// Ground-truth annotation canvas, one instance per <div class="gt-root"
// data-key="..." data-multi="0|1">.
//
// Everything after segmentation happens in the browser: hit-testing, drawing,
// undo, the min-size filter and the count. The server is only called to run
// Cellpose, so no click ever round-trips an image or shows a progress bar.
//
// The server hands over, per square, the warped square (JPEG) and a label PNG
// whose R,G channels hold the 16-bit object id and whose B channel holds each
// pixel's distance, in px, to the object's edge. The distance lets the outline
// thickness follow the zoom level without recomputing anything.
//
// Single mode (data-multi="0"): the instance also does the 4-corner step
// before segmentation. Multi mode (data-multi="1"): up to 4 squares, switched
// with buttons or keys 1-4, plus a results table and a copyable TSV row.
(function () {
  "use strict";

  const LEFT_PCT = 1;        // exclusion zone on the LEFT edge, % of width
  const BOTTOM_PCT = 1;      // exclusion zone on the BOTTOM edge, % of height
  const RING_SCREEN_PX = 3;  // outline thickness on screen, whatever the zoom
  const DOT_R = 6;           // added-dot radius, screen px
  const DOT_HIT_PX = 9;      // a click this close to a dot (screen px) hits it
  const CORNER_HIT_PX = 12;  // ditto for corner handles
  const DRAG_PX = 4;         // movement beyond this turns a click into a pan
  const MAX_ZOOM = 40;
  const COUNTED = 0, REMOVED = 1, SMALL = 2, EXCLUDED = 3, ABSENT = 4;

  const INST = {};           // key -> instance
  const PENDING = {};        // key -> payload that arrived before mounting

  // ================================================================ instance
  function create(root) {
    const S = {
      key: root.dataset.key, multi: root.dataset.multi === "1",
      mode: "empty",           // "empty" | "corners" | "annotate"
      seq: null, view: { s: 1, tx: 0, ty: 0 },
      cimg: null, cW: 0, cH: 0, cscale: 1, corners: [],
      sets: [], cur: -1, d: null, minSize: 0,
      hover: null, hoverCanvas: null, hoverId: 0,
      hideOverlay: false, pointerIn: false,
      down: null, dragCorner: -1, panning: false,
      dirty: true, ringDirty: false, warn: "",
      t0: null, segTime: null, serverTime: null, stamp: "",
    };
    const q = (c) => root.querySelector(".gt-" + c);
    const el = {};
    for (const n of ["total", "breakdown", "min", "minnum", "undo", "redo",
                     "fit", "resetc", "editc", "hint", "empty", "stage",
                     "sq", "results", "canvas"]) el[n] = q(n);
    const cv = el.canvas, ctx = cv.getContext("2d");
    S.root = root;

    cv.addEventListener("pointerdown", onDown);
    cv.addEventListener("pointermove", onMove);
    cv.addEventListener("pointerup", onUp);
    cv.addEventListener("pointercancel", onUp);
    cv.addEventListener("pointerenter", () => { S.pointerIn = true; });
    cv.addEventListener("pointerleave", () => {
      S.pointerIn = false; S.hover = null; dirty();
    });
    cv.addEventListener("wheel", onWheel, { passive: false });
    cv.addEventListener("contextmenu", (e) => e.preventDefault());
    el.min.addEventListener("input", () => setMin(+el.min.value));
    el.minnum.addEventListener("input", () => setMin(+el.minnum.value || 0));
    el.undo.addEventListener("click", undo);
    el.redo.addEventListener("click", redo);
    el.fit.addEventListener("click", () => { fit(); dirty(); });
    el.resetc.addEventListener("click", resetCorners);
    el.editc.addEventListener("click", backToCorners);
    if (el.results) {
      el.results.addEventListener("click", (e) => {
        const b = e.target.closest("button[data-copy]");
        if (b) copyRow(b.dataset.copy === "header", b);
      });
    }
    new ResizeObserver(() => { sizeCanvas(); dirty(); }).observe(el.stage);
    sizeCanvas();

