Who's Yo Daddy?

# who_is_your_daddy.py
# Who's Yo Daddy?
#
# User can enter name of a male and produce the name of his father.
# User is able to add, replace, and delete son-father pairs.
#
# Heidi Heffelfinger
# November 12, 2012
# Programming Python for the Absolute Beginner 3rd Ed. Chapter 5
# Challenge 3

# welcome user and explain game
print(
"""
    Welcome to Who's Yo Daddy!

    This program allows you to find fathers of particular sons.
    You can also add, replace, or delete father-son pairs.

    Have fun!
"""
)

# create dictionary
paternal_pairs ={"Hans Johnson": "Zacharias Johnson",
                 "Alexander Melville Bell": "Alexander Graham Bell",
                 "Sakichi Toyoda": "Kiichiro Toyoda",
                 "Wilbert Gore": "Robert Gore",
                 "Mark Chamberlain": "Alex Oxlade-Chamberlain",
                 "Johan Cruyff": "Jordi Cruyff",
                 "Paul Ince": "Thomas Ince",
                 "Zinedine Zidane": "Enzo Zidane",
                 "Kirk Douglas": "Michael Douglas",
                 "Donald Sutherland": "Kiefer Sutherland"}

# initialize variables
choice = None

# program
while choice != 0:
    print(
    """
    Who's Yo Daddy:

    0 - Exit
    1 - Look Up a Son of a Father
    2 - Add Father-Son Pair
    3 - Remove Father-Son Pair
    4 - Replace Son in Father-Son Pair
    5 - Replace Father in Father-Son Pair
    6 - Replace Father and Son in Father-Son Pair
    7 - List All Father-Son Pairs
    """
    )

    choice = input("What would you like to do?: ")
    print()

    # exit
    if choice == "0":
        print("Goodbye")
        break

    # look up father-son pair
    elif choice == "1":
        father = input("What is the father's name?: ")
        if father in paternal_pairs:
            son = paternal_pairs[father]
            print("\nThe son of", father, "is", son)
        else:
            print("Sorry, that father is not listed. Try adding "\
                  "a father-son pair.")

    # add a father-son pair
    elif choice == "2":
        father = input("What is the full name of the father you wish to add? ")
        if father not in paternal_pairs:
            son = input("\nWhat is the full name of the son?: ")
            paternal_pairs[father] = son
            print("\n", father, "with son,", son, "has been added.")
        else:
            print("\nThat father is already in the list. Try replacing.")

    # remove father-son pair
    elif choice == "3":
        father = input("What is the full name of the father for the pair "\
                       "you wish to delete?: ")
        if father in paternal_pairs:
            del paternal_pairs[father]
            print("\nOK, the pair has been deleted.")
        else:
            print("\nI cannot do that!", father, "doesn't exist in list.")

    # replace son in father-son pair
    elif choice == "4":
        father = input("What is the full name of the father for the pair "\
                       "you wish to replace the son of?: ")
        if father in paternal_pairs:
            son = input("\nWhat is the full name of the son?: ")
            paternal_pairs[father] = son
            print("\nOK,", son, "has been added to", father)
        else:
            print("\nThat father doesn't exist in list! Try adding him.")

    # replace father in father-son pair
    elif choice == "5":
        father = input("What is the full name of the father for the pair "\
                       "you wish to replace the father in?: ")
        if father in paternal_pairs:
            new_father = input("\nWhat is the full name of the new father?: ")
            paternal_pairs[new_father] = paternal_pairs[father]
            print("\nOK,", father, "has been replaced with", new_father)
            del paternal_pairs[father]
        else:
            print("\nThat father doesn't exist in list! Try adding him.")

    # replace entire father-son pair
    elif choice == "6":
        father = input("What is the full name of the father for the pair "\
                       "you wish to replace?: ")
        if father in paternal_pairs:
            new_father = input("\nWhat is the full name of the new father?: ")
            son = input("What is the full name of the new son?: ")
            paternal_pairs[new_father] = son
            print("\nOK,", father, "and his son,", paternal_pairs[father],\
                  "have been replaced with", new_father, "and his son,",\
                  paternal_pairs[new_father])
            del paternal_pairs[father]
        else:
            print("\nThat father doesn't exist in list! Try adding him.")

    # list all father-son pairs
    elif choice == "7":
        for father, son in paternal_pairs.items():
            print(father, "and his son,", son)

    # some unknown choice
    else:
        print("\nSorry, but", choice, "isn't a valid choice.")

# wait for user
input("\n\nPress the enter key to exit.")