"""Module for asset status logic tier."""

from datetime import datetime
import os

from asset_transcoder.constants import asset_status as asset_status_const
from asset_transcoder.models import asset_status as asset_status_model
from asset_transcoder.models import asset_upload as asset_upload_model
from asset_transcoder.utils import signed_urls
from asset_transcoder.utils.exceptions import OwsError


def _convert_timestamp_to_datetime(timestamp):
    """Convert str timestamp to datetime object.

    Args:
        timestamp (str): String timestamp representation
    Returns:
        datetime.datetime: converted object
    """
    return datetime.strptime(timestamp, '%Y-%m-%dT%H:%M:%S.%fZ')


def create_status(filename, status, errors, timestamp, session=None):
    """Save information about asset status. Called by the handler.

    Args:
        filename (object): the unique filename of the asset.
        status (str): Asset processing status.
        errors (dict): Errors if present.
        timestamp (str): Asset status event timestamp.
        session (sqlalchemy.Session): db connection

    Returns:
        dict: Saved status info or error.
    """
    clean_filename, ext = os.path.splitext(filename)
    asset_upload = asset_upload_model.get_asset_upload(clean_filename)
    return create_status_with_upload(asset_upload, status, errors, timestamp, session)


def create_status_with_upload(asset_upload, status, errors, timestamp, session=None):
    """Save information about asset status.

    Args:
        asset_upload (object): Asset Upload record.
        status (str): Asset processing status.
        errors (dict): Errors if present.
        timestamp (str): Asset status event timestamp.
        session (sqlalchemy.Session): db connection

    Returns:
        dict: Saved status info or error.
    """
    if status not in asset_status_const.PROCESSING_VALID_STATUSES:
        raise OwsError.bad_request('Status {0} is not valid for processing'.format(status))
    created_date = _convert_timestamp_to_datetime(timestamp)
    return asset_status_model.create_asset_status(
        asset_upload_id=asset_upload.asset_upload_id,
        status=status,
        created_date=created_date,
        errors=errors,
        session=session
    )


def get_status(filename, signed_url_policy, signed_url_duration):
    """Get status for filename.

    Args:
        filename (str): Unique source asset filename.
        signed_url_policy (str): Constant instructing how to sign urls.
        signed_url_duration (int): Number of minutes that signed urls are valid for.
    Returns:
        dict: Saved status info.
    """
    clean_filename, ext = os.path.splitext(filename)
    asset_upload = asset_upload_model.get_asset_upload(clean_filename)

    try:
        last_status = asset_status_model.get_last_asset_status(asset_upload.asset_upload_id)
    except OwsError as err:
        if err.status == 404:
            return {
                'status': asset_status_const.STATUS_NOT_STARTED,
                'description': '',
                'assets': []
            }
        else:
            raise
    if last_status['status'] == 'encoding_completed':
        assets = [asset_upload.to_dict_with_finals()]
        assets = signed_urls.sign_urls(assets, signed_url_policy, signed_url_duration)
        last_status['assets'] = assets[0]['asset_finals']

    return last_status