    // ---------------------------------------------------------- setup
    function sizeCanvas() {
      const dpr = window.devicePixelRatio || 1;
      const w = el.stage.clientWidth, h = el.stage.clientHeight;
      if (!w || !h) return;
      const first = !cv.width || cv.width === 300;
      cv.width = Math.round(w * dpr); cv.height = Math.round(h * dpr);
      if (first || !S.fitted) fit();
    }

    // ---------------------------------------------------------- loading
    async function load(p) {
      if (p.seq && p.seq === S.seq) return;
      S.seq = p.seq;
      if (p.mode === "corners") {
        S.cimg = await loadImage(p.img);
        S.cW = p.w; S.cH = p.h; S.cscale = p.scale;
        S.corners = []; S.sets = []; S.cur = -1; S.d = null;
        S.mode = "corners"; S.fitted = false;
        fit();
      } else if (p.mode === "annotate") {
        S.sets = [await makeSet(p)]; S.serverTime = null;
        switchTo(0);
        S.mode = "annotate";
      } else if (p.mode === "annotate4") {
        const sets = await Promise.all(
          p.squares.map((sq) => (sq ? makeSet(sq) : Promise.resolve(null))));
        S.sets = sets; S.mode = "annotate";
        S.serverTime = p.server_secs;
        const t = new Date(), z = (v) => String(v).padStart(2, "0");
        S.stamp = t.getFullYear() + "-" + z(t.getMonth() + 1) + "-" + z(t.getDate()) +
                  " " + z(t.getHours()) + ":" + z(t.getMinutes()) + ":" + z(t.getSeconds());
        S.segTime = S.t0 != null ? (performance.now() - S.t0) / 1000 : null;
        S.t0 = null;
        const first = sets.findIndex((d) => d);
        if (first >= 0) switchTo(first);
        else { S.mode = "empty"; S.d = null; }
        S.note = p.note || "";
      }
      updateUI(); dirty();
    }

    async function makeSet(p) {
      const [img, px] = await Promise.all([loadImage(p.img),
                                           decodeLabels(p.lab, p.w, p.h)]);
      const W = p.w, H = p.h, N = W * H;
      const lab = new Uint16Array(N), dist = new Uint8Array(N);
      let maxId = 0;
      for (let i = 0, o = 0; i < N; i++, o += 4) {
        const id = (px[o] << 8) | px[o + 1];
        lab[i] = id; dist[i] = px[o + 2];
        if (id > maxId) maxId = id;
      }
      const n = maxId + 1;
      const area = new Int32Array(n);
      const minx = new Int32Array(n).fill(W), miny = new Int32Array(n).fill(H);
      const maxx = new Int32Array(n).fill(-1), maxy = new Int32Array(n).fill(-1);
      const sumx = new Float64Array(n), sumy = new Float64Array(n);
      for (let y = 0, i = 0; y < H; y++) {
        for (let x = 0; x < W; x++, i++) {
          const id = lab[i];
          if (!id) continue;
          area[id]++; sumx[id] += x; sumy[id] += y;
          if (x < minx[id]) minx[id] = x;
          if (x > maxx[id]) maxx[id] = x;
          if (y < miny[id]) miny[id] = y;
          if (y > maxy[id]) maxy[id] = y;
        }
      }
      const overlay = document.createElement("canvas");
      overlay.width = W; overlay.height = H;
      const octx = overlay.getContext("2d");
      return {
        name: p.name || "", img, W, H, lab, dist, nobj: p.nobj,
        area, minx, miny, maxx, maxy,
        cx: sumx.map((v, i) => area[i] ? v / area[i] + 0.5 : 0),
        cy: sumy.map((v, i) => area[i] ? v / area[i] + 0.5 : 0),
        status: new Uint8Array(n), removed: new Uint8Array(n),
        colors: makeColors(n), dots: [], undo: [], redo: [],
        overlay, octx, oimg: octx.createImageData(W, H), tImg: -1,
        ovMin: -1, view: null,
        warn: maxId !== p.nobj ? "Label decode mismatch (" + maxId + " vs " +
              p.nobj + " objects) - counts may be off. Try another browser." : "",
      };
    }

