#!/usr/bin/env python

#

# check-py3-compat - check Python 3 compatibility of Mercurial files

#

# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import, print_function

import ast

import importlib

import os

import sys

import traceback

# Modules that have both Python and C implementations.

_dualmodules = (

    'bdiff.py',

    'diffhelpers.py',

    'mpatch.py',

    'parsers.py',

)

def check_compat_py2(f):

    """Check Python 3 compatibility for a file with Python 2"""

    with open(f, 'rb') as fh:

        content = fh.read()

    root = ast.parse(content)

    # Ignore empty files.

    if not root.body:

        return

    futures = set()

    haveprint = False

    for node in ast.walk(root):

        if isinstance(node, ast.ImportFrom):

            if node.module == '__future__':

                futures |= set(n.name for n in node.names)

        elif isinstance(node, ast.Print):

            haveprint = True

    if 'absolute_import' not in futures:

        print('%s not using absolute_import' % f)

    if haveprint and 'print_function' not in futures:

        print('%s requires print_function' % f)

def check_compat_py3(f):

    """Check Python 3 compatibility of a file with Python 3."""

    with open(f, 'rb') as fh:

        content = fh.read()

    try:

        ast.parse(content)

    except SyntaxError as e:

        print('%s: invalid syntax: %s' % (f, e))

        return

    # Try to import the module.

    # For now we only support mercurial.* and hgext.* modules because figuring

    # out module paths for things not in a package can be confusing.

    if f.startswith(('hgext/', 'mercurial/')) and not f.endswith('__init__.py'):

        assert f.endswith('.py')

        name = f.replace('/', '.')[:-3]

        if f.endswith(_dualmodules):

            name = name.replace('.pure.', '.')

        try:

            importlib.import_module(name)

        except Exception as e:

            exc_type, exc_value, tb = sys.exc_info()

            # We walk the stack and ignore frames from our custom importer,

            # import mechanisms, and stdlib modules. This kinda/sorta

            # emulates CPython behavior in import.c while also attempting

            # to pin blame on a Mercurial file.

            for frame in reversed(traceback.extract_tb(tb)):

                if frame.name == '_call_with_frames_removed':

                    continue

                if 'importlib' in frame.filename:

                    continue

                if 'mercurial/__init__.py' in frame.filename:

                    continue

                if frame.filename.startswith(sys.prefix):

                    continue

                break

            if frame.filename:

                filename = os.path.basename(frame.filename)

                print('%s: error importing: <%s> %s (error at %s:%d)' % (

                      f, type(e).__name__, e, filename, frame.lineno))

            else:

                print('%s: error importing module: <%s> %s (line %d)' % (

                      f, type(e).__name__, e, frame.lineno))

if __name__ == '__main__':

    if sys.version_info[0] == 2:

        fn = check_compat_py2

    else:

        fn = check_compat_py3

    for f in sys.argv[1:]:

        fn(f)

    sys.exit(0)