📘 Day 14: Modules - Organizing Your Business Logic

"""
Day 14: Business Logic Module

This file acts as a module containing various reusable functions
for common business calculations and validations.
"""


def calculate_roi(investment: float, profit: float) -> float:
    """Calculates the Return on Investment (ROI)."""
    if investment == 0:
        return 0
    return (profit / investment) * 100


def calculate_future_value(principal: float, rate: float, years: int) -> float:
    """Calculates the future value of an investment with annual compounding."""
    return principal * ((1 + rate) ** years)


def is_eligible_for_promotion(years_of_service: int, performance_rating: int) -> bool:
    """Checks if an employee is eligible for promotion."""
    # Rule: Must have > 3 years of service and a performance rating of 4 or 5.
    return years_of_service > 3 and performance_rating >= 4


def format_as_currency(amount: float) -> str:
    """Formats a number into a standard currency string."""
    return f"${amount:,.2f}"

"""
Finance Tools Module - Alias for business_logic module

This module provides backward compatibility for scripts that import
finance_tools instead of business_logic.
"""

from business_logic import (
    calculate_future_value,
    calculate_roi,
    format_as_currency,
    is_eligible_for_promotion,
)

__all__ = [
    "calculate_roi",
    "calculate_future_value",
    "is_eligible_for_promotion",
    "format_as_currency",
]

"""
Day 14: Using Modules to Organize Code (Refactored)

This script demonstrates how to import and use functions from
both custom-built modules and Python's built-in modules.
"""

# We are importing the functions we created in the 'business_logic.py' file.
# We use an alias 'bl' to keep our code clean and concise.
import datetime
import math

import business_logic as bl


def demonstrate_custom_module():
    """Demonstrates using functions from the custom business_logic module."""
    print("--- Using Custom Business Logic Module ---")
    investment_amount = 50000
    profit_amount = 12000
    roi = bl.calculate_roi(investment_amount, profit_amount)
    print(
        f"A project with an investment of {bl.format_as_currency(investment_amount)} and profit of {bl.format_as_currency(profit_amount)} has an ROI of {roi:.2f}%."
    )

    years = 4
    rating = 5
    is_eligible = bl.is_eligible_for_promotion(years, rating)
    print(
        f"An employee with {years} years of service and a rating of {rating} is eligible for promotion: {is_eligible}"
    )
    print("-" * 20)


def demonstrate_builtin_modules():
    """Demonstrates using Python's built-in datetime and math modules."""
    print("--- Using Built-in 'datetime' and 'math' Modules ---")
    current_datetime = datetime.datetime.now()
    print(f"Current Date and Time: {current_datetime}")
    print(f"Current Year: {current_datetime.year}")
    print()

    marketing_budget = 100000
    growth_factor = math.sqrt(marketing_budget)
    print(
        f"The growth factor for a marketing budget of {bl.format_as_currency(marketing_budget)} is {growth_factor:.2f}."
    )
    print("-" * 20)


def main():
    """Main function to demonstrate module usage."""
    demonstrate_custom_module()
    demonstrate_builtin_modules()


if __name__ == "__main__":
    main()

"""Day 14: Solutions to Exercises."""

import datetime
import math

import finance_tools as ft

# --- Exercise 1: Create a Finance Module ---
print("--- Solution to Exercise 1 ---")

# --- Call functions from the module ---
investment = 150000
profit = 25000
roi = ft.calculate_roi(investment, profit)
print(
    f"ROI for a ${investment:,.2f} investment with ${profit:,.2f} profit is: {roi:.2f}%"
)

principal = 10000
rate = 0.05
years = 10
future_value = ft.calculate_future_value(principal, rate, years)
print(
    f"Future value of ${principal:,.2f} after {years} years at a {rate * 100}% rate is: ${future_value:,.2f}"
)
print("-" * 20)


# --- Exercise 2: Use the `datetime` Module ---
print("--- Solution to Exercise 2 ---")
# import the module

# Get the current date and time
now = datetime.datetime.now()

print(f"Current full date and time: {now}")
print(f"Current date only: {now.date()}")
print(f"Current year: {now.year}")
print(f"Current month: {now.month}")
print(f"Current day: {now.day}")
print("-" * 20)


# --- Exercise 3: Use the `math` Module ---
print("--- Solution to Exercise 3 ---")
# import the module

marketing_budget = 100000
# Use the sqrt function from the math module
growth_factor = math.sqrt(marketing_budget)

print(
    f"The growth factor for a marketing budget of ${marketing_budget:,.2f} is {growth_factor:.2f}."
)
print("-" * 20)