#!/usr/bin/env python
# Portions Copyright (c) Facebook, Inc. and its affiliates.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2.

# 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.

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

from __future__ import absolute_import, print_function

import ast
import importlib
import os
import sys
import traceback


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 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:
        fn = check_compat_py3

    for f in sys.argv[1:]:
        fn(f)

    sys.exit(0)