/**
 * Diagnostic, NOT part of `npm run test:e2e`, macOS only: what an idle
 * Freezmo screen costs the machine on its real display. Headed WebKit and
 * Chromium (Playwright's builds) open each screen and sit still while the
 * probe reads the browser's own CPU time and the GPU time of its processes
 * and of WindowServer (macOS composites every window there, and Core
 * Animation runs WebKit's CSS animations there), against an about:blank
 * baseline and with the scene parked.
 *
 *   npx playwright-core install webkit chromium   # once
 *   node tests/heat-probe.mjs                     # both engines
 *   node tests/heat-probe.mjs webkit              # one engine
 *
 * Unlike tests/bubble-perf.mjs (frame times in a throttled software renderer)
 * this measures the cost itself, at the display's own refresh rate: on a
 * 144Hz screen every running animation is composited 144 times a second.
 * Keep the window in front while it runs (other apps add noise to the
 * WindowServer column). Always exits 0.
 */
import { execFile } from "node:child_process";
import { promisify } from "node:util";
import { chromium, webkit } from "playwright-core";

import { BASE, CHROME, DECK, seed } from "./lib.mjs";

if (process.platform !== "darwin") {
  console.log("heat-probe: macOS only (it reads ps and the IOKit GPU counters).");
  process.exit(0);
}

const run = promisify(execFile);
const SETTLE_MS = 2500;
const SAMPLE_MS = 8000;
const ENGINES = {
  webkit: { launch: () => webkit.launch({ headless: false }), match: "/ms-playwright/webkit-" },
  chromium: { launch: () => chromium.launch({ headless: false, executablePath: CHROME }), match: CHROME.split("/Contents/")[0] },
};
const SCREENS = [
  ["library", "/"],
  ["study", `/deck/${DECK.id}`],
  ["chat", "/chat"],
];

function seconds(text) {
  const [days, clock] = text.includes("-") ? text.split("-") : ["0", text];
  return clock.split(":").reduce((total, part) => total * 60 + Number(part), 0) + Number(days) * 86400;
}

async function processes() {
  const { stdout } = await run("ps", ["-axo", "pid=,time=,command="], { maxBuffer: 64 << 20 });
  const map = new Map();
  for (const line of stdout.split("\n")) {
    const match = line.match(/^\s*(\d+)\s+(\S+)\s+(.*)$/);
    if (match) map.set(Number(match[1]), { cpu: seconds(match[2]), command: match[3] });
  }
  return map;
}

/** Accumulated GPU time per process (ns) — the number Activity Monitor shows. */
async function gpuTimes() {
  const { stdout } = await run("ioreg", ["-r", "-c", "AGXDeviceUserClient", "-l", "-w", "0"], {
    maxBuffer: 256 << 20,
    encoding: "latin1",
  });
  const map = new Map();
  for (const block of stdout.split("+-o AGXDeviceUserClient")) {
    const creator = block.match(/"IOUserClientCreator" = "pid (\d+),/);
    if (!creator) continue;
    let total = 0;
    for (const match of block.matchAll(/"accumulatedGPUTime"=(\d+)/g)) total += Number(match[1]);
    map.set(Number(creator[1]), (map.get(Number(creator[1])) ?? 0) + total);
  }
  return map;
}

async function measure(match) {
  const [cpu0, gpu0] = [await processes(), await gpuTimes()];
  const start = Date.now();
  await new Promise((resolve) => setTimeout(resolve, SAMPLE_MS));
  const [cpu1, gpu1] = [await processes(), await gpuTimes()];
  const elapsed = (Date.now() - start) / 1000;
  const owner = (pid) => {
    const command = cpu1.get(pid)?.command ?? "";
    return command.includes(match) ? "browser" : command.includes("WindowServer") ? "windowServer" : null;
  };
  const total = { browserCpu: 0, browserGpu: 0, windowServerGpu: 0 };
  for (const [pid, after] of cpu1) {
    const before = cpu0.get(pid);
    if (before && owner(pid) === "browser") total.browserCpu += after.cpu - before.cpu;
  }
  for (const [pid, after] of gpu1) {
    const before = gpu0.get(pid);
    if (before === undefined) continue;
    if (owner(pid) === "browser") total.browserGpu += (after - before) / 1e6;
    if (owner(pid) === "windowServer") total.windowServerGpu += (after - before) / 1e6;
  }
  return {
    cpu: (total.browserCpu / elapsed) * 100,
    gpu: total.browserGpu / elapsed,
    windowServer: total.windowServerGpu / elapsed,
  };
}

const wanted = process.argv.slice(2);
for (const [name, engine] of Object.entries(ENGINES)) {
  if (wanted.length && !wanted.includes(name)) continue;
  const browser = await engine.launch();
  const runs = [["baseline", null, null, false]];
  for (const theme of ["aero", "dark"]) {
    for (const [screen, path] of SCREENS) runs.push([`${screen} ${theme}`, path, theme, false]);
    runs.push([`library ${theme}, parked`, "/", theme, true]);
  }
  console.log(`\n${name} — browser CPU %, browser GPU ms/s, WindowServer GPU ms/s (${SAMPLE_MS / 1000}s each)`);
  for (const [label, path, theme, parked] of runs) {
    const context = await browser.newContext({ viewport: { width: 1600, height: 1000 } });
    const page = await context.newPage();
    if (path) {
      await seed(page, { decks: [DECK], theme });
      await page.goto(BASE + path, { waitUntil: "load" });
    } else {
      await page.goto("about:blank");
    }
    await page.bringToFront();
    if (parked) {
      await page.evaluate(() => {
        document.hasFocus = () => false;
        window.dispatchEvent(new Event("blur"));
      });
    }
    await page.waitForTimeout(SETTLE_MS);
    const cost = await measure(engine.match);
    console.log(
      `  ${label.padEnd(24)} CPU ${cost.cpu.toFixed(1).padStart(5)}%   GPU ${cost.gpu.toFixed(0).padStart(4)}   WindowServer ${cost.windowServer.toFixed(0).padStart(4)}`,
    );
    await context.close();
  }
  await browser.close();
}