Finance.py

import math
import datetime
import os

class Financial_Calculator:
    def __init__(self):
        self.users = {}
        self.current_user = None
        self.user_info = {}

    def load_users_data(self):
        if os.path.exists("users_data.txt"):
            with open("users_data.txt", "r") as users_file:
                lines = users_file.readlines()
                for i in range(0, len(lines), 2):
                    username = lines[i].strip()
                    password = lines[i + 1].strip()
                    self.users[username] = password

    def save_users_data(self):
        with open("users_data.txt", "w") as users_file:
            for username, password in self.users.items():
                users_file.write(f"{username}\n{password}\n")

    def register_user(self):
        username = input("Enter your username: ")

        while True:
            password = input("Enter your password (at least 8 characters with one uppercase, one lowercase, and one digit): ")
            if len(password) >= 8 and any(c.isupper() for c in password) and any(c.islower() for c in password) and any(c.isdigit() for c in password):
                break
            else:
                print("Invalid password. Please make sure it is at least 8 characters long and meets the strength requirements.")

        self.users[username] = password
        print("Registration successful!")
        self.save_users_data()

    def login_user(self):
        username = input("Enter your username: ")
        password = input("Enter your password: ")
        if username in self.users and self.users[username] == password:
            self.current_user = username
            print(f"Login successful, welcome {username}!")
            self.load_user_info()
        else:
            print("Invalid username or password. Please try again.")

    def load_user_info(self):
        file_name = f"{self.current_user}_data.txt"
        if os.path.exists(file_name):
            with open(file_name, "r") as user_file:
                lines = user_file.readlines()
                for line in lines:
                    key, value = line.strip().split(": ")
                    nested_key, nested_value = value.split(", ")
                    self.user_info[key] = {nested_key: float(nested_value)}

    def save_user_info(self):
        file_name = f"{self.current_user}_data.txt"
        with open(file_name, "w") as user_file:
            for key, values in self.user_info.items():
                user_file.write(f"{key}: {', '.join([f'{k}: {v}' for k, v in values.items()])}\n")

    def log_activity(self, activity):
        timestamp = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
        with open("log.txt", "a") as log_file:
            log_file.write(f"{timestamp} - {self.current_user}: {activity}\n")

    def display_dashboard(self):
        print(f"\n===== Welcome to the Dashboard, {self.current_user}! =====")
        print("Choose an option:")
        print("1. Calculate Investment")
        print("2. Calculate Bond")
        print("3. Logout")

    def calculate_investment(self):
        p = self.get_input("How much are you depositing? R", float)
        r = self.get_input("At which interest rate percentile? ", float) / 100 / 12
        t = self.get_input("How many years are you planning to invest for? ", float)
        simp_comp = self.get_input("Choose 'Simple' or 'Compound' interest: ", str).lower()

        if simp_comp == "simple":
            total = p * (1 + r * t)
        else:
            total = p * math.pow((1 + r), t)

        print(f"Your interest earned over {t} years will be R{total - p:.2f}")
        print(f"Your total amount earned over {t} years will be R{total:.2f}")

        self.user_info["Investment"] = {"Principal": p, "Interest Rate": r, "Time": t, "Type": simp_comp}
        self.log_activity("Calculated Investment")

    def calculate_bond(self):
        p = self.get_input("What is the current value of the house? R", float)
        i = self.get_input("At which interest rate percentile? ", float) / 100 / 12 / 12
        n = self.get_input("How many months you plan to repay? ", float)

        monthly = (i * p) / (1 - (1 + i) ** (-n))
        total_repayment = monthly * n

        print(f"Your monthly repayment will be R{monthly:.2f}")
        print(f"Your total repayment will be R{total_repayment:.2f}")

        self.user_info["Bond"] = {"Principal": p, "Interest Rate": i, "Months": n}
        self.log_activity("Calculated Bond")

    def logout_user(self):
        self.log_activity("Logged Out")
        self.save_user_info()
        self.current_user = None
        print("Logout successful.")

    def get_input(self, prompt, data_type):
        while True:
            try:
                user_input = data_type(input(prompt))
                return user_input
            except ValueError:
                print("Error: Please enter the required info in the input field.")

    def financial_calculator(self):
        self.load_users_data()
        while True:
            if not self.current_user:
                print("\n===== Welcome to the Financial Calculator! =====")
                print("Choose an option:")
                print("1. Register")
                print("2. Login")
                print("3. Exit")
                choice = input()

                if choice == '1':
                    self.register_user()
                elif choice == '2':
                    self.login_user()
                elif choice == '3':
                    print("Exiting the program. Goodbye!")
                    break
                else:
                    print("Invalid choice. Please try again.")
            else:
                self.display_dashboard()
                choice = input()
                if choice == '1':
                    self.calculate_investment()
                elif choice == '2':
                    self.calculate_bond()
                elif choice == '3':
                    self.logout_user()
                else:
                    print("Invalid choice. Please try again.")

                restart = input("Do you want to restart the process? (y/n): ").lower()
                if restart == "n":
                    print("Goodbye! Have a great day fam.")
                    self.save_user_info()
                    self.save_users_data()
                    break


calculator = Financial_Calculator()
calculator.financial_calculator()