"""Exclusive cohorts; convert legacy DB-local registration timestamps to Europe/Berlin."""
from datetime import date, datetime, time, timedelta
import os
from zoneinfo import ZoneInfo

COHORTS = ('alpha_tester', 'beta_tester', 'early_bird')


def boundaries():
    alpha = date.fromisoformat(os.environ.get('ALPHA_TESTER_UNTIL', '2026-10-31'))
    beta = date.fromisoformat(os.environ.get('BETA_TESTER_UNTIL', '2026-12-31'))
    if beta <= alpha:
        raise ValueError('BETA_TESTER_UNTIL must be after ALPHA_TESTER_UNTIL')
    return (datetime.combine(alpha + timedelta(days=1), time()),
            datetime.combine(beta + timedelta(days=1), time()))


def cohort(registered_at):
    if registered_at.tzinfo:
        registered_at = registered_at.astimezone(ZoneInfo('Europe/Berlin')).replace(tzinfo=None)
    alpha_end, beta_end = boundaries()
    return 'alpha_tester' if registered_at < alpha_end else 'beta_tester' if registered_at < beta_end else 'early_bird'


def reconcile(cursor, user_id=None):
    """Also upgrades existing beta members and reclassifies when configured dates change."""
    alpha_end, beta_end = boundaries()
    cursor.execute('''
        DELETE FROM user_badges b USING users u WHERE b.user_id=u.id
        AND (%s::integer IS NULL OR u.id=%s)
        AND b.badge_code=ANY(%s) AND b.badge_code <> CASE
            WHEN u.created_at AT TIME ZONE current_setting('TimeZone') AT TIME ZONE 'Europe/Berlin' < %s THEN 'alpha_tester'
            WHEN u.created_at AT TIME ZONE current_setting('TimeZone') AT TIME ZONE 'Europe/Berlin' < %s THEN 'beta_tester' ELSE 'early_bird' END
    ''', (user_id, user_id, list(COHORTS), alpha_end, beta_end))
    cursor.execute('''
        INSERT INTO user_badges(user_id,badge_code,awarded_at)
        SELECT id, CASE
            WHEN created_at AT TIME ZONE current_setting('TimeZone') AT TIME ZONE 'Europe/Berlin' < %s THEN 'alpha_tester'
            WHEN created_at AT TIME ZONE current_setting('TimeZone') AT TIME ZONE 'Europe/Berlin' < %s THEN 'beta_tester'
            ELSE 'early_bird' END, created_at
        FROM users WHERE (%s::integer IS NULL OR id=%s)
        ON CONFLICT(user_id,badge_code) DO NOTHING
    ''', (alpha_end, beta_end, user_id, user_id))