import datetime
import logging
import os

import boto3
from boto3.dynamodb.types import TypeSerializer

from tadas.platform import config

STATUS_INGESTED = 'INGESTED'
STATUS_NOT_INGESTED = 'NOT_INGESTED'
STATUS_NOT_AVAILABLE = 'NOT_AVAILABLE'
STATUS_DOWNLOADED = 'DOWNLOADED'

ALL_STATUSES = {
    STATUS_INGESTED,
    STATUS_NOT_INGESTED,
    STATUS_NOT_AVAILABLE,
    STATUS_DOWNLOADED,
}

logger = logging.getLogger(__name__)
serializer = TypeSerializer()


def set_overall_status(feed_name, date, overall_status, details=None):
    """Set overall ingestion status for a (feed_name, date) row in DynamoDB."""

    if overall_status not in ALL_STATUSES:
        raise ValueError(
            f'Unsupported overall status: {overall_status}. '
            f'Available statuses: {ALL_STATUSES}'
        )

    TADAS_UPDATE_DYNAMODB_STATUS = config.get('TADAS_UPDATE_DYNAMODB_STATUS')
    if not TADAS_UPDATE_DYNAMODB_STATUS:
        logger.info(f'Skipping DynamoDB status update {TADAS_UPDATE_DYNAMODB_STATUS=}')
        return

    logger.info(f'Setting overall status for {feed_name=} {date=} {overall_status=} {details=}')
    attributes = {}
    now = datetime.datetime.now(datetime.UTC).replace(microsecond=0)
    attributes['updated_at'] = now.isoformat()
    if details:
        attributes['details'] = details

    update_dynamodb_status(
        feed_name=feed_name,
        date=date,
        status=overall_status,
        attributes=attributes,
        dynamodb_table=os.environ['FEED_INGESTION_TABLE'],
        aws_region=os.environ.get('AWS_REGION', 'us-east-1'),
    )


def update_dynamodb_status(
        feed_name, date, status,
        dynamodb_table, aws_region,
        attributes=None):

    if not date:
        raise ValueError('no date')
    # validating date format. Will raise ValueError if invalid.
    datetime.datetime.strptime(date, '%Y-%m-%d')

    dynamodb = boto3.client('dynamodb', region_name=aws_region)

    key = {
        'feed_name': {'S': feed_name},
        'date': {'S': date},
    }

    attributes = attributes or {}
    attributes['status'] = status

    expression_attribute_names = {f'#{k}': k for k in attributes.keys()}
    expression_attribute_values = {
        f':{k}': serializer.serialize(v)
        for k, v in attributes.items()
    }
    update_expression = ', '.join(f'#{k} = :{k}' for k in attributes.keys())
    update_expression = f'SET {update_expression}'

    dynamodb.update_item(
        TableName=dynamodb_table,
        Key=key,
        UpdateExpression=update_expression,
        ExpressionAttributeNames=expression_attribute_names,
        ExpressionAttributeValues=expression_attribute_values,
    )