#!/usr/bin/env python3

#

# 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

import warnings

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 |= {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, filename=f)

    except SyntaxError as e:

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

        return

    # Try to import the module.

    # For now we only support modules in packages because figuring out module

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

    if f.startswith(

        ('hgdemandimport/', 'hgext/', 'mercurial/')

    ) and not f.endswith('__init__.py'):

        assert f.endswith('.py')

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

        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:

        # check_compat_py3 will import every filename we specify as long as it

        # starts with one of a few prefixes. It does this by converting

        # specified filenames like 'mercurial/foo.py' to 'mercurial.foo' and

        # importing that. When running standalone (not as part of a test), this

        # means we actually import the installed versions, not the files we just

        # specified. When running as test-check-py3-compat.t, we technically

        # would import the correct paths, but it's cleaner to have both cases

        # use the same import logic.

        sys.path.insert(0, '.')

        fn = check_compat_py3

    for f in sys.argv[1:]:

        with warnings.catch_warnings(record=True) as warns:

            fn(f)

        for w in warns:

            print(

                warnings.formatwarning(

                    w.message, w.category, w.filename, w.lineno

                ).rstrip()

            )

    sys.exit(0)