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lib/13/go/books/src/data/library.dart

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+// Copyright 2013 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 'author.dart';
+import 'book.dart';
+
+/// Library data mock.
+final Library libraryInstance = Library()
+  ..addBook(
+      title: 'Left Hand of Darkness',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: true,
+      isNew: true)
+  ..addBook(
+      title: 'Too Like the Lightning',
+      authorName: 'Ada Palmer',
+      isPopular: false,
+      isNew: true)
+  ..addBook(
+      title: 'Kindred',
+      authorName: 'Octavia E. Butler',
+      isPopular: true,
+      isNew: false)
+  ..addBook(
+      title: 'The Lathe of Heaven',
+      authorName: 'Ursula K. Le Guin',
+      isPopular: false,
+      isNew: false);
+
+/// A library that contains books and authors.
+class Library {
+  /// The books in the library.
+  final List<Book> allBooks = <Book>[];
+
+  /// The authors in the library.
+  final List<Author> allAuthors = <Author>[];
+
+  /// Adds a book into the library.
+  void addBook({
+    required String title,
+    required String authorName,
+    required bool isPopular,
+    required bool isNew,
+  }) {
+    final Author author = allAuthors.firstWhere(
+      (Author author) => author.name == authorName,
+      orElse: () {
+        final Author value = Author(id: allAuthors.length, name: authorName);
+        allAuthors.add(value);
+        return value;
+      },
+    );
+
+    final Book book = Book(
+      id: allBooks.length,
+      title: title,
+      isPopular: isPopular,
+      isNew: isNew,
+      author: author,
+    );
+
+    author.books.add(book);
+    allBooks.add(book);
+  }
+
+  /// The list of popular books in the library.
+  List<Book> get popularBooks => <Book>[
+        ...allBooks.where((Book book) => book.isPopular),
+      ];
+
+  /// The list of new books in the library.
+  List<Book> get newBooks => <Book>[
+        ...allBooks.where((Book book) => book.isNew),
+      ];
+}