    function switchTo(k) {
      const D = S.sets[k];
      if (!D) return;
      if (S.d) S.d.view = S.view;
      S.cur = k; S.d = D; S.hover = null; S.hoverId = 0;
      if (D.view) S.view = D.view; else { S.view = { s: 1, tx: 0, ty: 0 }; fitTo(D.W, D.H); }
      computeAllStatus(D);
      if (D.ovMin !== S.minSize || D.tImg !== ringT()) rebuildOverlay();
      updateUI(); dirty();
    }

    // ---------------------------------------------------------- status
    function statusOf(D, id) {
      if (!D.area[id]) return ABSENT;
      if (D.area[id] < S.minSize) return SMALL;
      const leftPx = Math.floor(D.W * LEFT_PCT / 100);
      const botPx = Math.floor(D.H * BOTTOM_PCT / 100);
      if (D.minx[id] < leftPx || D.maxy[id] >= D.H - botPx) return EXCLUDED;
      return D.removed[id] ? REMOVED : COUNTED;
    }

    function computeAllStatus(D) {
      for (let id = 1; id < D.status.length; id++) D.status[id] = statusOf(D, id);
    }

    function counts(D) {
      const c = [0, 0, 0, 0];
      for (let id = 1; id < D.status.length; id++) {
        const st = D.status[id];
        if (st < 4) c[st]++;
      }
      // model = what Cellpose counted (after min size + exclusion), before edits
      return { counted: c[0], removed: c[1], small: c[2], excl: c[3],
               added: D.dots.length, model: c[0] + c[1],
               total: c[0] + D.dots.length };
    }

    // ---------------------------------------------------------- overlay
    function ringT() {
      return Math.max(1, Math.min(12, Math.round(RING_SCREEN_PX / S.view.s)));
    }

    function paint(D, i, d) {
      const id = D.lab[i], o = i * 4;
      if (!id) { d[o + 3] = 0; return; }
      const st = D.status[id], dd = D.dist[i], t = D.tImg;
      const edge = dd <= 1 && t >= 2;          // 1 px black separator
      if (st === COUNTED) {
        if (edge) { d[o] = d[o + 1] = d[o + 2] = 0; d[o + 3] = 255; return; }
        d[o] = D.colors[id * 3]; d[o + 1] = D.colors[id * 3 + 1];
        d[o + 2] = D.colors[id * 3 + 2];
        d[o + 3] = dd <= t ? 255 : 40;
      } else if (st === REMOVED) {
        if (edge) { d[o] = d[o + 1] = d[o + 2] = 0; d[o + 3] = 255; return; }
        d[o] = 235; d[o + 1] = 30; d[o + 2] = 30;
        d[o + 3] = dd <= t ? 255 : 105;
      } else if (st === SMALL) {
        const on = dd <= Math.max(1, t - 1);
        d[o] = d[o + 1] = d[o + 2] = 150; d[o + 3] = on ? 230 : 0;
      } else if (st === EXCLUDED) {
        const on = dd <= Math.max(1, t - 1);
        d[o] = d[o + 1] = d[o + 2] = 255; d[o + 3] = on ? 150 : 0;
      } else {
        d[o + 3] = 0;
      }
    }

    function rebuildOverlay() {
      const D = S.d;
      if (!D) return;
      D.tImg = ringT(); D.ovMin = S.minSize;
      const d = D.oimg.data, N = D.W * D.H;
      for (let i = 0; i < N; i++) paint(D, i, d);
      D.octx.putImageData(D.oimg, 0, 0);
      S.hoverId = 0;
      dirty();
    }

