// GPU-versus-CPU test: serves the app with Vite's dev server, opens it in a
// headless Chromium with WebGPU through Playwright, and reads the result of the
// in-page self-test (src/selftest.ts), which compares one step of the WGSL
// kernel with the float64 reference.

import { test } from "node:test";
import assert from "node:assert/strict";
import { fileURLToPath } from "node:url";
import { dirname, join } from "node:path";
import { createServer } from "vite";
import { chromium, type Page } from "playwright";

const root = join(dirname(fileURLToPath(import.meta.url)), "..");

interface SelfTestCase {
  name: string;
  accError: { u: number; v: number; w: number };
  positionError: number;
  nodes: number;
  dt: number;
}
interface SelfTestResult { done: boolean; passed?: boolean; cases?: SelfTestCase[]; error?: string }

interface Status {
  phase: string;
  t: number;
  totalSteps: number;
  wmax: number;
  peakPressure: number;
  samples: number;
  frames: number;
  stepsPerSec: number;
  dt: number;
  nx: number;
  ny: number;
  stick: { maxForce: number } | null;
}

const ARGS = ["--enable-unsafe-webgpu", "--enable-features=Vulkan", "--use-angle=vulkan", "--ignore-gpu-blocklist", "--no-sandbox"];

/** Serves the app and opens `query` in a headless Chromium; `body` gets the page and the list of page errors. */
async function withPage(query: string, body: (page: Page, errors: string[]) => Promise<void>): Promise<void> {
  const server = await createServer({ root, logLevel: "silent", server: { port: 0, strictPort: false } });
  await server.listen();
  const url = server.resolvedUrls?.local[0];
  assert.ok(url, "dev server URL");
  const browser = await chromium.launch({ headless: true, args: ARGS });
  try {
    const page = await browser.newPage();
    const errors: string[] = [];
    page.on("pageerror", (e) => errors.push(e.message));
    page.on("console", (msg) => { if (msg.type() === "error" || msg.type() === "warning") errors.push(`console.${msg.type()}: ${msg.text()}`); });
    await page.goto(`${url}?${query}`);
    await body(page, errors);
  } finally {
    await browser.close();
    await server.close();
  }
}

test("one GPU step matches the float64 reference on flat, bowed, and elliptical sheets", { timeout: 120_000 }, async () => {
  await withPage("selftest=1", async (page, errors) => {
    let result: SelfTestResult = { done: false };
    for (let i = 0; i < 120 && !result.done; i++) {
      await page.waitForTimeout(500);
      result = await page.evaluate<SelfTestResult>("window.steelsim ? window.steelsim.selftest() : { done: false }");
    }
    assert.deepEqual(errors, [], "page errors");
    assert.ok(result.done, "self-test did not finish");
    assert.equal(result.error, undefined, `self-test error: ${result.error}`);
    for (const c of result.cases ?? []) {
      console.log(`  ${c.name}: ${c.nodes} nodes, dt ${(c.dt * 1e6).toFixed(2)} us, acc errors ${c.accError.u.toExponential(1)} / ${c.accError.v.toExponential(1)} / ${c.accError.w.toExponential(1)}, position ${c.positionError.toExponential(1)}`);
    }
    assert.ok(result.passed, `self-test failed: ${JSON.stringify(result.cases)}`);
  });
});

/** Runs a short simulation to completion and returns its final status. */
async function runToCompletion(query: string): Promise<Status> {
  let st: Status | null = null;
  await withPage(`autostart=1&${query}`, async (page, errors) => {
    for (let i = 0; i < 600; i++) {
      await page.waitForTimeout(250);
      st = await page.evaluate<Status | null>("window.steelsim ? window.steelsim.status() : null");
      const noGpu = await page.evaluate<string | null>("window.steelsim.noGpu()");
      assert.equal(noGpu, null, `no WebGPU: ${noGpu}`);
      if (st && st.phase === "done") break;
    }
    assert.deepEqual(errors, [], "page errors");
  });
  assert.ok(st, "no status");
  return st!;
}

test("a short push-and-release run completes with finite output", { timeout: 180_000 }, async () => {
  const st = await runToCompletion("spacing=0.012&duration=0.2&rampTime=0.05&holdMax=0.1");
  console.log(`  push: ${st.nx}x${st.ny}, dt ${(st.dt * 1e6).toFixed(2)} us, ${(st.stepsPerSec / 1e3).toFixed(0)} k steps/s, peak ${st.peakPressure.toFixed(3)} Pa, max |w| ${(st.wmax * 1e3).toFixed(2)} mm`);
  assert.equal(st.phase, "done");
  assert.ok(st.samples >= 0.2 * 48000 - 1, "recorded the requested duration");
  assert.ok(isFinite(st.wmax) && st.wmax < 0.05, "displacement stays bounded");
  assert.ok(st.peakPressure > 1e-3 && isFinite(st.peakPressure), "the sheet radiates");
});

test("a short drumstick strike on an elliptical sheet completes with finite output", { timeout: 180_000 }, async () => {
  const st = await runToCompletion("spacing=0.012&duration=0.2&excitation=strike&shape=ellipse");
  console.log(`  strike: ${st.nx}x${st.ny}, ${(st.stepsPerSec / 1e3).toFixed(0)} k steps/s, peak ${st.peakPressure.toFixed(3)} Pa, max contact force ${st.stick?.maxForce.toFixed(1)} N`);
  assert.equal(st.phase, "done");
  assert.ok(isFinite(st.wmax) && st.wmax < 0.05, "displacement stays bounded");
  assert.ok(st.peakPressure > 1e-3, "the sheet radiates");
  assert.ok(st.stick && st.stick.maxForce > 1, "the stick hit the sheet");
});