from ._compat import PY2, filename_to_ui, get_text_stderr
from .utils import echo


class ClickException(Exception):
    """An exception that Click can handle and show to the user."""

    #: The exit code for this exception
    exit_code = 1

    def __init__(self, message):
        if PY2:
            Exception.__init__(self, message.encode('utf-8'))
        else:
            Exception.__init__(self, message)
        self.message = message

    def format_message(self):
        return self.message

    def show(self, file=None):
        if file is None:
            file = get_text_stderr()
        echo('Error: %s' % self.format_message(), file=file)


class UsageError(ClickException):
    """An internal exception that signals a usage error.  This typically
    aborts any further handling.

    :param message: the error message to display.
    :param ctx: optionally the context that caused this error.  Click will
                fill in the context automatically in some situations.
    """
    exit_code = 2

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

    def show(self, file=None):
        if file is None:
            file = get_text_stderr()
        if self.ctx is not None:
            echo(self.ctx.get_usage() + '\n', file=file)
        echo('Error: %s' % self.format_message(), file=file)


class BadParameter(UsageError):
    """An exception that formats out a standardized error message for a
    bad parameter.  This is useful when thrown from a callback or type as
    Click will attach contextual information to it (for instance, which
    parameter it is).

    .. versionadded:: 2.0

    :param param: the parameter object that caused this error.  This can
                  be left out, and Click will attach this info itself
                  if possible.
    :param param_hint: a string that shows up as parameter name.  This
                       can be used as alternative to `param` in cases
                       where custom validation should happen.  If it is
                       a string it's used as such, if it's a list then
                       each item is quoted and separated.
    """

    def __init__(self, message, ctx=None, param=None,
                 param_hint=None):
        UsageError.__init__(self, message, ctx)
        self.param = param
        self.param_hint = param_hint

    def format_message(self):
        if self.param_hint is not None:
            param_hint = self.param_hint
        elif self.param is not None:
            param_hint = self.param.opts or [self.param.name]
        else:
            return 'Invalid value: %s' % self.message
        if isinstance(param_hint, (tuple, list)):
            param_hint = ' / '.join('"%s"' % x for x in param_hint)
        return 'Invalid value for %s: %s' % (param_hint, self.message)


class FileError(ClickException):
    """Raised if a file cannot be opened."""

    def __init__(self, filename, hint=None):
        ui_filename = filename_to_ui(filename)
        if hint is None:
            hint = 'unknown error'
        ClickException.__init__(self, hint)
        self.ui_filename = ui_filename
        self.filename = filename

    def format_message(self):
        return 'Could not open file %s: %s' % (self.ui_filename, self.message)


class Abort(RuntimeError):
    """An internal signalling exception that signals Click to abort."""