    function repaintObject(id) {
      const D = S.d, d = D.oimg.data, W = D.W;
      const x0 = D.minx[id], x1 = D.maxx[id], y0 = D.miny[id], y1 = D.maxy[id];
      if (x1 < 0) return;
      for (let y = y0; y <= y1; y++) {
        for (let x = x0, i = y * W + x0; x <= x1; x++, i++) {
          if (D.lab[i] === id) paint(D, i, d);
        }
      }
      D.octx.putImageData(D.oimg, 0, 0, x0, y0, x1 - x0 + 1, y1 - y0 + 1);
    }

    function hoverOutline(id) {
      if (S.hoverId === id && S.hoverCanvas) return S.hoverCanvas;
      const D = S.d, x0 = D.minx[id], y0 = D.miny[id];
      const w = D.maxx[id] - x0 + 1, h = D.maxy[id] - y0 + 1;
      const c = document.createElement("canvas");
      c.width = w; c.height = h;
      const x = c.getContext("2d"), im = x.createImageData(w, h), d = im.data;
      const t = Math.max(1, D.tImg) + 1;
      for (let yy = 0; yy < h; yy++) {
        for (let xx = 0; xx < w; xx++) {
          const i = (y0 + yy) * D.W + x0 + xx, o = (yy * w + xx) * 4;
          if (D.lab[i] !== id) continue;
          d[o] = d[o + 1] = d[o + 2] = 255;
          d[o + 3] = D.dist[i] <= t ? 255 : 70;
        }
      }
      x.putImageData(im, 0, 0);
      S.hoverCanvas = c; S.hoverId = id;
      return c;
    }

    // ---------------------------------------------------------- view
    function curSize() {
      if (S.mode === "corners") return [S.cW, S.cH];
      if (S.mode === "annotate" && S.d) return [S.d.W, S.d.H];
      return [0, 0];
    }

    function fitTo(w, h) {
      const cw = el.stage.clientWidth, ch = el.stage.clientHeight;
      if (!w || !cw || !ch) return;
      const s = Math.min(cw / w, ch / h) * 0.96;
      S.view = { s, tx: (cw - w * s) / 2, ty: (ch - h * s) / 2 };
      S.fitted = true;
    }

    function fit() {
      const [w, h] = curSize();
      fitTo(w, h);
      if (S.mode === "annotate" && S.d && ringT() !== S.d.tImg) rebuildOverlay();
    }

    const toImg = (sx, sy) => [(sx - S.view.tx) / S.view.s, (sy - S.view.ty) / S.view.s];
    const toScreen = (ix, iy) => [ix * S.view.s + S.view.tx, iy * S.view.s + S.view.ty];
    function evPos(e) {
      const r = cv.getBoundingClientRect();
      return [e.clientX - r.left, e.clientY - r.top];
    }
    const clamp = (v, a, b) => Math.max(a, Math.min(b, v));

    function onWheel(e) {
      const [w, h] = curSize();
      if (!w) return;
      e.preventDefault();
      const [sx, sy] = evPos(e);
      const fitS = Math.min(el.stage.clientWidth / w, el.stage.clientHeight / h);
      const s = clamp(S.view.s * Math.pow(1.0015, -e.deltaY), fitS * 0.5, MAX_ZOOM);
      const [ix, iy] = toImg(sx, sy);
      S.view = { s, tx: sx - ix * s, ty: sy - iy * s };
      if (S.mode === "annotate" && S.d && ringT() !== S.d.tImg) S.ringDirty = true;
      refreshHover(sx, sy, e.shiftKey);
      dirty();
    }

