#!/usr/bin/env python3
"""Regex rules that repair systematic decompiler output.

These are the fixes that recur across many files, where a patch entry per
occurrence would be hundreds of lines of noise. Each rule is a named regex
with a stated reason, applied to the whole tree.

Rules run after the patch file, because they can rewrite lines a patch already
touched and it is easier to reason about "patches first, then shape rules".

    python fix_decompiler_rules.py <tree>
"""

import os
import re
import sys

RULES = [
    (
        'super-cast-generic-render',
        # RenderLiving<T>.doRender takes T. The decompiler inserted a cast to the
        # supertype, which turns the argument into something that is no longer a T.
        # Passing the variable as declared is always valid here: the parameter is
        # the subclass type this renderer was parameterised with.
        re.compile(r'(super\.\w+\()\((?:Entity|EntityLiving|EntityLivingBase|EntityMob)\)(\s+\w+,)'),
        r'\1\2',
    ),
]


def main():
    if len(sys.argv) != 2:
        print('usage: fix_decompiler_rules.py <tree>')
        return 2
    tree = sys.argv[1]
    touched = {}
    files = set()

    for root, _dirs, names in os.walk(tree):
        for name in names:
            if not name.endswith('.java'):
                continue
            path = os.path.join(root, name)
            with open(path, encoding='utf-8', errors='replace') as handle:
                text = handle.read()
            original = text
            for label, pattern, replacement in RULES:
                new_text = pattern.sub(replacement, text)
                if new_text != text:
                    touched[label] = touched.get(label, 0) + \
                        len(pattern.findall(text))
                    text = new_text
            if text != original:
                files.add(path)
                with open(path, 'w', encoding='utf-8', newline='\n') as handle:
                    handle.write(text)

    if not touched:
        print('decompiler rules: nothing to change')
        return 0
    for label, count in sorted(touched.items()):
        print('  %s: %d' % (label, count))
    print('files rewritten: %d' % len(files))
    return 0


if __name__ == '__main__':
    raise SystemExit(main())