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src/site/codelabs/darrrt/examples/6-piratebadge_json/piratebadge.dart

Index: src/site/codelabs/darrrt/examples/6-piratebadge_json/piratebadge.dart
diff --git a/src/site/codelabs/darrrt/examples/6-piratebadge_json/piratebadge.dart b/src/site/codelabs/darrrt/examples/6-piratebadge_json/piratebadge.dart
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+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+
+// Demonstrates:
+// list, maps, random, strings, string interpolation
+// cascade, fat arrow, ternary operator
+// named constructors
+// optional parameters
+// a class
+// getters
+// httprequest, JSON
+// local storage
+// static class-level methods/fields
+// top-level variables and functions
+// typecasting with 'as'
+// futures
+// import, also with show
+// dart:core, html, math, convert and async libraries
+
+import 'dart:html';
+import 'dart:math' show Random;
+import 'dart:convert' show JSON;
+import 'dart:async' show Future;
+
+final String TREASURE_KEY = 'pirateName';
+
+ButtonElement genButton;
+SpanElement badgeNameElement;
+
+void  main() {
+  InputElement inputField = querySelector('#inputName');
+  inputField.onInput.listen(updateBadge);
+  genButton = querySelector('#generateButton');
+  genButton.onClick.listen(generateBadge);
+  
+  badgeNameElement = querySelector('#badgeName');
+  
+  PirateName.readyThePirates()
+    .then((_) {
+      //on success
+      inputField.disabled = false; //enable
+      genButton.disabled = false;  //enable
+      setBadgeName(getBadgeNameFromStorage());
+    })
+    .catchError((arrr) {
+      print('Error initializing pirate names: $arrr');
+      badgeNameElement.text = 'Arrr! No names.';
+    });
+}
+
+void updateBadge(Event e) {
+  String inputName = (e.target as InputElement).value;
+  
+  setBadgeName(new PirateName(firstName: inputName));
+  if (inputName.trim().isEmpty) {
+    genButton..disabled = false
+             ..text = 'Aye! Gimme a name!';
+  } else {
+    genButton..disabled = true
+             ..text = 'Arrr! Write yer name!';
+  }
+}
+
+void generateBadge(Event e) {
+  setBadgeName(new PirateName());
+}
+
+void setBadgeName(PirateName newName) {
+  if (newName == null) {
+    return;
+  }
+  badgeNameElement.text = newName.pirateName;
+  window.localStorage[TREASURE_KEY] = newName.jsonString;
+}
+
+PirateName getBadgeNameFromStorage() {
+  String storedName = window.localStorage[TREASURE_KEY];
+  if (storedName != null) {
+    return new PirateName.fromJSON(storedName);
+  } else {
+    return null;
+  }
+}
+
+/* 
+ * A class declaration.
+ */
+class PirateName {
+  
+  // static variables are shared by all instances.
+  // Random is a random number generator in dart:math.
+  static final Random indexGen = new Random();
+
+  // List is a parameterized type. You can declare the type of the objects it contains.
+  static List<String> names = [];
+  static List<String> appellations = [];
+
+  // Instance variables. Private variables have names that start with underscore '_'.
+  String _firstName;
+  String _appellation;
+  
+  // A constructor with two optional, named parameters.
+  PirateName({String firstName, String appellation}) {
+    
+    // Use nextInt to get a random integer from a Random object.
+    // Use length to get the number of items in a list.
+    if (firstName == null) {
+      _firstName = names[indexGen.nextInt(names.length)];
+    } else {
+      _firstName = firstName;
+    }
+    if (appellation == null) {
+      _appellation = appellations[indexGen.nextInt(appellations.length)];
+    } else {
+      _appellation = appellation;
+    }
+  }
+
+  // A named constructor.
+  PirateName.fromJSON(String jsonString) {
+    // JSON is the default implementation of a JSON encoder/decoder.
+    // Map is a collection of key-value pairs.
+    Map storedName = JSON.decode(jsonString);
+    _firstName = storedName['f'];
+    _appellation = storedName['a'];
+  }
+
+  // Fat arrow syntax is shorthand for a one-line function that returns a value.
+  String toString() => pirateName;
+
+  // A getter provides read access to the member of an object.
+  String get jsonString => '{ "f": "$_firstName", "a": "$_appellation" } ';
+
+  // The ternary operator is shorthand for if-then-else. 
+  // String interpolation lets you easily build strings from other objects.
+  String get pirateName => _firstName.isEmpty ? '' : '$_firstName the $_appellation';
+
+  static Future readyThePirates() {
+    String path = 'piratenames.json';
+    return HttpRequest.getString(path)
+        .then(_parsePirateNamesFromJSON);
+  }
+  
+  static _parsePirateNamesFromJSON(String jsonString) {
+    Map pirateNames = JSON.decode(jsonString);
+    names = pirateNames['names'];
+    appellations = pirateNames['appellations'];
+  }
+}