# 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
import re

from six import PY3

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


class PrintStatements(CheckstylePlugin):
    """Enforce the use of print as a function and not a statement."""

    @classmethod
    def name(cls):
        return "print-statements"

    FUNCTIONY_EXPRESSION = re.compile(r"^\s*\(.*\)\s*$")

    def nits(self):
        if PY3:
            # Python 3 interpreter will raise SyntaxError upon reading a print statement.
            # So, this module cannot be meaningfully used when ran with a Python 3 interpreter.
            return
        # MyPy says this is unreachable when run with Python 3
        for print_stmt in self.iter_ast_types(ast.Print):  # type: ignore[misc]
            # In Python 3.x and in 2.x with __future__ print_function, prints show up as plain old
            # function expressions.  ast.Print does not exist in Python 3.x.  However, allow use
            # syntactically as a function, i.e. ast.Print but with ws "(" .* ")" ws
            logical_line = "".join(self.python_file[print_stmt.lineno])
            print_offset = logical_line.index("print")
            stripped_line = logical_line[print_offset + len("print") :]
            if not self.FUNCTIONY_EXPRESSION.match(stripped_line):
                yield self.error("T607", "Print used as a statement.", print_stmt)