import random

# Check that users have entered a valid option based on a list
def string_checker(question, valid_ans=("yes", "no")):

    error = f"Please enter a valid option from the following list: {valid_ans}"

    while True:

          # Get user response and make sure it's lowercase
          user_response = input(question).lower()

          for item in valid_ans:
               # check if the user response is a word in the list
               if item == user_response:
                   return item

               # check if the user response is the same as the first letter of an item in the list
               elif user_response == item[0]:
                return item

          # print error if user does not enter something valid
          print(error)
          print()

# Displays instructions
def instructions():
    # Prints instructions

    print(""" 
*** Instructions ***

To begin, choose the number of rounds (or press <enter> for infinite mode).

Then play against the computer. You need to choose R (rock), P (paper) or S (scissors).

The rules are as follows:
* Paper covers rock
* Rock crushes scissors
* Scissors cuts paper

Press <xxx> to end the game at any time.

Good Luck! """)

# Checks for an integer more than 0 (allows <enter>)
def int_check(question):

    while True:
        error = "Please enter an integer that is 1 or more."

        to_check = input(question)

        # check for infinite mode
        if to_check == "":
             return "infinite"

        try:
            response = int(to_check)

            # check that the number is more than / equal to 1
            if response < 1:
                print(error)

            else:
               return response

        except ValueError:
            print(error)

# Compares user / computer choice and returns
# result (win / lose / tie)
def rps_compare(user, comp):

    # If the user and the computer choice is the same, it's a tie
    if user == comp:
        result = "tie"

    # There are 3 ways to win
    elif user == "paper" and comp == "rock":
        result = "win"
    elif user == "rock" and comp == "scissors":
        result = "win"
    elif user == "scissors" and comp == "paper":
        result = "win"

    # If it's not a win / tie, then it's a loss
    else:
        result = "lose"

    return result


# Main Routine starts here

# Initialise game variables
mode = "regular"
rounds_played = 0

rps_list = ["rock", "paper", "scissors", "xxx"]

print(" o[]= Rock / Paper / Scissors Game =[]o ")
print()

# Ask user if they want to see instructions, and display if requested

want_instructions = string_checker("Do you want to read the instructions? ")

# Checks user enters yes (y) or no (n)
if want_instructions == "yes":
    instructions()

# Ask user for number of rounds / infinite mode
num_rounds = int_check("How many rounds would you like? Push 'enter' for infinite mode ")

if num_rounds == 'infinite':
    mode = "infinite"
    print("you chose infinite")
    num_rounds = 5

# Game loop starts here
while rounds_played < num_rounds:

    # Rounds headings
    if mode == "infinite":
        rounds_heading = f"\n.=+ Round {rounds_played + 1} (Infinite Mode) +=."
    else:
        rounds_heading = f"\n .=+ Round {rounds_played + 1} of {num_rounds} +=."

    print(rounds_heading)
    print()

    # Randomly choose from the rps list (excluding the exit code)
    comp_choice = random.choice(rps_list[:-1])
    print("Computer choice: ", comp_choice)

    # Get user choice
    user_choice = string_checker("Choose: ", rps_list)

    # If user choice is the exit code, break the loop
    if user_choice == "xxx":
        break


    result = rps_compare(user_choice, comp_choice)
    print(f"{user_choice} vs {comp_choice}, {result}")


    rounds_played += 1

    # if users are in infinite mode, increase number of rounds!
    if mode == "infinite":
     num_rounds += 1

# Game loop ends here

# Game History / Statistics area