# 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 six import PY3

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


class ExceptStatements(CheckstylePlugin):
    """Do not allow non-3.x-compatible and/or dangerous except statements."""

    @classmethod
    def name(cls):
        return "except-statement"

    @classmethod
    def blanket_excepts(cls, node):
        for handler in node.handlers:
            if handler.type is None and handler.name is None:
                return handler

    @classmethod
    def iter_excepts(cls, tree):
        for ast_node in ast.walk(tree):
            if isinstance(ast_node, ast.Try if PY3 else ast.TryExcept):
                yield ast_node

    def nits(self):
        for try_except in self.iter_excepts(self.python_file.tree):
            # Check case 1, blanket except
            handler = self.blanket_excepts(try_except)
            if handler:
                yield self.error("T803", "Blanket except: not allowed.", handler)

            # Check case 2, except Foo, bar:
            for handler in try_except.handlers:
                statement = "".join(self.python_file[handler.lineno])
                except_index = statement.index("except")
                except_suffix = statement[except_index + len("except") :]

                if handler.name and " as " not in except_suffix:
                    yield self.error("T601", "Old-style except statements forbidden.", handler)