#!/usr/bin/env python3
"""dim-probe.py — measure what a headless kiosk actually renders.

A kiosk has no keyboard, no monitor you can read and (on Silverblue) no
xdotool/grim to ask the compositor. So ask the browser instead: this serves one
page that reports its own viewport and screen size back as a request, which
lands in this server's log.

Run it on a machine the kiosk can reach:

    python3 dim-probe.py            # listens on 0.0.0.0:8099

then point the kiosk at it for a moment:

    sudo KIOSK_URL=http://<this-host>:8099/ sh install-kiosk.sh
    sudo pkill -u kiosk firefox        # the kiosk loop reloads and relaunches

`innerWidth == screen.width` and `fullscreenElement == null` is the signature of
a real fullscreen window: the page occupies the whole output, so there is no
browser chrome and no panel left over to measure. (Firefox does not report
itself as a document.fullscreenElement when the window is fullscreen at
startup — that API is for in-page requestFullscreen.)

Read-only, no dependencies, ctrl-C to stop.
"""

from __future__ import annotations

import http.server
import socketserver
import sys
import time

PORT = int(sys.argv[1]) if len(sys.argv) > 1 else 8099

PAGE = b"""<!doctype html><html><head><meta charset="utf-8"><title>dim-probe</title></head>
<body style="margin:0;background:#0a0f14;color:#4fd1c5;font:700 8vmin system-ui">
<div id="t">dim-probe</div>
<script>
function report(tag) {
  const q = new URLSearchParams({
    tag: tag,
    inner: window.innerWidth + "x" + window.innerHeight,
    outer: window.outerWidth + "x" + window.outerHeight,
    screen: screen.width + "x" + screen.height,
    avail: screen.availWidth + "x" + screen.availHeight,
    dpr: window.devicePixelRatio,
    fsElement: document.fullscreenElement ? document.fullscreenElement.tagName : "null",
    ua: encodeURIComponent(navigator.userAgent.slice(0, 40)),
  });
  new Image().src = "/d?" + q.toString();
}
report("load");
// Two more samples: if the window is still settling, the numbers move.
setTimeout(() => report("t2s"), 2000);
setTimeout(() => report("t6s"), 6000);
setInterval(() => report("poll"), 10000);
</script>
</body></html>
"""

PNG1x1 = bytes.fromhex(
    "89504e470d0a1a0a0000000d49484452000000010000000108060000001f15c489"
    "0000000d4944415478da6360000002000100fdff03fd0000000049454e44ae426082"
)


class Handler(http.server.BaseHTTPRequestHandler):
    def do_GET(self) -> None:
        if self.path.startswith("/d?"):
            query = self.path.split("?", 1)[1]
            fields = dict(kv.split("=", 1) for kv in query.split("&") if "=" in kv)
            print(
                f"{time.strftime('%H:%M:%S')} "
                f"{self.client_address[0]:<15} "
                f"{fields.get('tag', '?'):<5} "
                f"viewport={fields.get('inner', '?'):<11} "
                f"window={fields.get('outer', '?'):<11} "
                f"screen={fields.get('screen', '?'):<11} "
                f"available={fields.get('avail', '?'):<11} "
                f"fsElement={fields.get('fsElement', '?')}",
                flush=True,
            )
            self.send_response(200)
            self.send_header("Content-Type", "image/png")
            self.send_header("Cache-Control", "no-store")
            self.send_header("Content-Length", str(len(PNG1x1)))
            self.end_headers()
            self.wfile.write(PNG1x1)
            return

        self.send_response(200)
        self.send_header("Content-Type", "text/html; charset=utf-8")
        self.send_header("Cache-Control", "no-store")
        self.send_header("Content-Length", str(len(PAGE)))
        self.end_headers()
        self.wfile.write(PAGE)

    def log_message(self, *args: object) -> None:
        """Silence the default access log; the /d beacon above is the signal."""


if __name__ == "__main__":
    socketserver.TCPServer.allow_reuse_address = True
    with socketserver.ThreadingTCPServer(("0.0.0.0", PORT), Handler) as httpd:
        print(f"dim-probe on http://0.0.0.0:{PORT}/ — waiting for the kiosk…", flush=True)
        try:
            httpd.serve_forever()
        except KeyboardInterrupt:
            sys.exit(0)