from die import Die

class Yahtzee:
    """A command-line Yahtzee game.
    This version of Yahtzee is initialized with a list of goals.
    """
    def __init__(self, goals):
        """Initialize a new game of Yahtzee.
        Creates a score of zero, stores the list of goals, and sets up five dice.
        """
        self.score = 0
        self.goals = goals
        self.dice = [Die() for num in range(5)]

    def play(self):
        """Play an entire game.
        Greets the player, resets the score and goals, and continues playing rounds
        until all goals have been used. Prints the final score at the end.
        """
        print("Welcome to Yachtzee!")
        self.score = 0
        for goal in self.goals:
            goal.used = False
        while self.count_unused_goals() > 0:
            self.play_round()
        print(f"Your final score was {self.score}")

    def play_round(self):
        """Play a single round of Yahtzee.
        Rolls all dice, lets the player choose a goal or re-roll, and updates the score.
        """
        print("=" * 80)
        self.rolls_left = 3
        for die in self.dice:
            die.roll()
        self.show_status()
        goal = self.choose_goal()
        goal.used = True
        self.score += goal.score(self.dice)

    def show_status(self):
        """Display the current game status.
        Shows the current score, number of rolls left, and the faces of all dice.
        """
        dice = ', '.join([str(die) for die in self.dice])
        print(f"Score: {self.score}. Rolls left: {self.rolls_left}. Dice: {dice}.")

    def choose_goal(self):
        """Prompt the player to choose a goal or re-roll.
        Builds a list of unused goals, displays them, and processes the player's choice.
        If the player chooses to re-roll, performs a re-roll and re-prompts for a goal.
        """
        options = []
        unused_goals = self.get_unused_goals()
        for goal in unused_goals:
            option = goal.prompt(self.dice)
            options.append(option)
        if self.rolls_left > 0:
            options.append("Re-roll")
        choice = self.get_choice(options)
        if options[choice] == "Re-roll":
            self.reroll()
            self.show_status()
            return self.choose_goal()
        else:
            return unused_goals[choice]

    def get_choice(self, options):
         """Display available options and get the player's choice.
        Validates user input and returns the chosen option as an integer index.
        """
        print("What would you like to do?")
        for i, option in enumerate(options):
            print(f"{i}. {option}")
        choice = input("> ")
        while not self.option_choice_is_valid(choice, options):
            print("Sorry, that's not a valid choice.")
            choice = input("> ")
        return int(choice)

    def option_choice_is_valid(self, choice, options):
        """Check whether the player's input is a valid choice.
        Ensures the input is a number and within the range of available options.
        """
        if not choice.isdigit():
            return False
        if int(choice) < 0:
            return False
        if int(choice) >= len(options):
            return False
        return True

    def count_unused_goals(self):
        """Return the number of unused goals left in the game."""
        return len(self.get_unused_goals())

    def get_unused_goals(self):
         """Return a list of goals that have not yet been used."""
        unused_goals = []
        for goal in self.goals:
            if not goal.used:
                unused_goals.append(goal)
        return unused_goals

    def reroll(self):
         """Re-roll selected dice.
        Decreases the number of rolls left, asks the player which dice to re-roll,
        and rolls the chosen dice again.
        """
        self.rolls_left -= 1
        choices = self.get_reroll_choices()
        dice_to_reroll = self.get_dice_to_reroll(choices)
        for die in dice_to_reroll:
            die.roll()

    def get_dice_to_reroll(self, choice_ints):
         """Identify which dice to re-roll based on the player's choices.
        Matches chosen face values with current dice faces and returns a list of dice to roll again.
        """
        dice_to_reroll = []
        for die in self.dice:
            if die.face in choice_ints:
                choice_ints.remove(die.face)
                dice_to_reroll.append(die)
        return dice_to_reroll

    def get_reroll_choices(self):
         """Ask the player which dice to re-roll.
        Prompts for input, validates the choices, and returns them as a list of integers.
        """
        print("Which dice do you want to re-roll?")
        choices = input("> ")
        while not self.reroll_choices_are_valid(choices):
            print("Please enter the numbers on dice you want to re-roll.")
            choices = input("> ")
        choice_ints = [int(digit) for digit in choices]
        return choice_ints
        
    def reroll_choices_are_valid(self, choices_str):
         """Validate the player's re-roll choices.
        Checks that all characters are digits and correspond to actual dice values.
        """
        if not choices_str.isdigit():
            return False
        choice_ints = [int(digit) for digit in choices_str]
        for die in self.dice:
            if die.face in choice_ints:
                choice_ints.remove(die.face)
        return len(choice_ints) == 0