Source code for cloup.constraints.exceptions

from typing import Iterable, Optional, TYPE_CHECKING

import click
from click import Context, Parameter

from .common import join_param_labels

if TYPE_CHECKING:
    from ._core import Constraint    # pragma: no cover


def default_constraint_error(params: Iterable[Parameter], desc: str) -> str:
    return (
        'the following constraint on parameters [%s] was not satisfied: %s'
        % (join_param_labels(params), desc)
    )


class ConstraintViolated(click.UsageError):
    def __init__(
        self, message: str, ctx: Optional[Context] = None
    ):
        super().__init__(message, ctx=ctx)

    @classmethod
    def default(
        cls, params: Iterable[Parameter], desc: str, ctx: Optional[Context] = None
    ) -> 'ConstraintViolated':
        return ConstraintViolated(
            default_constraint_error(params, desc), ctx=ctx)


class UnsatisfiableConstraint(Exception):
    """ Raised if a constraint cannot be satisfied by a group of parameters
    independently from their values at runtime; e.g. mutually_exclusive cannot
    be satisfied if multiple of the parameters are required. """

    def __init__(
        self, constraint: 'Constraint', params: Iterable[Parameter], reason: str
    ):
        self.constraint = constraint
        self.params = params
        self.reason = reason
        param_names = join_param_labels(params)
        message = (f"\nthe constraint {constraint}\n"
                   f"defined on parameters [{param_names}]\n"
                   f"cannot be satisfied because {reason}")
        super().__init__(message)