    // ---------------------------------------------------------- pointer
    function onDown(e) {
      if (S.mode === "empty") return;
      cv.setPointerCapture(e.pointerId);
      root.focus({ preventScroll: true });
      const [sx, sy] = evPos(e);
      S.down = { sx, sy, tx: S.view.tx, ty: S.view.ty, button: e.button };
      S.panning = e.button !== 0;
      S.dragCorner = S.mode === "corners" && e.button === 0 ? cornerAt(sx, sy) : -1;
    }

    function onMove(e) {
      const [sx, sy] = evPos(e);
      if (!S.down) { refreshHover(sx, sy, e.shiftKey); return; }
      const dx = sx - S.down.sx, dy = sy - S.down.sy;
      if (S.dragCorner >= 0) {
        const [ix, iy] = toImg(sx, sy);
        S.corners[S.dragCorner] = [clamp(ix, 0, S.cW - 1), clamp(iy, 0, S.cH - 1)];
        updateUI(); dirty();
        return;
      }
      if (!S.panning && Math.hypot(dx, dy) > DRAG_PX) S.panning = true;
      if (S.panning) {
        S.view.tx = S.down.tx + dx; S.view.ty = S.down.ty + dy;
        S.hover = null; dirty();
      }
    }

    function onUp(e) {
      if (!S.down) return;
      const [sx, sy] = evPos(e);
      const wasPan = S.panning, wasCorner = S.dragCorner >= 0, b = S.down.button;
      S.down = null; S.panning = false; S.dragCorner = -1;
      if (e.type === "pointercancel" || wasPan || wasCorner || b !== 0) {
        refreshHover(sx, sy, e.shiftKey);
        return;
      }
      if (S.mode === "corners") cornerClick(sx, sy);
      else if (S.mode === "annotate" && S.d) {
        const a = hitTest(sx, sy, e.shiftKey);
        if (a) { exec(a); S.d.undo.push(a); S.d.redo = []; afterEdit(); }
        refreshHover(sx, sy, e.shiftKey);
      }
    }

    // ---------------------------------------------------------- corners
    function cornerAt(sx, sy) {
      let best = -1, bd = CORNER_HIT_PX;
      S.corners.forEach(([x, y], k) => {
        const [px, py] = toScreen(x, y);
        const d = Math.hypot(px - sx, py - sy);
        if (d <= bd) { bd = d; best = k; }
      });
      return best;
    }

    function cornerClick(sx, sy) {
      if (S.corners.length >= 4) {
        hint("All 4 corners placed: drag a handle to adjust, or press Reset " +
             "corners. Then press Segment.");
        return;
      }
      const [ix, iy] = toImg(sx, sy);
      if (ix < 0 || iy < 0 || ix >= S.cW || iy >= S.cH) return;
      S.corners.push([ix, iy]);
      updateUI(); dirty();
    }

    function resetCorners() {
      if (S.mode !== "corners") return;
      S.corners = []; updateUI(); dirty();
    }

    function backToCorners() {
      if (S.mode !== "annotate" || !S.cimg) return;
      if (S.d) S.d.view = S.view;
      S.mode = "corners"; S.fitted = false; fit(); updateUI(); dirty();
    }

    function orderedCorners() {
      const c = S.corners;
      if (c.length !== 4) return c;
      const mx = c.reduce((a, p) => a + p[0], 0) / 4;
      const my = c.reduce((a, p) => a + p[1], 0) / 4;
      const o = c.slice().sort((a, b) => Math.atan2(a[1] - my, a[0] - mx) -
                                         Math.atan2(b[1] - my, b[0] - mx));
      let k = 0;
      o.forEach((p, i) => { if (p[0] + p[1] < o[k][0] + o[k][1]) k = i; });
      return o.slice(k).concat(o.slice(0, k));
    }

    function editCount() {
      return S.sets.reduce((a, D) => a + (D ? D.undo.length : 0), 0);
    }

    function confirmDiscard() {
      const n = editCount();
      return !n || window.confirm("Re-segmenting discards your " + n +
                                  " edit(s). Continue?");
    }

