from six import string_types
from six.moves.urllib.parse import urlparse, parse_qs
from samtranslator.model.exceptions import InvalidResourceException


def parse_s3_uri(uri):
    """Parses a S3 Uri into a dictionary of the Bucket, Key, and VersionId

    :return: a BodyS3Location dict or None if not an S3 Uri
    :rtype: dict
    """
    if not isinstance(uri, string_types):
        return None

    url = urlparse(uri)
    query = parse_qs(url.query)

    if url.scheme == 's3' and url.netloc and url.path:
        s3_pointer = {
            'Bucket': url.netloc,
            'Key': url.path.lstrip('/')
        }
        if 'versionId' in query and len(query['versionId']) == 1:
            s3_pointer['Version'] = query['versionId'][0]
        return s3_pointer
    else:
        return None


def to_s3_uri(code_dict):
    """Constructs a S3 URI string from given code dictionary

    :param dict code_dict: Dictionary containing Lambda function Code S3 location of the form
                          {S3Bucket, S3Key, S3ObjectVersion}
    :return: S3 URI of form s3://bucket/key?versionId=version
    :rtype string
    """

    try:
        uri = "s3://{bucket}/{key}".format(bucket=code_dict["S3Bucket"], key=code_dict["S3Key"])
        version = code_dict.get("S3ObjectVersion", None)
    except (TypeError, AttributeError):
        raise TypeError("Code location should be a dictionary")

    if version:
        uri += "?versionId=" + version

    return uri


def construct_s3_location_object(location_uri, logical_id, property_name):
    """Constructs a Lambda `Code` or `Content` property, from the SAM `CodeUri` or `ContentUri` property.
    This follows the current scheme for Lambda Functions and LayerVersions.

    :param dict or string location_uri: s3 location dict or string
    :param string logical_id: logical_id of the resource calling this function
    :param string property_name: name of the property which is used as an input to this function.
    :returns: a Code dict, containing the S3 Bucket, Key, and Version of the Lambda layer code
    :rtype: dict
    """
    if isinstance(location_uri, dict):
        if not location_uri.get("Bucket") or not location_uri.get("Key"):
            # location_uri is a dictionary but does not contain Bucket or Key property
            raise InvalidResourceException(logical_id,
                                           "'{}' requires Bucket and Key properties to be "
                                           "specified".format(property_name))

        s3_pointer = location_uri

    else:
        # location_uri is NOT a dictionary. Parse it as a string
        s3_pointer = parse_s3_uri(location_uri)

        if s3_pointer is None:
            raise InvalidResourceException(logical_id,
                                           '\'{}\' is not a valid S3 Uri of the form '
                                           '"s3://bucket/key" with optional versionId query '
                                           'parameter.'.format(property_name))

    code = {
        'S3Bucket': s3_pointer['Bucket'],
        'S3Key': s3_pointer['Key']
    }
    if 'Version' in s3_pointer:
        code['S3ObjectVersion'] = s3_pointer['Version']
    return code