#  Licensed under the Apache License, Version 2.0 (the "License"); you may
#  not use this file except in compliance with the License. You may obtain
#  a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#  License for the specific language governing permissions and limitations
#  under the License.

import abc
import inspect

import six

from cliff import argparse


@six.add_metaclass(abc.ABCMeta)
class Command(object):
    """Base class for command plugins.

    :param app: Application instance invoking the command.
    :paramtype app: cliff.app.App

    """

    deprecated = False

    _description = ''
    _epilog = None

    def __init__(self, app, app_args, cmd_name=None):
        self.app = app
        self.app_args = app_args
        self.cmd_name = cmd_name
        return

    def get_description(self):
        """Return the command description.

        The default is to use the first line of the class' docstring
        as the description. Set the ``_description`` class attribute
        to a one-line description of a command to use a different
        value. This is useful for enabling translations, for example,
        with ``_description`` set to a string wrapped with a gettext
        translation marker.

        """
        # NOTE(dhellmann): We need the trailing "or ''" because under
        # Python 2.7 the default for the docstring is None instead of
        # an empty string, and we always want this method to return a
        # string.
        desc = self._description or inspect.getdoc(self.__class__) or ''
        # The base class command description isn't useful for any
        # real commands, so ignore that value.
        if desc == inspect.getdoc(Command):
            desc = ''
        return desc

    def get_epilog(self):
        """Return the command epilog."""
        return self._epilog

    def get_parser(self, prog_name):
        """Return an :class:`argparse.ArgumentParser`.
        """
        parser = argparse.ArgumentParser(
            description=self.get_description(),
            epilog=self.get_epilog(),
            prog=prog_name,
            formatter_class=_SmartHelpFormatter,
        )
        return parser

    @abc.abstractmethod
    def take_action(self, parsed_args):
        """Override to do something useful.

        The returned value will be returned by the program.
        """

    def run(self, parsed_args):
        """Invoked by the application when the command is run.

        Developers implementing commands should override
        :meth:`take_action`.

        Developers creating new command base classes (such as
        :class:`Lister` and :class:`ShowOne`) should override this
        method to wrap :meth:`take_action`.

        Return the value returned by :meth:`take_action` or 0.
        """
        return self.take_action(parsed_args) or 0


class _SmartHelpFormatter(argparse.HelpFormatter):
    """Smart help formatter to output raw help message if help contain \n.

    Some command help messages maybe have multiple line content, the built-in
    argparse.HelpFormatter wrap and split the content according to width, and
    ignore \n in the raw help message, it merge multiple line content in one
    line to output, that looks messy. SmartHelpFormatter keep the raw help
    message format if it contain \n, and wrap long line like HelpFormatter
    behavior.
    """

    def _split_lines(self, text, width):
        lines = text.splitlines() if '\n' in text else [text]
        wrap_lines = []
        for each_line in lines:
            wrap_lines.extend(
                super(_SmartHelpFormatter, self)._split_lines(each_line, width)
            )
        return wrap_lines