#!/usr/bin/env python2.7

from __future__ import print_function

import marshal
import struct
import sys
import time
import uncompyle6
from pathlib2 import Path

def _pack_uint32(val):
    """ Convert integer to 32-bit little-endian bytes """
    return struct.pack("<I", val)

def code_to_bytecode(code, mtime=0, source_size=0):
    """
    Serialise the passed code object (PyCodeObject*) to bytecode as a .pyc file
    The args mtime and source_size are inconsequential metadata in the .pyc file.
    """

    # Get the magic number for the running Python version
    if sys.version_info >= (3,4):
        from importlib.util import MAGIC_NUMBER
    else:
        import imp
        MAGIC_NUMBER = imp.get_magic()

    # Add the magic number that indicates the version of Python the bytecode is for
    #
    # The .pyc may not decompile if this four-byte value is wrong. Either hardcode the
    # value for the target version (eg. b'\x33\x0D\x0D\x0A' instead of MAGIC_NUMBER)
    # or see trymagicnum.py to step through different values to find a valid one.
    data = bytearray(MAGIC_NUMBER)

    # Handle extra 32-bit field in header from Python 3.7 onwards
    # See: https://www.python.org/dev/peps/pep-0552
    if sys.version_info >= (3,7):
        # Blank bit field value to indicate traditional pyc header
        data.extend(_pack_uint32(0))

    data.extend(_pack_uint32(int(mtime)))

    # Handle extra 32-bit field for source size from Python 3.2 onwards
    # See: https://www.python.org/dev/peps/pep-3147/
    if sys.version_info >= (3,2):
        data.extend(_pack_uint32(source_size))

    data.extend(marshal.dumps(code))

    return data


if len(sys.argv) < 3:
    print("Usage %s <in_path> <pyc_path> <py_path>" % sys.argv[0])
    sys.exit(1)

in_path = Path(sys.argv[1])
pyc_path = Path(sys.argv[2])
py_path = Path(sys.argv[3])

for path in in_path.rglob("*.co"):
    try:
        co = marshal.loads(path.read_bytes())
        pyc = code_to_bytecode(co, time.time())

        pyc_file = pyc_path / path.relative_to(in_path).with_suffix(".pyc")
        pyc_file.parent.mkdir(parents=True, exist_ok=True)

        with open(str(pyc_file), "wb") as file:
            file.write(pyc)

        py_file = py_path / path.relative_to(in_path).with_suffix(".py")
        py_file.parent.mkdir(parents=True, exist_ok=True)

        with open(str(py_file), 'w') as decompiled:
            uncompyle6.main.decompile_file(str(pyc_file), decompiled)
    except:
        print("Failed to decompile %s" % path)