    function getCorners() {
      if (S.mode === "annotate") {
        if (!confirmDiscard()) return "CANCEL";
        if (S.cimg) { S.mode = "corners"; S.fitted = false; fit(); }
      }
      if (S.mode !== "corners" || S.corners.length !== 4) return "";
      hint("Segmenting...");
      return JSON.stringify(S.corners.map(([x, y]) => [x / S.cscale, y / S.cscale]));
    }

    function markStart() {
      // Multi mode: Segment pressed. Starts the end-to-end timer.
      if (S.mode === "annotate" && !confirmDiscard()) return false;
      S.t0 = performance.now();
      hint("Segmenting 4 squares...");
      if (el.total) el.total.textContent = "…";
      return true;
    }

    // ---------------------------------------------------------- edits
    function hitTest(sx, sy, shift) {
      const D = S.d, [ix, iy] = toImg(sx, sy);
      if (ix < 0 || iy < 0 || ix >= D.W || iy >= D.H) return null;
      if (!shift) {
        // Dots first, tolerance in SCREEN px: zooming in makes it tighter.
        let best = null, bd = DOT_HIT_PX;
        for (const d of D.dots) {
          const [px, py] = toScreen(d.x, d.y);
          const dd = Math.hypot(px - sx, py - sy);
          if (dd <= bd) { bd = dd; best = d; }
        }
        if (best) return { type: "deldot", dot: best };
        // Masks are hit EXACTLY: a click on background between touching
        // cells always adds a dot rather than removing a neighbour.
        const id = D.lab[Math.floor(iy) * D.W + Math.floor(ix)];
        if (id) {
          const st = D.status[id];
          if (st === COUNTED) return { type: "remove", id };
          if (st === REMOVED) return { type: "restore", id };
        }
      }
      return { type: "add", dot: { x: ix, y: iy } };
    }

    function exec(a) {
      const D = S.d;
      if (a.type === "add") D.dots.push(a.dot);
      else if (a.type === "deldot") {
        const k = D.dots.indexOf(a.dot);
        if (k >= 0) D.dots.splice(k, 1);
      } else {
        D.removed[a.id] = a.type === "remove" ? 1 : 0;
        D.status[a.id] = statusOf(D, a.id);
        repaintObject(a.id);
        if (S.hoverId === a.id) S.hoverId = 0;
      }
    }

    function inverse(a) {
      const t = { add: "deldot", deldot: "add", remove: "restore",
                  restore: "remove" }[a.type];
      return Object.assign({}, a, { type: t });
    }

    function undo() {
      if (!S.d) return;
      const a = S.d.undo.pop();
      if (!a) return;
      exec(inverse(a)); S.d.redo.push(a); afterEdit();
    }

    function redo() {
      if (!S.d) return;
      const a = S.d.redo.pop();
      if (!a) return;
      exec(a); S.d.undo.push(a); afterEdit();
    }

    function afterEdit() { updateUI(); dirty(); }

    function setMin(v) {
      v = Math.max(0, Math.round(v || 0));
      S.minSize = v;
      if (+el.min.value !== v) el.min.value = Math.min(v, +el.min.max);
      if (+el.minnum.value !== v) el.minnum.value = v;
      for (const D of S.sets) if (D) computeAllStatus(D);
      if (S.mode === "annotate" && S.d) rebuildOverlay();
      updateUI();
    }

