"""Amazon S3 connector."""
import boto3
from botocore.errorfactory import ClientError
from oto import response
from sentry_sdk import capture_exception


class S3FileNotFound(Exception):
    """
    Exceptions that raises if provided key wasn't found in bucket.

    Attributes:
       key (str): Wrong provided key.
       bucket (str): S3 Bucket.
    """

    def __init__(self, key, bucket):
        """Show exception message.

        Args:
            key (str): Key that wasn't found in provided bucket.
            bucket (str): Bucket where key had to exist.
        """
        Exception.__init__(self, '{key} not found in bucket {bucket}!'.format(
            key=key, bucket=bucket))


def connect_to_s3():
    """Connect to S3.

    Connect to S3 via AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY env variables

    Returns:
         S3Connection: S3Connection object provides access to s3.
    """
    conn = boto3.Session()
    s3_connection = conn.client('s3')
    return s3_connection


def get_s3_file_url(s3_connection, bucket_name, file_key, expires_in=86400):
    """Generate download url for provided file in s3 bucket.

    Args:
        s3_connection (S3Connection): S3Connection object authorized in s3.
        bucket_name (str): name of bucket where file is stored.
        file_key (str): path to file for which url should be generated.
        expires_in (int): lifetime of url. Default is 1 day.

    Returns:
        Response: Response with url in message or with errors.
    """
    try:
        s3_connection.head_bucket(Bucket=bucket_name)
        try:
            s3_connection.head_object(Bucket=bucket_name, Key=file_key)
        except ClientError:
            raise S3FileNotFound(key=file_key, bucket=bucket_name)
        url = s3_connection.generate_presigned_url(
            'get_object',
            Params={'Bucket': bucket_name, 'Key': file_key},
            ExpiresIn=expires_in)
        return response.Response(url)
    except ClientError as ex:
        capture_exception(ex)
        return response.create_error_response(
            code=ex.response['Error']['Code'],
            message=ex.response['Error']['Message'],
            status=ex.response['ResponseMetadata']['HTTPStatusCode'])
    except S3FileNotFound as ex:
        capture_exception(ex)
        return response.create_not_found_response(
            message=ex.args[0])