from otree.api import *
import random


doc = """
Payment app: selects one random paying round (common to all participants)
based on per-round payoffs stored in participant.vars['payoffs'].
"""


class C(BaseConstants):
    NAME_IN_URL = 'payment_info'
    PLAYERS_PER_GROUP = None
    NUM_ROUNDS = 1


class Subsession(BaseSubsession):
    def creating_session(self):
        # Only choose once per session
        if 'paying_round' not in self.session.vars:

            num_rounds = None

            # Find any participant who has stored per-round payoffs
            for participant in self.session.get_participants():
                payoffs = participant.vars.get('payoffs')
                if isinstance(payoffs, (list, tuple)) and len(payoffs) > 0:
                    num_rounds = len(payoffs)
                    break

            if num_rounds is None:
                # Fallback if nothing found: default to round 1
                num_rounds = 1

            # Choose one common paying round for ALL participants
            self.session.vars['paying_round'] = random.randint(1, num_rounds)


class Group(BaseGroup):
    pass


class Player(BasePlayer):
    # payoff from the randomly selected paying round
    bonus = models.CurrencyField(default=0)


class Payment(Page):
    @staticmethod
    def vars_for_template(player: Player):
        participant = player.participant
        session = player.session

        # The paying round was set in creating_session
        paying_round = session.vars.get('paying_round', 1)

        # Retrieve per-round payoffs
        payoffs = participant.vars.get('payoffs', [])

        if isinstance(payoffs, (list, tuple)) and len(payoffs) >= paying_round:
            selected_payoff = payoffs[paying_round - 1]
        else:
            selected_payoff = cu(0)

        # Store for record (optional)
        player.bonus = selected_payoff

        # Make sure your SESSION_CONFIG has 'participation_fee'
        participation_fee = session.config.get('participation_fee', cu(0))

        # Final payment = payoff from random round + participation fee
        total_payment = selected_payoff + participation_fee

        return {
            "final_payoff": selected_payoff,
            "bonus": selected_payoff,
            "participation_fee": participation_fee,
            "total_payment": total_payment,
            "paying_round": paying_round,
        }


page_sequence = [Payment]