"""Loopback shim server for the desktop update hand-off.

Two GET routes: / serves ui.html, /progress serves the status file the
orchestrator script writes ({"status": "running"|"done"|"error", ...}).
Exists because a file:// page cannot receive events from a detached
process. Prints the chosen ephemeral port on stdout, serves until killed.

`elapsed_seconds` is stamped per request, not read from the status file:
stages are minutes apart, so a value frozen at the last publish would sit
still through the longest waits -- exactly the stall the page exists to
disprove. Windows' in-process listener computes it the same way.
"""

import http.server
import json
import os
import socketserver
import sys
import threading
import time

html_path, status_path = sys.argv[1], sys.argv[2]
started_at = float(sys.argv[3]) if len(sys.argv) > 3 else time.time()
owner_pid = int(sys.argv[4]) if len(sys.argv) > 4 else 0
with open(html_path, "rb") as f:
    HTML = f.read()


def exit_with_owner():
    """Never outlive the hand-off: it ignores TERM/HUP, so a killed orchestrator
    used to leave this server running on the old venv's python forever."""
    while True:
        time.sleep(2)
        try:
            os.kill(owner_pid, 0)  # windows-footgun: ok — posix.sh-only helper (Windows has its own listener)
        except ProcessLookupError:
            os._exit(0)
        except OSError:
            pass


def progress_body():
    try:
        with open(status_path, "rb") as f:
            state = json.loads(f.read())
        if not isinstance(state, dict):
            raise ValueError(state)
    except Exception:
        state = {"status": "running", "message": ""}
    state["elapsed_seconds"] = max(0, int(time.time() - started_at))

    return json.dumps(state).encode("utf-8")


class Handler(http.server.BaseHTTPRequestHandler):
    def log_message(self, format, *args):
        pass

    def do_GET(self):
        if self.path.startswith("/progress"):
            body = progress_body()
            ctype = "application/json; charset=utf-8"
        elif self.path == "/":
            body, ctype = HTML, "text/html; charset=utf-8"
        else:
            self.send_response(404)
            self.end_headers()
            return
        self.send_response(200)
        self.send_header("Content-Type", ctype)
        self.send_header("Content-Length", str(len(body)))
        self.send_header("Cache-Control", "no-store")
        self.end_headers()
        self.wfile.write(body)


with socketserver.TCPServer(("127.0.0.1", 0), Handler) as srv:
    if owner_pid > 0:
        threading.Thread(target=exit_with_owner, daemon=True).start()
    print(srv.server_address[1], flush=True)
    srv.serve_forever()