"""JSON Draft3 Schema Validator Wrapper.

A Wrapper for a JSON Draft3 schema validation library which allows us to
transform the results into an internal Response() format.
"""

from images import response
from images.constants import errors as error_constants


def _filter(data):
    """Sanitize a dictionary of request input data.

    Sanitize a dictionary of request input data. (e.g. headers or body)
    before applying JSON schema validations to it. This includes:
    1.) Stripping leading or trailing space from strings.
    2.) Replacing empty strings with None.

    Args:
        data (dict): the data to be sanitized.

    Returns:
        dict: a sanitized version of the given data
    """
    for key, value in data.items():
        if isinstance(value, str):
            data[key] = value.strip()
        if data[key] == '':
            data[key] = None
    return data


def validate(data, validator, failure_status=400):
    """Generic JSON Draft3 Schema Vaidation.

    Args:
        data (dict): the JSON to be validated.
        schema (Draft3Validator): the JSON Draft3 Schema to validate against.

    Returns:
        Response: the response of the create operation.
    """
    errors = {}
    data = _filter(data)
    for error in sorted(validator.iter_errors(data), key=str):
        if error.relative_path:
            errors[error.relative_path.pop()] = error.message
        elif error.absolute_schema_path:
            errors[error.absolute_schema_path.pop()] = error.message

    if errors:
        return response.create_error_response(
            code=error_constants.VALIDATION_ERROR,
            message=errors,
            status=failure_status)

    return response.Response(message={'status': 'ok'}, status=200)