import random
import json
from datetime import datetime, timezone
from otree.api import *

doc = """
Instructions and language choice.
"""
def get_language_and_lexicon(player, strict=True):
    from .lexicon_fr import Lexicon as LexiconFR
    from .lexicon_en import Lexicon as LexiconEN

    lang = ( 
        player.participant.vars['language']
        if strict
        else player.participant.vars.get('language') or player.field_maybe_none('language')
    )

    if lang not in ['fr', 'en']:
        raise ValueError(f"Unsupported or missing language: {lang}")

    if lang == 'fr':
        return LexiconFR, 'fr'
    else:
        return LexiconEN, 'en'


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

class Subsession(BaseSubsession):
    pass

def creating_session(subsession):
    for player in subsession.get_players():
        player.participant.vars['language'] = 'en'

class Group(BaseGroup):
    pass


def utc_now_iso():
    return datetime.now(timezone.utc).isoformat()


def append_page_timestamp(player, field_name, page_name):
    raw = player.field_maybe_none(field_name) or '{}'
    try:
        payload = json.loads(raw)
    except json.JSONDecodeError:
        payload = {}
    if field_name == 'page_shown_at_utc' and page_name in payload:
        return
    payload[page_name] = utc_now_iso()
    setattr(player, field_name, json.dumps(payload, ensure_ascii=True))


class Player(BasePlayer):
    language = models.StringField()
    page_shown_at_utc = models.LongStringField(blank=True)
    page_submitted_at_utc = models.LongStringField(blank=True)


# FUNCTIONS
# No creating_session function needed - treatment assignment removed

# PAGES
class LanguageSelection(Page):
    form_model = 'player'
    form_fields = ['language']

    @staticmethod
    def is_displayed(player):
        return player.round_number == 1

    @staticmethod
    def before_next_page(player, timeout_happened):
        append_page_timestamp(player, 'page_submitted_at_utc', LanguageSelection.__name__)
        if player.language:
            player.participant.vars['language'] = player.language

    @staticmethod
    def vars_for_template(player):
        append_page_timestamp(player, 'page_shown_at_utc', LanguageSelection.__name__)
        return {}


class Instructions(Page):
    @staticmethod
    def is_displayed(player):
        return 'language' in player.participant.vars

    @staticmethod
    def vars_for_template(player):
        append_page_timestamp(player, 'page_shown_at_utc', Instructions.__name__)
        from . import get_language_and_lexicon
        Lexicon, lang = get_language_and_lexicon(player)
        return dict(
            Lexicon=Lexicon,
            lang=lang,
        )

    @staticmethod
    def before_next_page(player, timeout_happened):
        append_page_timestamp(player, 'page_submitted_at_utc', Instructions.__name__)

page_sequence = [Instructions]