# coding=utf-8
# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
# Licensed under the Apache License, Version 2.0 (see LICENSE).

from __future__ import absolute_import, division, print_function, unicode_literals

import ast

from pants.contrib.python.checks.checker.common import CheckstylePlugin


class ClassFactoring(CheckstylePlugin):
    """Enforces recommendations for accessing class attributes.

    Within classes, if you see:
      class Distiller(object):
        CONSTANT = "Foo"
        def foo(self, value):
           return os.path.join(Distiller.CONSTANT, value)

    recommend using self.CONSTANT instead of Distiller.CONSTANT as otherwise
    it makes subclassing impossible.
    """

    @classmethod
    def name(cls):
        return "class-factoring"

    def iter_class_accessors(self, class_node):
        for node in ast.walk(class_node):
            if (
                isinstance(node, ast.Attribute)
                and isinstance(node.value, ast.Name)
                and (node.value.id == class_node.name)
            ):
                yield node

    def nits(self):
        for class_def in self.iter_ast_types(ast.ClassDef):
            for node in self.iter_class_accessors(class_def):
                yield self.warning(
                    "T800",
                    "Instead of {name}.{attr} use self.{attr} or cls.{attr} with instancemethods and "
                    "classmethods respectively.".format(name=class_def.name, attr=node.attr),
                )