from datetime import datetime

from aws_lambda_powertools import Logger
from aws_lambda_powertools.utilities.data_classes import (
    EventBridgeEvent,
    event_source,
)
from aws_lambda_powertools.utilities.typing import LambdaContext
from layercake.dateutils import fromisoformat, now
from layercake.dynamodb import DynamoDBPersistenceLayer, KeyPair, SortKey, TransactKey
from layercake.funcs import pick

from boto3clients import dynamodb_client
from config import ENROLLMENT_TABLE, ORDER_TABLE
from utils import get_billing_period

logger = Logger(__name__)
enrollment_layer = DynamoDBPersistenceLayer(ENROLLMENT_TABLE, dynamodb_client)
order_layer = DynamoDBPersistenceLayer(ORDER_TABLE, dynamodb_client)


@event_source(data_class=EventBridgeEvent)
@logger.inject_lambda_context
def lambda_handler(event: EventBridgeEvent, context: LambdaContext) -> bool:
    now_ = now()
    new_image = event.detail['new_image']
    enrollment_id = new_image['id']
    subscription = enrollment_layer.collection.get_items(
        TransactKey(enrollment_id)
        + SortKey('METADATA#SUBSCRIPTION_COVERED')
        + SortKey('CANCELED', path_spec='canceled_by', rename_key='canceled_by')
    )

    created_at: datetime = fromisoformat(new_image['created_at'])  # type: ignore
    start_period, end_period = get_billing_period(
        billing_day=int(subscription['billing_day']),
        date_=created_at,
    )
    pk = 'BILLING#ORG#{org_id}'.format(org_id=subscription['org_id'])
    sk = 'START#{start}#END#{end}'.format(
        start=start_period.isoformat(),
        end=end_period.isoformat(),
    )

    if now_.date() > end_period:
        logger.debug('Enrollment outside the billing period')
        return False

    try:
        canceled_by = subscription.get('canceled_by')
        # Retrieve canceled enrollment data
        old_enrollment = order_layer.collection.get_item(
            KeyPair(
                pk=pk,
                sk=f'{sk}#ENROLLMENT#{enrollment_id}',
            ),
            exc_cls=EnrollmentNotFoundError,
        )

        order_layer.put_item(
            item={
                'id': pk,
                'sk': f'{sk}#ENROLLMENT#{enrollment_id}#CANCELED',
                'unit_price': old_enrollment['unit_price'] * -1,
                'created_at': now_,
            }
            | pick(('user', 'course', 'enrolled_at'), old_enrollment)
            # Add `created_by` if present
            | ({'author': canceled_by} if canceled_by else {}),
            # Post-migration: uncomment the following line
            # | ({'created_by': canceled_by} if canceled_by else {}),
            cond_expr='attribute_not_exists(sk)',
        )
    except Exception as exc:
        logger.exception(
            exc,
            keypair={'pk': pk, 'sk': sk},
        )
        return False
    else:
        return True


class EnrollmentNotFoundError(Exception): ...