"""Run Typst watchers with readable, document-specific output."""

from pathlib import Path
from queue import Empty, Queue
import signal
import subprocess
import sys
from threading import Thread


def relay(process, label, messages):
    with process.stdout:
        for line in process.stdout:
            messages.put((label, line.rstrip()))
    messages.put((label, None))


def interrupted(signum, frame):
    raise KeyboardInterrupt


def main():
    separator = sys.argv.index("--")
    executable, *flags = sys.argv[1:separator]
    sources = sys.argv[separator + 1:]
    messages = Queue()
    processes = []
    signal.signal(signal.SIGTERM, interrupted)
    try:
        for source in sources:
            process = subprocess.Popen(
                [executable, "watch", *flags, source, str(Path(source).with_suffix(".pdf"))],
                stdout=subprocess.PIPE,
                stderr=subprocess.STDOUT,
                text=True,
                encoding="utf-8",
                errors="replace",
                start_new_session=True,
            )
            processes.append(process)
            Thread(target=relay, args=(process, source, messages), daemon=True).start()
        while True:
            try:
                label, line = messages.get(timeout=0.2)
            except Empty:
                continue
            if line is None:
                print(f"[{label}] Watch-Prozess unerwartet beendet.", file=sys.stderr)
                return 1
            if line:
                print(f"[{label}] {line}", flush=True)
    except KeyboardInterrupt:
        print("\nÜberwachung beendet.", flush=True)
        return 0
    except OSError as error:
        print(f"Watch konnte nicht gestartet werden: {error}", file=sys.stderr)
        return 1
    finally:
        # Stop all watchers, including when startup fails partway through.
        for process in processes:
            if process.poll() is None:
                process.terminate()
        for process in processes:
            try:
                process.wait(timeout=3)
            except subprocess.TimeoutExpired:
                process.kill()
                process.wait()


if __name__ == "__main__":
    sys.exit(main())