"""S3 common functions."""

import boto3
import botocore

from src import config

client = boto3.client('s3')
resource = boto3.resource('s3')


def head_object(bucket, key):
    """Retrieve object metadata without object downloading.

    Args:
        bucket (str): target S3 bucket.
        key (str): target object key.

    Returns:
        dict: object metadata.
    """
    try:
        return client.head_object(
            Bucket=bucket,
            Key=key,
            ExpectedBucketOwner=config.EXPECTED_BUCKET_OWNER
        )
    except botocore.exceptions.ClientError as e:
        if e.response['Error']['Code'] == '404':
            return None

        raise


def download_file_object(bucket, key, file_object, **kwargs):
    """Download s3 object to file-like buffer.

    Args:
        bucket (str): target S3 bucket.
        key (str): target S3 key.
        file_object (io.BytesIO): file data.
        kwargs (dict): extra arguments.
    """
    return client.download_fileobj(
        Bucket=bucket,
        Key=key,
        Fileobj=file_object,
        ExtraArgs={'ExpectedBucketOwner': config.EXPECTED_BUCKET_OWNER},
        **kwargs
    )