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# to you under the Apache License, Version 2.0 (the
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#   http://www.apache.org/licenses/LICENSE-2.0
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import jinja2.sandbox


class SandboxedEnvironment(jinja2.sandbox.SandboxedEnvironment):
    """SandboxedEnvironment for Airflow task templates."""

    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        self.filters.update(FILTERS)

    def is_safe_attribute(self, obj, attr, value):
        """
        Allow access to ``_`` prefix vars (but not ``__``).

        Unlike the stock SandboxedEnvironment, we allow access to "private" attributes (ones starting with
        ``_``) whilst still blocking internal or truely private attributes (``__`` prefixed ones).
        """
        return not jinja2.sandbox.is_internal_attribute(obj, attr)


def ds_filter(value):
    return value.strftime('%Y-%m-%d')


def ds_nodash_filter(value):
    return value.strftime('%Y%m%d')


def ts_filter(value):
    return value.isoformat()


def ts_nodash_filter(value):
    return value.strftime('%Y%m%dT%H%M%S')


def ts_nodash_with_tz_filter(value):
    return value.isoformat().replace('-', '').replace(':', '')


FILTERS = {
    'ds': ds_filter,
    'ds_nodash': ds_nodash_filter,
    'ts': ts_filter,
    'ts_nodash': ts_nodash_filter,
    'ts_nodash_with_tz': ts_nodash_with_tz_filter,
}