created library

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Dart & Flutter",
+            "request": "launch",
+            "type": "dart"
+        }
+    ]
+}

Book.dart

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+class Book{
+
+  late String bookTitle;
+  late String bookAuthorName;
+  late String category;
+  late int availableCopies;
+  late int price;
+
+  Book(String bookTitle, String bookAuthorName, 
+    String category, int availableCopies, int price){
+
+      this.bookTitle = bookTitle;
+      this.bookAuthorName = bookAuthorName;
+      this.category = category;
+      this.availableCopies = availableCopies;
+      this.price = price;   
+  }
+
+  addBook (){
+
+    availableCopies ++;
+  }
+
+  removeBook (){
+
+    availableCopies--;
+  }
+
+  @override
+  String toString() {
+
+    String bookAsString = "Book title - $bookTitle   Author- $bookAuthorName  Price- $price";
+
+    return bookAsString;
+  }
+
+}

main.dart

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+import 'dart:io';
+import 'Book.dart';
+
+List<Book> library = [];
+
+main (){
+showMainMenu();
+
+}
+
+showMainMenu(){
+
+  starsLine();
+  print("1. Query a book");
+  print("2. Add a book");
+  print("3. Delete a book");
+  print("4. Update a book");
+  print("5. Make a purchase");
+  starsLine();
+  print("Please select an option:");
+
+  int? choice = int.parse(stdin.readLineSync()!);
+
+  switch(choice){
+    case 1:
+      findABookMenu();
+    break;
+    case 2:
+      addBook();
+    break;
+    case 3:
+      deleteBook();
+    break;
+    case 4:
+      updateBook();
+    break;
+    case 5:
+      purchaseBooks();
+    break;
+    default: { 
+
+      invaildOption();
+   }
+   break; 
+  }
+}
+
+findABookMenu() {
+
+  starsLine();
+  print("How do you want to find the book:");
+  print("1. Using it's title.");
+  print("2. Using the author name.");
+  print("3. Using the category of the book.");
+  starsLine();
+
+  print("Select an option:");
+  int optionFind = int.parse(stdin.readLineSync()!);
+
+
+  print("Please enter the search term:");
+  String? searchTerm = stdin.readLineSync();
+  if (searchTerm == null || searchTerm.isEmpty) {
+    invaildOption();
+    return;
+  }
+
+  Book? book;
+  switch(optionFind){
+    case 1:
+      book = findBook(searchTerm, "title");
+      print(book.toString());
+    break;
+    case 2:
+      book = findBook(searchTerm, "author");
+      print(book.toString());
+    break;
+    case 3:
+      book = findBook(searchTerm, "category");
+      print(book.toString());
+    break;
+    default: { 
+      invaildOption();
+   }
+   break;
+  }
+
+  starsLine();
+  print("To look for another book press [Y], otherwise return to main menu:");
+
+  if(stdin.readLineSync() == "Y"){
+
+    findABookMenu();
+  } else{
+
+    showMainMenu();
+  }
+
+
+}
+
+Book? findBook(String searchTerm, String searchAttribute) {
+
+  Book? targetBook = null;
+  String bookSearchData;
+
+  library.forEach((book) {
+
+    if (searchAttribute == "title"){
+      bookSearchData = book.bookTitle;
+    } else if(searchAttribute == "author"){
+      bookSearchData = book.bookAuthorName;
+    } else {
+      bookSearchData = book.category;
+    }
+
+    if (bookSearchData == searchTerm){
+      targetBook = book;
+    }
+  });
+
+  return targetBook;
+}
+
+addBook(){
+
+  starsLine();
+  print("Please enter the book title:");
+  String title = stdin.readLineSync() ?? "";
+
+  print("Please enter the book author:");
+  String author = stdin.readLineSync() ?? "";
+
+  print("Category of the book:");
+  String category = stdin.readLineSync() ?? "";
+
+  print("Number of copies to be added:");
+  int numberOfCopies =  int.parse(stdin.readLineSync() ?? "");
+
+  print("The price of the book:");
+  int price =  int.parse(stdin.readLineSync() ?? "");
+
+  library.add(Book(title, author, category, numberOfCopies, price));
+
+  starsLine();
+  print("Book was added successfully");
+  starsLine();
+  showMainMenu();
+
+}
+
+deleteBook(){
+
+  starsLine();
+  print("Enter book title:");
+  String? bookTitle = stdin.readLineSync();
+  if (bookTitle == null || bookTitle.isEmpty) {
+    invaildOption();
+    return;
+  }
+
+  library.remove(findBook(bookTitle, "title"));
+  print("Book was removed successfully");
+  showMainMenu();
+
+}
+
+updateBook(){
+  starsLine();
+  print("Enter book title:");
+  String? bookTitle = stdin.readLineSync();
+  if (bookTitle == null || bookTitle.isEmpty) {
+    invaildOption();
+    return;
+  }
+
+  Book? book = findBook(bookTitle, "title");
+
+  print("Which data do you want to update:");
+  print("1. Title");
+  print("2. Author");
+  print("3. Category");
+  print("4. Number of copies");
+  print("5. Price");
+
+  print("Select an option:");
+  int optionFind = int.parse(stdin.readLineSync()!);
+
+  print("Input new value:");
+  String? newValue = stdin.readLineSync();
+  if (newValue == null || newValue.isEmpty) {
+    invaildOption();
+    return;
+  }
+
+  switch(optionFind){
+    case 1:
+      book!.bookTitle = newValue;
+    break;
+    case 2:
+      book!.bookAuthorName = newValue;
+    break;
+    case 3:
+      book!.category = newValue;
+    break;
+    case 4:
+      book!.availableCopies = int.parse(newValue);
+    break;
+    case 5:
+      book!.price = int.parse(newValue);
+    break;
+  }
+
+   print("Book was updated successfully");
+  showMainMenu();
+
+}
+
+purchaseBooks(){
+
+  List<Book> books = [];
+
+  do {
+  starsLine();
+  print("Enter book title:");
+  String? bookTitle = stdin.readLineSync();
+  if (bookTitle == null || bookTitle.isEmpty) {
+    invaildOption();
+    return;
+  }
+
+  books.add(findBook(bookTitle, "title")!);
+
+  starsLine();
+  print("To look for another book press [Y], otherwise checkout:");
+
+  } while(stdin.readLineSync() == "Y");
+
+  checkout(books);
+}
+
+checkout(List<Book> books){
+
+  int totalCost = 0;
+  books.forEach((book) { 
+
+    print(book.toString());
+    totalCost = totalCost + book.price;
+    book.availableCopies--;
+  });
+
+  starsLine();
+  print("Total cost: $totalCost");
+  showMainMenu();
+}
+
+starsLine(){
+
+  print("*******************************");
+}
+
+invaildOption(){
+
+  print("Please enter a vaild option!");
+  showMainMenu();
+}