unit_converter.py

#!/usr/bin/env python3
"""
Unit Converter CLI Tool
Supports: Length, Weight, and Temperature conversions
"""

def convert_length(value, from_unit, to_unit):
    """Convert between length units"""
    # Convert to meters first
    to_meters = {
        'mm': 0.001,
        'cm': 0.01,
        'm': 1,
        'km': 1000,
        'inch': 0.0254,
        'ft': 0.3048,
        'yard': 0.9144,
        'mile': 1609.34
    }
    
    meters = value * to_meters[from_unit]
    return meters / to_meters[to_unit]


def convert_weight(value, from_unit, to_unit):
    """Convert between weight units"""
    # Convert to kilograms first
    to_kg = {
        'mg': 0.000001,
        'g': 0.001,
        'kg': 1,
        'ton': 1000,
        'oz': 0.0283495,
        'lb': 0.453592
    }
    
    kg = value * to_kg[from_unit]
    return kg / to_kg[to_unit]


def convert_temperature(value, from_unit, to_unit):
    """Convert between temperature units"""
    # Convert to Celsius first
    if from_unit == 'c':
        celsius = value
    elif from_unit == 'f':
        celsius = (value - 32) * 5/9
    elif from_unit == 'k':
        celsius = value - 273.15
    
    # Convert from Celsius to target
    if to_unit == 'c':
        return celsius
    elif to_unit == 'f':
        return celsius * 9/5 + 32
    elif to_unit == 'k':
        return celsius + 273.15


def display_menu():
    """Display main menu"""
    print("\n" + "="*50)
    print("       UNIT CONVERTER CLI TOOL")
    print("="*50)
    print("\n1. Length Conversion")
    print("2. Weight Conversion")
    print("3. Temperature Conversion")
    print("4. Exit")
    print("-"*50)


def length_menu():
    """Handle length conversion"""
    print("\nLength Units: mm, cm, m, km, inch, ft, yard, mile")
    try:
        value = float(input("Enter value: "))
        from_unit = input("From unit: ").lower()
        to_unit = input("To unit: ").lower()
        
        result = convert_length(value, from_unit, to_unit)
        print(f"\n✓ {value} {from_unit} = {result:.4f} {to_unit}")
    except (KeyError, ValueError) as e:
        print(f"\n✗ Error: Invalid input. Please check units and value.")


def weight_menu():
    """Handle weight conversion"""
    print("\nWeight Units: mg, g, kg, ton, oz, lb")
    try:
        value = float(input("Enter value: "))
        from_unit = input("From unit: ").lower()
        to_unit = input("To unit: ").lower()
        
        result = convert_weight(value, from_unit, to_unit)
        print(f"\n✓ {value} {from_unit} = {result:.4f} {to_unit}")
    except (KeyError, ValueError) as e:
        print(f"\n✗ Error: Invalid input. Please check units and value.")


def temperature_menu():
    """Handle temperature conversion"""
    print("\nTemperature Units: c (Celsius), f (Fahrenheit), k (Kelvin)")
    try:
        value = float(input("Enter value: "))
        from_unit = input("From unit: ").lower()
        to_unit = input("To unit: ").lower()
        
        result = convert_temperature(value, from_unit, to_unit)
        print(f"\n✓ {value}°{from_unit.upper()} = {result:.2f}°{to_unit.upper()}")
    except (KeyError, ValueError) as e:
        print(f"\n✗ Error: Invalid input. Please check units and value.")


def main():
    """Main program loop"""
    while True:
        display_menu()
        choice = input("Select option (1-4): ")
        
        if choice == '1':
            length_menu()
        elif choice == '2':
            weight_menu()
        elif choice == '3':
            temperature_menu()
        elif choice == '4':
            print("\nThank you for using Unit Converter!")
            break
        else:
            print("\n✗ Invalid choice. Please select 1-4.")


if __name__ == "__main__":
    main()