"""S3 common functions."""

import boto3
from botocore import exceptions
from oto import response

from constants import errors

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


def get_object(bucket, key):
    """Get S3 object.

    Args:
        bucket (str): target S3 bucket.
        key (str): target S3 key.
    """
    return client.get_object(Bucket=bucket, Key=key)


def object_exists(bucket, key):
    """Check if S3 object exists.

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

    Return:
         response.Response: Response object with success or error details.
    """
    try:
        client.head_object(Bucket=bucket, Key=key)
        return response.Response({'status': errors.SUCCESS_CODE})
    except exceptions.ClientError as e:
        error_code = e.response['Error']['Code']
        if error_code == '404':
            error_message = errors.ERROR_MESSAGE_S3_FILE_NOT_FOUND.format(
                key=key, bucket=bucket)
            return response.create_not_found_response(error_message)
        elif error_code == '403':
            error_message = errors.ERROR_MESSAGE_S3_FILE_ACCESS_DENIED.format(
                key=key, bucket=bucket)
            return response.create_error_response(
                errors.ERROR_CODE_S3_FILE_ACCESS_DENIED, error_message,
                status=403)
        else:
            error_message = errors.ERROR_MESSAGE_S3_FILE_FAILED_TO_HEAD.format(
                key=key, bucket=bucket, error=str(e))
            return response.create_fatal_response(error_message)


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

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

    Returns:
        dict: Response from S3.
    """
    return client.head_object(Bucket=bucket, Key=key)


def download_object(bucket, key, local_filename):
    """Download S3 object from a bucket.

    Args:
        bucket (str): target S3 bucket.
        key (str): target object key.
        local_filename (str): path where file should be saved.

    Returns:
        str: path to downloaded file.
    """
    my_bucket = resource.Bucket(bucket)
    my_bucket.download_file(key, local_filename)
    return local_filename