import random

def rock_paper_scissors():
    choices = ['rock', 'paper', 'scissors']
    
    computer_choice = random.choice(choices)
    player_choice = ''
    
    while player_choice not in choices:
        player_choice = input("Choose rock, paper, or scissors: ").lower()
    
    print(f"You chose {player_choice}.")
    print(f"Computer chose {computer_choice}.")

    if player_choice == computer_choice:
        print("It's a tie!")
    elif player_choice == "rock":
        if computer_choice == "scissors":
            print("You win!")
        else:
            print("You lose!")
    elif player_choice == "paper":
        if computer_choice == "rock":
            print("You win!")
        else:
            print("You lose!")
    else:  # player chose scissors
        if computer_choice == "paper":
            print("You win!")
        else:
            print("You lose!")

# To play the game
# rock_paper_scissors()