main.dart

import 'package:flutter/material.dart';
import 'package:english_words/english_words.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Startup Name Generator',
        home: RandomWords(),
        theme: ThemeData(
          primaryColor: Colors.white,
        ));
  }
}

class RandomWordsState extends State<RandomWords> {
  final List<WordPair> _suggestions = <WordPair>[];
  final TextStyle _biggerfont = const TextStyle(fontSize: 18.0);
  final Set<WordPair> _saved = Set<WordPair>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text('Startup Name Generator'),
          actions: <Widget>[
            IconButton(icon: Icon(Icons.list), onPressed: _pushSaved)
          ],
        ),
        body: _buildSuggestions());
  }

  void _pushSaved() {
    Navigator.of(context).push(
      MaterialPageRoute<void>(
        // Add 20 lines from here...
        builder: (BuildContext context) {
          final Iterable<ListTile> tiles = _saved.map(
            (WordPair pair) {
              return ListTile(
                title: Text(
                  pair.asPascalCase,
                  style: _biggerfont,
                ),
              );
            },
          );
          final List<Widget> divided = ListTile.divideTiles(
            context: context,
            tiles: tiles,
          ).toList();

          return Scaffold(
            appBar: AppBar(
              title: Text('Saved Suggestions'),
            ),
            body: ListView(children: divided),
          );
        },
      ),
    );
  }

  Widget _buildSuggestions() {
    return ListView.builder(
      padding: const EdgeInsets.all(16.0),
      itemBuilder: (context, i) {
        if (i.isOdd) return Divider();

        final index = i ~/ 2;

        if (index >= _suggestions.length) {
          _suggestions.addAll(generateWordPairs().take(10));
        }

        return _buildRow(_suggestions[index]);
      },
    );
  }

  Widget _buildRow(WordPair pair) {
    final bool alreadySaved = _saved.contains(pair);

    return ListTile(
      title: Text(pair.asPascalCase, style: _biggerfont),
      trailing: Icon(alreadySaved ? Icons.favorite : Icons.favorite_border,
          color: alreadySaved ? Colors.red : null),
      onTap: () {
        setState(() {
          if (alreadySaved) {
            _saved.remove(pair);
          } else {
            _saved.add(pair);
          }
        });
      },
    );
  }
}

class RandomWords extends StatefulWidget {
  @override
  RandomWordsState createState() => RandomWordsState();
}