/* Drawings must look the same on every screen.
 *
 * Strokes are stored as vectors in a fixed 1200x1600 page space, so the same
 * note rendered at different viewport widths should differ only by rasterising
 * error. Each rendering is reduced to a coarse ink grid and compared cell by
 * cell, which ignores antialiasing but catches a stroke that moved or vanished.
 *
 * The second thing checked here is the bug that started all of this: the 6-second
 * poller adopting a server response that was issued before the local save, which
 * made strokes disappear again seconds after being drawn. */
import {
  OUT,
  check,
  createNote,
  createNotebook,
  launch,
  reopenNote,
  report,
  setTitle,
  withFreshUser,
} from "./lib.mjs";

const GRID_W = 48,
  GRID_H = 64;

/** Rasterises the drawing surface into a GRID_W x GRID_H map of "has ink". */
const inkGrid = (page) =>
  page.evaluate(
    ([gw, gh]) => {
      const c = document.querySelector("canvas");
      if (!c) return null;
      const off = document.createElement("canvas");
      off.width = gw;
      off.height = gh;
      const ctx = off.getContext("2d", { willReadFrequently: true });
      ctx.drawImage(c, 0, 0, gw, gh);
      const d = ctx.getImageData(0, 0, gw, gh).data;
      const out = [];
      for (let i = 0; i < gw * gh; i++) out.push(d[i * 4 + 3] > 40 ? 1 : 0);
      return out;
    },
    [GRID_W, GRID_H]
  );

const diff = (a, b) => a.reduce((n, v, i) => n + (v === b[i] ? 0 : 1), 0);
const ink = (g) => g.reduce((n, v) => n + v, 0);

async function draw(page) {
  await page.locator("button").filter({ hasText: "Draw" }).first().click();
  await page.waitForTimeout(1200);
  const box = await page.locator("canvas").first().boundingBox();
  // Three strokes in different parts of the page, so a shifted origin shows up.
  const strokes = [
    [0.2, 0.2, 0.7, 0.35],
    [0.25, 0.55, 0.75, 0.5],
    [0.5, 0.7, 0.55, 0.85],
  ];
  for (const [x1, y1, x2, y2] of strokes) {
    await page.mouse.move(box.x + box.width * x1, box.y + box.height * y1);
    await page.mouse.down();
    await page.mouse.move(box.x + box.width * x2, box.y + box.height * y2, { steps: 14 });
    await page.mouse.up();
    await page.waitForTimeout(300);
  }
  await page.waitForTimeout(2500);
  return box;
}

const browser = await launch();
let session;
try {
  session = await withFreshUser(browser, "draw");
  const p = session.page;
  await createNotebook(p, "Zeichen Buch");
  await createNote(p);
  await setTitle(p, "Zeichnung");

  await draw(p);
  const reference = await inkGrid(p);
  check(reference !== null && ink(reference) > 0, "strokes were drawn", `${ink(reference || [])} ink cells`);
  await p.screenshot({ path: `${OUT}/drawing-1400.png` });

  /* ── the poller must not undo what was just drawn ── */
  await p.waitForTimeout(14000);
  const afterPolling = await inkGrid(p);
  check(diff(reference, afterPolling) === 0, "strokes survive 14s of background polling", `${diff(reference, afterPolling)} cells changed`);

  /* ── same note, other screen widths ── */
  const noteId = await p.evaluate(async () => {
    const r = await fetch("/api/notes", {
      headers: { Authorization: "Bearer " + localStorage.getItem("inknote_token") },
    });
    return (await r.json())[0].id;
  });

  for (const width of [1000, 700, 420]) {
    await p.setViewportSize({ width, height: 900 });
    await p.waitForTimeout(2500);
    if (width < 768) {
      // Shrinking past the breakpoint leaves the sidebar open as a full-screen
      // overlay, and its backdrop swallows every click. Dismiss it by clicking
      // to the right of the panel, then reopen the note from the list.
      await p.mouse.click(width - 12, 450);
      await p.waitForTimeout(800);
      const row = p.locator(`[data-note-row="${noteId}"]`);
      if (await row.count()) {
        await row.click();
        await p.waitForTimeout(2500);
      }
    }
    const g = await inkGrid(p);
    if (!g) {
      check(false, `drawing visible at ${width}px`);
      continue;
    }
    const d = diff(reference, g);
    const pct = ((d / (GRID_W * GRID_H)) * 100).toFixed(1);
    check(d / (GRID_W * GRID_H) < 0.02, `drawing matches at ${width}px`, `${d} cells, ${pct}%`);
    await p.screenshot({ path: `${OUT}/drawing-${width}.png` });
  }

  /* ── and after a reload ── */
  // A reload lands on the dashboard, which has no note list — reopen by title.
  await p.setViewportSize({ width: 1400, height: 950 });
  await reopenNote(p, "Zeichnung");
  await p.waitForTimeout(2000);
  const afterReload = await inkGrid(p);
  check(afterReload !== null && ink(afterReload) > 0, "the drawing is still there after a reload");
  if (afterReload) {
    const d = diff(reference, afterReload);
    check(d / (GRID_W * GRID_H) < 0.02, "the reloaded drawing matches the original", `${d} cells`);
  }
} catch (e) {
  check(false, "suite ran to the end", e.message);
} finally {
  await session?.cleanup();
  const code = report();
  await browser.close();
  process.exit(code);
}