# Let us print a welcome message to start.
print('Welcome to the Python Temperature Converter!')

# Here we create a variable called celsius and assign it a value.
celsius = 20

# Let us print the value of celsius.
print('Celsius temperature:', celsius)

# Let us convert Celsius to Fahrenheit using a formula.
fahrenheit = celsius * 9 / 5 + 32
print('Fahrenheit temperature:', fahrenheit)

# Ask the user to type a Celsius value.
celsius = input('Enter a temperature in Celsius: ')
# Convert the input from a string to a number.
celsius = float(celsius)
fahrenheit = celsius * 9 / 5 + 32
print('That is', fahrenheit, 'degrees Fahrenheit.')

# What if the user enters something that is not a number?
# Let us handle it with a try-except block.
try:
    celsius = float(input('Type a temperature in Celsius: '))
    fahrenheit = celsius * 9 / 5 + 32
    print('That is', fahrenheit, 'degrees Fahrenheit.')
except ValueError:
    print('That was not a number. Please try again.')
    

# Define a temperature conversion function.
def celsius_to_fahrenheit(c):
    return c * 9 / 5 + 32

# Try it out:
temp = 100
print(temp, 'Celsius is', celsius_to_fahrenheit(temp), 'Fahrenheit.')

# Can we also convert Fahrenheit to Celsius? Let us make a new function.
def fahrenheit_to_celsius(f):
    return (f - 32) * 5 / 9

# Let us try converting ninety-eight point six Fahrenheit to Celsius.
print('98.6 Fahrenheit is', fahrenheit_to_celsius(98.6), 'Celsius.')

# Ask the user what type of conversion they want.
choice = input('Type C to convert Celsius to Fahrenheit, or F for Fahrenheit to Celsius: ')
if choice == 'C':
    c = float(input('Enter Celsius: '))
    print(c, 'Celsius is', celsius_to_fahrenheit(c), 'Fahrenheit.')
elif choice == 'F':
    f = float(input('Enter Fahrenheit: '))
    print(f, 'Fahrenheit is', fahrenheit_to_celsius(f), 'Celsius.')
else:
    print('Sorry, that is not a valid choice!')
    

# What if we want to convert a lot of temperatures?
# Lists help us store many values.
temps_c = [0, 10, 20, 30, 40]
for t in temps_c:
    print(t, 'C =', celsius_to_fahrenheit(t), 'F')
    

# We can also store each result in a new list using a loop.
converted = []
for c in temps_c:
    converted.append(celsius_to_fahrenheit(c))
print('All Fahrenheit values:', converted)

# Let us use a list comprehension for a shorter way.
temps_f = [celsius_to_fahrenheit(c) for c in temps_c]
print('With list comprehension:', temps_f)

# What if we want only temperatures above freezing?
above_freezing = [c for c in temps_c if c > 0]
print('Celsius values above zero:', above_freezing)

# Welcome the user and ask their name.
print('Welcome to the Full Temperature Converter!')
name = input('What is your name? ')
print('Hi,', name + '!')

# Ask which conversion and handle case differences.
convert_choice = input('Type C to convert Celsius to Fahrenheit, or F for Fahrenheit to Celsius: ').upper()
try:
    if convert_choice == 'C':
        c = float(input('Enter Celsius value: '))
        f = celsius_to_fahrenheit(c)
        print(c, 'Celsius is', f, 'Fahrenheit.')
    elif convert_choice == 'F':
        f = float(input('Enter Fahrenheit value: '))
        c = fahrenheit_to_celsius(f)
        print(f, 'Fahrenheit is', c, 'Celsius.')
    else:
        print('Not a valid choice! Please pick C or F.')
except ValueError:
    print('That was not a number. Please try again.')
    

# Say goodbye at the end.
print('Thank you for using the converter! Have a great day!')

# Common mistake: forgetting to convert input() to float.
temp = input('Enter a Celsius temperature: ')
# print(celsius_to_fahrenheit(temp))  # This would cause an error.
print('Be sure to turn input into a number before converting!')

# Bonus: Convert a whole list typed by the user.
numbers = input('Enter Celsius values separated by commas: ')
c_list = [float(n) for n in numbers.split(',')]
f_list = [celsius_to_fahrenheit(c) for c in c_list]
print('Converted:', f_list)