"""Session language helpers for bilingual EN/ES experiments."""


def ensure_language(player):
    """Ensure participant.vars['language'] is set from session.config."""
    if player.participant.vars.get('language') is None:
        player.participant.vars['language'] = player.session.config.get('language', 'en')


def get_language(player):
    ensure_language(player)
    return player.participant.vars['language']


def room_composition_image_basename(majority_n, cost_suffix, lang):
    """PNG filename for room diagram; Spanish sessions use -SP assets."""
    stem = f"{majority_n}A-{cost_suffix}"
    if lang == 'es':
        return f"{stem}-SP.png"
    return f"{stem}.png"


def texts_for(player):
    from experiment_text import TEXT

    ensure_language(player)
    lang = get_language(player)
    return TEXT.get(lang, TEXT['en'])


def merge_t(player, extra=None):
    """Build template context with `t` = all UI strings for this participant."""
    ctx = {'t': texts_for(player)}
    if extra:
        ctx.update(extra)
    return ctx