"""ZERO-DOM acceptance test via headless Chrome.

1. asserts the served page has NO DOM UI (no div/img/button/input/span), only
   the single framebuffer <canvas>;
2. screenshots the running OS and asserts real pixels were produced (the page
   is not black, and a Luna-blue taskbar band exists at the bottom).
"""
import os
import re
import subprocess
import sys
import time
import urllib.request
import json

CHROME = r"C:\Program Files\Google\Chrome\Application\chrome.exe"
PORT = 7866
BASE = f"http://127.0.0.1:{PORT}"
HERE = os.path.dirname(os.path.abspath(__file__))


def wait_up():
    for _ in range(80):
        try:
            with urllib.request.urlopen(f"{BASE}/healthz", timeout=2) as r:
                json.loads(r.read())
                return True
        except Exception:
            time.sleep(0.25)
    return False


def chrome(args, timeout=60):
    cmd = [CHROME, "--headless=new", "--no-first-run", "--no-default-browser-check",
           "--disable-gpu", "--hide-scrollbars",
           "--user-data-dir=" + os.path.join(HERE, ".chrome-test"), *args]
    return subprocess.run(cmd, capture_output=True, text=True, timeout=timeout)


def main():
    env = dict(os.environ, NEURALOS_ENGINE="mock", PORT=str(PORT),
               NEURALOS_CACHE="/tmp/neuralos_dom_cache")
    proc = subprocess.Popen([sys.executable, "app.py"], env=env,
                            stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    try:
        assert wait_up(), "server did not start"

        # ---- 1. DOM audit ----
        dom = chrome(["--dump-dom", "--virtual-time-budget=6000", BASE]).stdout
        # strip <script>/<style> bodies so JS comments/strings can't be miscounted
        markup = re.sub(r"<style.*?</style>", "", dom, flags=re.S | re.I)
        markup = re.sub(r"<script.*?</script>", "", markup, flags=re.S | re.I)
        counts = {tag: len(re.findall(rf"<\s*{tag}\b", markup, re.I))
                  for tag in ("canvas", "div", "img", "button", "input", "span", "svg", "iframe", "a")}
        print("DOM tag counts (markup only):", counts)
        assert counts["canvas"] == 1, f"expected exactly one canvas element, got {counts['canvas']}"
        for tag in ("div", "img", "button", "input", "span", "svg", "iframe"):
            assert counts[tag] == 0, f"ZERO-DOM violated: found <{tag}>"

        body = re.search(r"<body[^>]*>(.*)</body>", markup, re.S | re.I)
        inner = body.group(1) if body else markup
        inner = re.sub(r"<canvas[^>]*>\s*</canvas>", "", inner, flags=re.S | re.I)
        assert inner.strip() == "", f"unexpected DOM content: {inner[:200]!r}"
        print("ZERO-DOM: body contains only one canvas and no other elements")

        # ---- 2. render audit ----
        shot = os.path.join(HERE, "zerodom_shot.png")
        if os.path.exists(shot):
            os.remove(shot)
        chrome([f"--screenshot={shot}", "--window-size=1000,1000",
                "--virtual-time-budget=8000", BASE])
        assert os.path.exists(shot), "no screenshot produced"

        from PIL import Image
        import numpy as np
        img = Image.open(shot).convert("RGB")
        a = np.asarray(img)
        nonblack = (a.sum(axis=2) > 30).mean()
        bottom = a[int(a.shape[0] * 0.93):, :, :]
        blueish = ((bottom[:, :, 2].astype(int) > bottom[:, :, 0].astype(int) + 25)).mean()
        print(f"screenshot {img.size}, non-black {nonblack:.1%}, bottom-blue {blueish:.1%}")
        assert nonblack > 0.5, "framebuffer looks blank"
        assert blueish > 0.3, "no Luna-blue taskbar band rendered"
        print("RENDER OK: pixels produced, taskbar present")
        print("ZERO-DOM E2E OK")
    finally:
        proc.terminate()
        try:
            proc.wait(10)
        except Exception:
            proc.kill()


if __name__ == "__main__":
    main()