    // ---------------------------------------------------------- hover
    function refreshHover(sx, sy, shift) {
      if (S.mode !== "annotate" || !S.d || !S.pointerIn) { S.hover = null; dirty(); return; }
      const a = hitTest(sx, sy, shift);
      S.hover = a ? Object.assign({ sx, sy }, a) : null;
      if (a) {
        const msg = {
          add: shift ? "Shift+click: add a dot here (even on a cell)"
                     : "Click: add a dot (missed cell)",
          deldot: "Click: delete this dot",
          remove: "Click: remove this cell (" + (a.id ? S.d.area[a.id] : 0) + " px)",
          restore: "Click: restore this removed cell",
        }[a.type];
        hint(msg + "   ·   Shift+click always adds   ·   hold Space " +
             "to hide outlines   ·   Ctrl+Z undo" +
             (S.multi ? "   ·   1-4 switch square" : ""));
      }
      dirty();
    }

    // ---------------------------------------------------------- keys
    function onKey(e) {
      if (S.mode === "empty") return false;
      const mod = e.ctrlKey || e.metaKey;
      if (e.code === "Space") {
        e.preventDefault();
        if (!S.hideOverlay) { S.hideOverlay = true; dirty(); }
      } else if (mod && e.key.toLowerCase() === "z") {
        e.preventDefault(); e.shiftKey ? redo() : undo();
      } else if (mod && e.key.toLowerCase() === "y") {
        e.preventDefault(); redo();
      } else if (e.key === "f" || e.key === "F") {
        fit(); dirty();
      } else if (S.multi && S.mode === "annotate" && /^[1-4]$/.test(e.key) && !mod) {
        switchTo(+e.key - 1);
      } else if (e.key === "Shift" && S.hover) {
        refreshHover(S.hover.sx, S.hover.sy, true);
      }
      return true;
    }

    function onKeyUp(e) {
      if (e.code === "Space" && S.hideOverlay) {
        S.hideOverlay = false; dirty();
      } else if (e.key === "Shift" && S.hover) {
        refreshHover(S.hover.sx, S.hover.sy, false);
      }
    }

    // ---------------------------------------------------------- UI text
    function hint(t) { if (el.hint) el.hint.textContent = t; }

    function tsv(header) {
      const head = ["timestamp", "files"];
      const row = [S.stamp, S.sets.map((D) => (D ? D.name : "")).join(";")];
      const corr = [];
      for (let k = 0; k < 4; k++) {
        const D = S.sets[k];
        const c = D ? counts(D) : null;
        head.push("model_sq" + (k + 1), "corrected_sq" + (k + 1));
        row.push(c ? c.model : "", c ? c.total : "");
        if (c) corr.push(c.total);
      }
      head.push("mean_corrected", "seg_time_s", "server_time_s", "min_size_px");
      row.push(corr.length ? (corr.reduce((a, b) => a + b, 0) / corr.length).toFixed(2) : "",
               S.segTime != null ? S.segTime.toFixed(2) : "",
               S.serverTime != null ? S.serverTime.toFixed(2) : "",
               S.minSize);
      return (header ? head.join("\t") + "\n" : "") + row.join("\t");
    }

    function copyRow(header, btn) {
      const text = tsv(header);
      const done = () => {
        const old = btn.textContent;
        btn.textContent = "✓ Copied"; setTimeout(() => (btn.textContent = old), 1200);
      };
      if (navigator.clipboard && window.isSecureContext) {
        navigator.clipboard.writeText(text).then(done, () => fallbackCopy(text, done));
      } else fallbackCopy(text, done);
    }

    function fallbackCopy(text, done) {
      const ta = document.createElement("textarea");
      ta.value = text; ta.style.position = "fixed"; ta.style.opacity = "0";
      document.body.appendChild(ta); ta.select();
      try { document.execCommand("copy"); done(); } catch (e) { /* ignore */ }
      ta.remove();
    }

