LU07.L01 - Bibliothek

""" Provides the class Customer for the Library application."""
 
 
class Customer:
    """
    Defines a customer of our library who,
    * borrows [ borrow_book_by_title() ] or
    * returns [ bring_back_book() ]
    a book.
    Each customer may only borrow one book at a time.
 
    Attributes
    ----------
    name: str
        The full name of this customer.
    reminded: bool (Default: false)
        Has this customer been reminded to return an overdue book.
    librarian: Librarian
        A reference to a librarian of our library.
    book: Book (Default: None)
        The book currently borrowed by this customer. None=no book borrowed
    """
 
    def __init__(self, name, librarian, library):
        """
        Creates a customer object, sets the reference to the librarian
        and registers the client with the library.
        :param name: Full name of this customer.
        :param librarian: A reference to the librarian.
        :param library: A reference to the library.
        """
        self._name = name
        self._reminded = False
        self._librarian = librarian
        self._book = None
        library.add_customer(self)
 
    def __str__(self):
        """
        Gibt den Namen des Kunden aus.
        """
        return f'Kunde: {self.name}'
 
    def borrow_book_by_title(self, title):
        """
        Borrows a book identified by the title from the librarian.
        If the book is available, the reference to the book will be set.
        Otherwise, an error message is printed.
 
        :param title: The title of the book.
        """
        self._book = self._librarian.lend_book_by_title(title)
        if self._book is not None:
            print(f'{self.name} hat das Buch "{self.book.title}" erhalten.')
 
    def bring_back_book(self):
        """
        Returns the book to the librarian.
        The reference to the book will be set to None.
        """
        print(f'{self.name} hat das Buch "{self.book.title}" zurückgebracht')
        self._librarian.take_back_book(self._book)
        self._book = None
 
    @property
    def name(self):
        """
        Gets the name of this customer.
        :return: Name des Kunden
        """
        return self._name
 
    @property
    def book(self):
        """
        Gets the name of the borrowed book.
        :return: Referenz zum ausgeliehenen Buch
        """
        return self._book
 
    @property
    def reminded(self):
        """
        Gets the status of the reminder.
        :return: Status der Mahnung true/false
        """
        return self._reminded
 
    @reminded.setter
    def reminded(self, value):
        """
        Sets the status of the reminder.
        """
        self._reminded = value

""" Provides the class Librarian for the Library application."""
from book import Book
from library import Library
 
 
class Librarian:
    """
    Defines the librarian, who:
 
    * buys new books, buy_new_book(...)
    * lends books to the customer, lend_book_by_title(...)
    * takes back the books, take_back_book(...)
    * remindes overdue customers, remind_customer(...)
    * removes books from the library, remove_book(...)
 
    Attributes
    ----------
    name: str
        The full name of the librarian.
    library: Library
        A reference to the library this librarian works for.
 
    """
 
    def __init__(self, name, library):
        """
        Creates the librarian-object with his name
        and a reference to the library.
        :param name: The full name of this librarian.
        :param library: A reference to the library.
        """
        self._name = name
        self._library = library
 
    def buy_new_book(self, title, isbn):
        """
        Creates a new book with the title and ISBN-number to the library.
        Adds this book to the library and saves the location (shelf).
        :param title: The title of the new book.
        :param isbn:  The ISBN-number of the new book.
        """
        book = Book(title, isbn)
        book.location = self._library.add_book(book)
 
    def lend_book_by_title(self, title):
        """
        Lends the book with the specified title to a customer.
        If no book with this title is available, it prints a message.
        :param title: The title of the requested book.
        :return: book-object or None=not dound
        """
        book = self._library.search_book_by_title(title)
        if book is None:
            print('Das angefragte Buch ist nicht vorhanden')
        else:
            location = book.location
            book = self._library.lend_book(location)
        return book
 
    def take_back_book(self, borrowed_book):
        """
        Takes back a book and returns it to the library.
        :param borrowed_book: The book given back by the customer.
        """
        self._library.reshelve_book(borrowed_book)
 
    def remove_book(self, title):
        """
        Removes the book with the specified title from the library.
        :param title: The title of the book to be removed
        :raise: LookupError when there is no book with the specified title.
        """
        print(f'\n---\nentferne Buch "{title}"')
        book = self._library.search_book_by_title(title)
        self._library.remove_book(book)
 
    def remind_customer(self, name):
        """
        Reminds a customer, that a book is overdue.
        :param name: The name of the customer to be reminded.
        """
        customer = self._library.search_customer(name)
        customer.reminded = True
        print(f'Erinnerung für {name}: Dein Buch ist überfällig')