"""
S3 Utils
========

Utils for any S3 operations for ows-accounting.
"""

import boto3
from botocore.exceptions import ClientError


def extract_bucket_path(url):
    """Extract bucket name and object key from url.

    Args:
        url (str): S3 URL like 's3://bucket_name/folder1/folder2/'.

    Return:
        tuple: bucket name and bucket path.
    """

    if url.startswith('s3://'):
        url_parts = url.split('/', 3)
        return url_parts[2], url_parts[3]

    raise Exception("The S3 url '{url}' is not valid.".format(url=url))


def get_presigned_url(bucket, key, expiration_time=3600):
    """Get presigned url.

    Args:
       bucket (str): s3 bucket name.
       key (str): s3 key.
       expiration_time (int): seconds after which link will be expired.

    Returns:
       str: presigned url.
    """

    s3 = boto3.client('s3')
    return s3.generate_presigned_url(
        ClientMethod='get_object',
        Params={
            'Bucket': bucket,
            'Key': key
        },
        ExpiresIn=expiration_time)


def object_exists(bucket, key):
    """Check if s3 object exists.

    Args:
        bucket (str): Bucket name. For example, myBucket
        key (str): full path to s3 object. For example,
            archives/file_part1.gz

    Returns:
        bool: True if exists, False otherwise.
    """

    try:
        client = boto3.client('s3')
        client.head_object(Bucket=bucket, Key=key)
        return True
    except ClientError:
        return False