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# to you under the Apache License, Version 2.0 (the
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import json
from json import JSONDecodeError

from wtforms.validators import EqualTo, ValidationError


class GreaterEqualThan(EqualTo):
    """Compares the values of two fields.

    :param fieldname:
        The name of the other field to compare to.
    :param message:
        Error message to raise in case of a validation error. Can be
        interpolated with `%(other_label)s` and `%(other_name)s` to provide a
        more helpful error.
    """

    def __call__(self, form, field):
        try:
            other = form[self.fieldname]
        except KeyError:
            raise ValidationError(field.gettext(f"Invalid field name '{self.fieldname}'."))

        if field.data is None or other.data is None:
            return

        if field.data < other.data:
            message_args = {
                'other_label': hasattr(other, 'label') and other.label.text or self.fieldname,
                'other_name': self.fieldname,
            }
            message = self.message
            if message is None:
                message = field.gettext(
                    f"Field must be greater than or equal to {message_args['other_label']}."
                )
            else:
                message = message % message_args

            raise ValidationError(message)


class ValidJson:
    """Validates data is valid JSON.

    :param message:
        Error message to raise in case of a validation error.
    """

    def __init__(self, message=None):
        self.message = message

    def __call__(self, form, field):
        if field.data:
            try:
                json.loads(field.data)
            except JSONDecodeError as ex:
                message = self.message or f'JSON Validation Error: {ex}'
                raise ValidationError(message=field.gettext(message.format(field.data)))
