"""Function Logic."""
from datetime import datetime
import json

from content_utils.exceptions import IneligibleEventError

from src import config
from src.constants import ADD_INDEX_OP
from src.exceptions import ReviewQueueItemExplicitSkip


def _extract_update_data(db_msg, payload):
    """Extract update data from db message and update payload."""
    locked_by_user_id = db_msg.get_field_values('locked_by_user_id')
    locked_until_datetime = db_msg.get_field_values('locked_until_datetime')

    is_changed_locked_by_user_id = locked_by_user_id.get('before') != locked_by_user_id.get('after')
    is_changed_locked_until_datetime = (
        locked_until_datetime.get('before') != locked_until_datetime.get('after'))

    if not (is_changed_locked_by_user_id or is_changed_locked_until_datetime):
        raise IneligibleEventError(
            f'skip operation: {db_msg.operation}, before: {json.dumps(db_msg.before)}, after: {json.dumps(db_msg.after)}')  # noqa

    if is_changed_locked_by_user_id:
        payload['locked_by_user_id'] = locked_by_user_id.get('after')
    if is_changed_locked_until_datetime:
        payload['locked_until_datetime'] = (
            locked_until_datetime.get('after') and (
                f"{datetime.utcfromtimestamp(locked_until_datetime.get('after') / 1e6).isoformat()}Z") # noqa
        )


def parse_message_payload(db_msg):
    """Process a single CDC event from review queue."""
    payload = _get_payload(db_msg)
    product_id = payload.get('product_id')
    review_queue_id = payload.get('id')

    if review_queue_id in config.SKIP_REVIEW_QUEUE_ITEMS:
        raise ReviewQueueItemExplicitSkip('Explicit Skip')

    operation_type, payload = _determine_operation_type(db_msg, payload, product_id)

    return {
        'product_id': product_id,
        'review_queue_id': review_queue_id,
        'payload': payload,
        'operation_type': operation_type
    }


def _get_payload(db_msg):
    """Extract payload from db message."""
    return db_msg.after if db_msg.after is not None else db_msg.before


def _determine_operation_type(db_msg, payload, product_id):
    """Determine the operation type and modify payload if necessary."""
    status = db_msg.get_field_values('status')
    is_update = db_msg.operation == 'u' and not (
        status.get('before') == 'applying' and status.get('after') == 'new')
    is_deindex = db_msg.operation == 'd' or (
        is_update and status.get('before') == 'new' and status.get('after') == 'complete')
    is_no_op = db_msg.operation == 'c' and status.get('after') == 'complete'

    if is_no_op:
        raise IneligibleEventError(
            f'skip operation: {db_msg.operation}, before: {json.dumps(db_msg.before)}, after: {json.dumps(db_msg.after)}')  # noqa
    elif is_deindex:
        return 'deindex', None
    elif is_update:
        payload = {'product_id': product_id}
        _extract_update_data(db_msg, payload)
        return 'update_index', payload
    else:
        return ADD_INDEX_OP, payload