contracts.py

"""
    contracts.py

    Copyright (c) 2013-2021 Snowplow Analytics Ltd. All rights reserved.

    This program is licensed to you under the Apache License Version 2.0,
    and you may not use this file except in compliance with the Apache License
    Version 2.0. You may obtain a copy of the Apache License Version 2.0 at
    http://www.apache.org/licenses/LICENSE-2.0.

    Unless required by applicable law or agreed to in writing,
    software distributed under the Apache License Version 2.0 is distributed on
    an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
    express or implied. See the Apache License Version 2.0 for the specific
    language governing permissions and limitations there under.

    Authors: Anuj More, Alex Dean, Fred Blundun, Paul Boocock, Matus Tomlein
    Copyright: Copyright (c) 2013-2021 Snowplow Analytics Ltd
    License: Apache License Version 2.0
"""

import traceback
import re
from typing import Any, Dict, Iterable, Callable, Sized
from snowplow_tracker.typing import FORM_TYPES, FORM_NODE_NAMES

_CONTRACTS_ENABLED = True
_MATCH_FIRST_PARAMETER_REGEX = re.compile(r"\(([\w.]+)[,)]")


def disable_contracts() -> None:
    global _CONTRACTS_ENABLED
    _CONTRACTS_ENABLED = False


def enable_contracts() -> None:
    global _CONTRACTS_ENABLED
    _CONTRACTS_ENABLED = True


def contracts_enabled() -> bool:
    global _CONTRACTS_ENABLED
    return _CONTRACTS_ENABLED


def greater_than(value: float, compared_to: float) -> None:
    if contracts_enabled() and value <= compared_to:
        raise ValueError("{0} must be greater than {1}.".format(_get_parameter_name(), compared_to))


def non_empty(seq: Sized) -> None:
    if contracts_enabled() and len(seq) == 0:
        raise ValueError("{0} is empty.".format(_get_parameter_name()))


def non_empty_string(s: str) -> None:
    if contracts_enabled() and type(s) is not str or not s:
        raise ValueError("{0} is empty.".format(_get_parameter_name()))


def one_of(value: Any, supported: Iterable) -> None:
    if contracts_enabled() and value not in supported:
        raise ValueError("{0} is not supported.".format(_get_parameter_name()))


def satisfies(value: Any, check: Callable[[Any], bool]) -> None:
    if contracts_enabled() and not check(value):
        raise ValueError("{0} is not allowed.".format(_get_parameter_name()))


def form_element(element: Dict[str, Any]) -> None:
    satisfies(element, lambda x: _check_form_element(x))


def _get_parameter_name() -> str:
    stack = traceback.extract_stack()
    _, _, _, code = stack[-3]

    match = _MATCH_FIRST_PARAMETER_REGEX.search(code)
    if not match:
        return 'Unnamed parameter'
    return match.groups(0)[0]


def _check_form_element(element: Dict[str, Any]) -> bool:
    """
        Helper method to check that dictionary conforms element
        in sumbit_form and change_form schemas
    """
    all_present = isinstance(element, dict) and 'name' in element and 'value' in element and 'nodeName' in element
    try:
        if element['type'] in FORM_TYPES:
            type_valid = True
        else:
            type_valid = False
    except KeyError:
        type_valid = True
    return all_present and element['nodeName'] in FORM_NODE_NAMES and type_valid