#!/usr/bin/env python3
"""Merge KEY=value lines from stdin into an env file. Prints key names only."""
import pathlib
import re
import sys

path = pathlib.Path(sys.argv[1])
text = path.read_text() if path.exists() else ""

def upsert(text, key, value):
    line = f"{key}={value}"
    pattern = re.compile("^" + re.escape(key) + "=.*$", re.M)
    if pattern.search(text):
        return pattern.sub(line, text, count=1)
    return text.rstrip() + "\n" + line + "\n"

keys = []
for raw in sys.stdin:
    raw = raw.rstrip("\n")
    if not raw or raw.startswith("#") or "=" not in raw:
        continue
    key, value = raw.split("=", 1)
    text = upsert(text, key, value)
    keys.append(key)

if text and not text.endswith("\n"):
    text += "\n"
path.parent.mkdir(parents=True, exist_ok=True)
path.write_text(text)
print("engine config keys:", ",".join(keys))