LibraryManagementSystem.py

import getpass
from datetime import date

# -----------------------------------
# DATA STORAGE
# -----------------------------------

books = []
borrowing_records = []

USERS_FILE = "passwords.txt"

def load_users():
    """Load users from passwords.txt"""
    users = {}
    try:
        with open(USERS_FILE) as f:
            for line in f:
                username, password, role = line.strip().split(",")
                users[username] = {"password": password, "role": role}
    except FileNotFoundError:
        pass
    return users

def authenticate(username, password):
    users = load_users()
    if username not in users:
        return None, "User does not exist"

    if password != users[username]["password"]:
        return None, "Incorrect password"

    return users[username]["role"], "Login successful!"

# -----------------------------------
# VALIDATION & UTILITY
# -----------------------------------

def validate_isbn(isbn):
    """ISBN must be numeric and 10 or 13 digits. """
    return isbn.isdigit() and len(isbn) in (10, 13)

def calculate_late_fee(days_overdue):
    """Calculate late fee based on given fee structure"""
    if days_overdue <= 0:
        return 0.0
    if days_overdue <= 7:
        returnmin(days_overdue * 0.5, 3.5)
    elif days_overdue <= 14:
        return min(3.5 + (days_overdue - 7) * 1.0, 10.5)
    elif days_overdue <= 30:
        return min(10.5 + (days_overdue - 14) * 2.0, 42.5)
    else:
        return round(42.5 + (days_overdue - 30) * 3.0, 2)

# -----------------------------------
# BOOK MANAGEMENT (ADMIN)
# -----------------------------------

def add_book(title, isbn, author, category):
    if not title.strip() or not author.strip():
        return "Error: Title and author cannot be empty"

    if not validate_isbn(isbn):
        return "Error: ISBN is not a valid ISBN"

    for book in books:
        if book["isbn"] == isbn:
            return "Error: ISBN already exists"

    books.append({"title": title, "isbn": isbn, "author": author, "category": category, "available": True, "borrow_count": 0})
    return "Book added successfully!"

def search_book(search_term, search_type):
    results = []
    for book in books:
        if search_type == "title" and search_term.lower() in book["title"].lower():
            results.append(book)
        elif search_type == "author" and search_term.lower() in book["author"].lower():
            results.append(book)
        elif search_type == "isbn" and search_term == book["isbn"]:
            results.append(book)
    return results

# -----------------------------------
# BORROWING MANAGEMENT (USER)
# -----------------------------------

def borrow_book(member_id, isbn):
    for book in books:
        if book["isbn"] == isbn:
            if not book["available"]:
                return "Error: Book is not available"

            book["available"] = False
            book["borrow_count"] += 1

            borrowing_records.append({
                "member_id": member_id,
                "isbn": isbn,
                "borrow_date": date.today(),
                "return_date": None,
                "late_fee": 0.0
            })
            return "Book borrowed successfully!"

    return "Error: Book not found"

def return_book(member_id, isbn):
    for record in borrowing_records:
        if record["member_id"] == member_id and record["isbn"] == isbn and record["return_date"] is None:
            record["return_date"] = date.today()

            days_borrowed = (record["return_date"] - record["borrow_date"]).days
            overdue_days = max(0, days_borrowed - 14)
            fee = calculate_late_fee(overdue_days)
            record["late_fee"] = fee

            for book in books:
                if book["isbn"] == isbn:
                    book["available"] = True
                    title = book["title"]

            return f"Returned '{title}'. Days borrowed: {days_borrowed}, Late fee: RM {fee}"

    return "Error: Active borrowing records not found"

def get_member_borrowing_history(member_id):
    history = []
    for record in borrowing_records:
        if record["member_id"] == member_id:
            history.append(record)
    return history

# -----------------------------------
# REPORTS (ADMIN)
# -----------------------------------

def generate_available_books_report(category=None):
    report = {}
    for book in books:
        if book["available"] and (category is None or book["category"] == category):
            report.setdefault(book["category"], []).append(book)
    return report

def generate_library_summary():
    total_books = len(books)
    available = sum(1 for b in books if b["available"])
    borrowed = total_books - available

    most_borrowed = max(books, key=lambda book: book["borrow_count"], default=None)
    total_fees = sum(r["late_fee"] for r in borrowing_records)

    overdue = [
        r for r in borrowing_records
        if r["return_date"] is None and (date.today() - r["borrow_date"]).days > 14
    ]

    category_dist = {}
    for b in books:
        category_dist[b["category"]] = category_dist.get(b["category"], 0) + 1

    return {
        "total_books": total_books,
        "available": available,
        "borrowed": borrowed,
        "most_borrowed": most_borrowed,
        "total_fees": total_fees,
        "overdue_books": overdue,
        "category_distribution": category_dist,
    }

# -----------------------------------
# MENUS
# -----------------------------------

def userMenu(username):
    while True:
        print (f"\n=== Welcome to the library system, {username}! ===")
        print ("1. Search book")
        print ("2. Borrow book")
        print ("3. Return book")
        print ("4. View borrowing history")
        print ("5. Logout")

        choice = input("Enter your choice: ")

        if choice == "1":
            st = input("Search by (title/author/ISBN): )")
            term = input("Enter search term: ")
            print(search_book(term, st))

        elif choice == "2":
            print(borrow_book(username, input("Enter book ISBN: ")))

        elif choice == "3":
            print(return_book(username, input("Enter book ISBN: ")))

        elif choice == "4":
            print(get_member_borrowing_history(username))

        elif choice == "5":
            break

        else:
            print ("Invalid choice")

def adminMenu(username):
    while True:
        print ("\n=== Admin Interface ===")
        print("1. Add book")
        print("2. View available books")
        print("3. Library Summary")
        print("4. Logout")

        choice = input("Enter your choice: ")

        if choice == "1":
            print(add_book(
                input("Title:"),
                input("ISBN:"),
                input("Author:"),
                input("Category"),
            ))

        elif choice == "2":
            print(generate_available_books_report())

        elif choice == "3":
            print(generate_library_summary())

        elif choice == "4":
            break

        else:
            print ("Invalid choice")

# -----------------------------------
# HOME
# -----------------------------------

def libraryHome():
    # Sample data
    add_book("1984", "1234567890", "George Orwell", "Fiction")
    add_book("Python Programming", "1234567890123", "John Smith", "Reference")
    add_book("Children Tales", "0987654321", "Jane Doe", "Children")
    add_book("Data Science", "9998887776661", "Alice Brown", "Non-Fiction")

    while True:
        print ("\n=== LIBRARY HOME ===")
        print ("1. Login")
        print ("2. Request user creation - Library Admin")
        print ("3. Exit")

        choice = input("Enter your choice: ")

        if choice == "1":
            username = input("Username: ")
            password = input("Password: ")

            role, msg = authenticate(username, password)
            print(msg)

            if role == "admin":
                adminMenu(username)
            elif role == "libuser":
                userMenu(username)

        elif choice == "2":
            print ("Email admin at library_admin@library.com.my")

        elif choice == "3":
            break

        else:
            print ("Invalid choice")

# -----------------------------------
# PROGRAM ENTRY
# -----------------------------------

libraryHome()