#!/usr/bin/env python3
"""Add a DllOverrides entry to a Wine prefix's user.reg.

Usage: add-dll-override.py USER_REG DLL VALUE
e.g.   add-dll-override.py ~/.../Blizzard/user.reg ddraw native,builtin

Only safe while no wineserver is live for that prefix - Wine rewrites user.reg
from memory when the last process exits, which would drop the edit.
"""
import sys

SECTION = r'[Software\\Wine\\DllOverrides]'


def main(path, dll, value):
    with open(path, encoding='utf-8', errors='surrogateescape') as fh:
        text = fh.read()

    entry = '"%s"="%s"\n' % (dll, value)
    if entry in text:
        print('already set: %s = %s' % (dll, value))
        return 0

    i = text.find(SECTION)
    if i == -1:
        text = text.rstrip('\n') + '\n\n' + SECTION + ' 0\n' + entry
    else:
        j = text.index('\n', i) + 1          # past the section header
        while j < len(text) and text[j] == '#':   # past #time= and friends
            j = text.index('\n', j) + 1
        text = text[:j] + entry + text[j:]

    with open(path, 'w', encoding='utf-8', errors='surrogateescape') as fh:
        fh.write(text)
    print('set: %s = %s' % (dll, value))
    return 0


if __name__ == '__main__':
    if len(sys.argv) != 4:
        sys.exit(__doc__)
    sys.exit(main(*sys.argv[1:]))