHandler(FitnessItem item);
 
-const double kFitnessItemHeight = 79.0;
+// TODO(eseidel): This should be a constant on a SingleLineTile class
+// https://www.google.com/design/spec/components/lists.html#lists-specs
+const double kFitnessItemHeight = 48.0;
 
 abstract class FitnessItem {
   FitnessItem.fromJson(Map json) : when = DateTime.parse(json['when']);
@@ -19,7 +21,7 @@ abstract class FitnessItem {
   Map toJson() => { 'when' : when.toIso8601String() };
 
   // TODO(jackson): Internationalize
-  String get displayDate => "${when.year.toString()}-${when.month.toString().padLeft(2,'0')}-${when.day.toString().padLeft(2,'0')}";
+  String get displayDate => DateUtils.toRecentTimeString(when);
 
   FitnessItemRow toRow({ FitnessItemHandler onDismissed });
 }
@@ -40,12 +42,19 @@ abstract class FitnessItemRow extends Component {
   Widget build() {
     return new Dismissable(
       onDismissed: () => onDismissed(item),
-      child: new Card(
-        child: new Container(
-          height: kFitnessItemHeight,
-          padding: const EdgeDims.all(8.0),
-          child: buildContent()
-        )
+      child: new Container(
+        height: kFitnessItemHeight,
+        // TODO(eseidel): Padding top should be 16px for a single-line tile:
+        // https://www.google.com/design/spec/components/lists.html#lists-specs
+        padding: const EdgeDims.all(10.0),
+        // TODO(eseidel): This line should be drawn by the list as it should
+        // stay put even when the tile is dismissed!
+        decoration: new BoxDecoration(
+          border: new Border(
+            bottom: new BorderSide(color: Theme.of(this).dividerColor)
+          )
+        ),
+        child: buildContent()
       )
     );
   }

examples/fitness/lib/main.dart

@@ -9,6 +9,8 @@ import 'package:sky/painting/text_style.dart';
 import 'package:sky/theme/colors.dart' as colors;
 import 'package:sky/widgets.dart';
 import 'user_data.dart';
+import 'date_utils.dart';
+import 'dart:async';
 
 part 'feed.dart';
 part 'fitness_item.dart';
@@ -17,23 +19,47 @@ part 'meal.dart';
 part 'measurement.dart';
 part 'settings.dart';
 
-class FitnessApp extends App {
+class UserData {
+  List<FitnessItem> _items = [];
+
+  List<FitnessItem> get items => _items;
+  void set items(List<FitnessItem> newItems) {
+    _items = [];
+    _items.addAll(newItems);
+    sort();
+  }
+
+  void sort() {
+    _items.sort((a, b) => -a.when.compareTo(b.when));
+  }
+
+  void addAndSave(FitnessItem item) {
+    _items.add(item);
+    sort();
+    save();
+  }
+
+  void removeAndSave(FitnessItem item) {
+    _items.remove(item);
+    save();
+  }
+
+  Future save() => saveFitnessData(_items);
+}
 
+class FitnessApp extends App {
   NavigationState _navigationState;
-  final List<FitnessItem> _userData = [];
+  final UserData _userData = new UserData();
 
   void didMount() {
     super.didMount();
     loadFitnessData().then((List<Measurement> list) {
-      setState(() {
-        _userData.addAll(list);
-      });
+      setState(() => _userData.items = list);
     }).catchError((e) => print("Failed to load data: $e"));
   }
 
   void save() {
-    saveFitnessData(_userData)
-      .catchError((e) => print("Failed to load data: $e"));
+    _userData.save().catchError((e) => print("Failed to load data: $e"));
   }
 
   void initState() {
@@ -42,7 +68,7 @@ class FitnessApp extends App {
         name: '/',
         builder: (navigator, route) => new FeedFragment(
           navigator: navigator,
-          userData: _userData,
+          userData: _userData.items,
           onItemCreated: _handleItemCreated,
           onItemDeleted: _handleItemDeleted
         )
@@ -71,27 +97,18 @@ class FitnessApp extends App {
 
   void onBack() {
     if (_navigationState.hasPrevious()) {
-      setState(() {
-        _navigationState.pop();
-      });
+      setState(() => _navigationState.pop());
     } else {
       super.onBack();
     }
   }
 
   void _handleItemCreated(FitnessItem item) {
-    setState(() {
-      _userData.add(item);
-      _userData.sort((a, b) => a.when.compareTo(b.when));
-      save();
-    });
+    setState(() => _userData.addAndSave(item));
   }
 
   void _handleItemDeleted(FitnessItem item) {
-    setState(() {
-      _userData.remove(item);
-      saveFitnessData(_userData);
-    });
+    setState(() => _userData.removeAndSave(item));
   }
 
   BackupMode backupSetting = BackupMode.disabled;

examples/fitness/lib/measurement.dart

@@ -35,7 +35,7 @@ class MeasurementRow extends FitnessItemRow {
       new Flexible(
         child: new Text(
           measurement.displayWeight,
-          style: const TextStyle(textAlign: TextAlign.right)
+          style: Theme.of(this).text.subhead
         )
       ),
       new Flexible(