#!/usr/bin/env python3
"""Build the configured operator frontend from its fixed working directory.

No npm lifecycle hooks, standalone typechecks, tests or native builds. The
caller groups related frontend edits before invoking this delivery command.
"""
import os
import fcntl
from pathlib import Path
import shutil
import subprocess
import sys
import time


def main():
    web = Path(__file__).resolve().parents[1] / "web"
    vite = web / "node_modules/vite/bin/vite.js"
    node = shutil.which("node")
    if not node or not vite.is_file():
        print(f"Frontend dependency unavailable: node={node}, Vite={vite}", file=sys.stderr)
        return 2
    env = {**os.environ, "FREECAD_WEB_FAST_LINK": "ON"}
    # The foreground session and the sole scheduler share web/dist. Keep the
    # lock outside dist: Vite clears that directory before writing a bundle.
    with (web / ".freecad-web-frontend-build.lock").open("a") as lock:
        started = time.monotonic()
        waiting = False
        while True:
            try:
                fcntl.flock(lock.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
                break
            except BlockingIOError:
                if not waiting:
                    print("Waiting for the existing frontend delivery to release web/dist", flush=True)
                    waiting = True
                if time.monotonic() - started >= 1800:
                    print("Frontend delivery lock timed out; retain edits and resume after the active build", file=sys.stderr)
                    return 124
                time.sleep(0.25)
        # Vite retains the descriptor if the outer runner exits mid-delivery.
        return subprocess.run([node, str(vite), "build"], cwd=web, env=env,
                              pass_fds=(lock.fileno(),), check=False).returncode


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