# 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


# Warn on non 2.x/3.x compatible symbols:
#   - basestring
#   - xrange
#
# Methods:
#   - .iteritems
#   - .iterkeys
#   - .itervalues
#
# Comprehension builtins
#   - filter
#   - map
#   - range
#
#   => Make sure that these are not assigned.
#   Warn if they are assigned or returned directly from functions
#
# Class internals:
#   __metaclass__
class FutureCompatibility(CheckstylePlugin):
    """Warns about behavior that will likely break when moving to Python 3.x."""

    @classmethod
    def name(cls):
        return "future-compat"

    BAD_ITERS = frozenset({"iteritems", "iterkeys", "itervalues"})
    BAD_FUNCTIONS = frozenset({"xrange"})
    BAD_NAMES = frozenset({"basestring", "unicode"})

    def nits(self):
        for call in self.iter_ast_types(ast.Call):
            if isinstance(call.func, ast.Attribute):
                # Not a perfect solution since a user could have a dictionary named six or something similar
                #   However, this should catch most cases where people are using iter* without six.
                if call.func.attr in self.BAD_ITERS and getattr(call.func.value, "id", "") != "six":
                    yield self.error(
                        "T602",
                        "{attr} disappears in Python 3.x.  Use non-iter instead.".format(
                            attr=call.func.attr
                        ),
                        call,
                    )
            elif isinstance(call.func, ast.Name):
                if call.func.id in self.BAD_FUNCTIONS:
                    yield self.error(
                        "T603",
                        "Please avoid {func_id} as it disappears in Python 3.x.".format(
                            func_id=call.func.id
                        ),
                        call,
                    )
        for name in self.iter_ast_types(ast.Name):
            if name.id in self.BAD_NAMES:
                yield self.error(
                    "T604",
                    "Please avoid {id} as it disappears in Python 3.x.".format(id=name.id),
                    name,
                )
        for class_def in self.iter_ast_types(ast.ClassDef):
            for node in class_def.body:
                if not isinstance(node, ast.Assign):
                    continue
                for name in node.targets:
                    if not isinstance(name, ast.Name):
                        continue
                    if name.id == "__metaclass__":
                        yield self.warning(
                            "T605",
                            "This metaclass style is deprecated and gone entirely in Python 3.x.",
                            name,
                        )