    function renderMulti() {
      if (!S.multi) return;
      // square switcher
      el.sq.innerHTML = "";
      S.sets.forEach((D, k) => {
        const b = document.createElement("button");
        b.textContent = "Square " + (k + 1) + (D ? " · " + counts(D).total : " · —");
        b.disabled = !D;
        if (k === S.cur) b.classList.add("gt-cur");
        b.addEventListener("click", () => switchTo(k));
        el.sq.appendChild(b);
      });
      // results table + TSV row
      if (!S.sets.length) { el.results.innerHTML = ""; return; }
      let rows = "";
      let sumM = 0, sumC = 0, n = 0;
      S.sets.forEach((D, k) => {
        if (!D) {
          rows += "<tr><td>" + (k + 1) + "</td><td colspan=6>not segmented</td></tr>";
          return;
        }
        const c = counts(D);
        sumM += c.model; sumC += c.total; n++;
        rows += "<tr" + (k === S.cur ? " class='gt-cur'" : "") + "><td>" + (k + 1) +
                "</td><td class='gt-name'>" + esc(D.name) + "</td><td>" + c.model +
                "</td><td class='gt-r'>&minus;" + c.removed + "</td><td class='gt-a'>+" +
                c.added + "</td><td><b>" + c.total + "</b></td><td>" +
                // count error vs ground truth, as the main app reports it:
                // positive = the model over-counted
                (c.total ? ((c.model - c.total) / c.total * 100 > 0 ? "+" : "") +
                 ((c.model - c.total) / c.total * 100).toFixed(1) + "%" : "") +
                "</td></tr>";
      });
      const mean = n ? "<tr class='gt-mean'><td colspan=2>Mean</td><td>" +
                   (sumM / n).toFixed(1) + "</td><td></td><td></td><td><b>" +
                   (sumC / n).toFixed(1) + "</b></td><td></td></tr>" : "";
      const time = "Segmentation: <b>" +
        (S.segTime != null ? S.segTime.toFixed(2) + " s" : "—") +
        "</b> end-to-end (click → all squares ready)" +
        (S.serverTime != null ? " · server " + S.serverTime.toFixed(2) + " s" : "");
      el.results.innerHTML =
        "<div class='gt-time'>" + time + "</div>" +
        (S.note ? "<div class='gt-r'>" + esc(S.note) + "</div>" : "") +
        "<table><thead><tr><th>Sq</th><th>File</th><th>Model</th><th>Removed</th>" +
        "<th>Added</th><th>Corrected</th><th title=\"(model - corrected) / corrected\">Count error</th></tr></thead><tbody>" +
        rows + mean + "</tbody></table>" +
        "<div class='gt-copy'><input readonly value='" + esc(tsv(false)) + "'>" +
        "<button data-copy='row'>Copy row</button>" +
        "<button data-copy='header'>Copy with header</button></div>";
    }

    function esc(s) {
      return String(s).replace(/[&<>'"]/g, (c) => ({ "&": "&amp;", "<": "&lt;",
        ">": "&gt;", "'": "&#39;", '"': "&quot;" }[c]));
    }

    function updateUI() {
      el.empty.style.display = S.mode === "empty" ? "" : "none";
      el.resetc.style.display = S.mode === "corners" ? "" : "none";
      el.editc.style.display = S.mode === "annotate" && S.cimg ? "" : "none";
      el.undo.disabled = !(S.d && S.d.undo.length);
      el.redo.disabled = !(S.d && S.d.redo.length);
      if (S.mode === "annotate" && S.d) {
        const D = S.d, c = counts(D);
        el.total.textContent = c.total;
        el.breakdown.innerHTML =
          (S.multi ? "<b>Square " + (S.cur + 1) + "</b>: " : "") +
          D.nobj + " detected" +
          (c.small ? " &minus; " + c.small + " below " + S.minSize + " px" : "") +
          (c.excl ? " &minus; " + c.excl + " on exclusion lines" : "") +
          " &minus; <b class='gt-r'>" + c.removed + " removed</b>" +
          " + <b class='gt-a'>" + c.added + " added</b>" +
          (D.warn ? "<br><span class='gt-r'>" + D.warn + "</span>" : "");
        if (!S.hover) {
          hint("Click a cell to remove it · click empty space to add a dot " +
               "· Shift+click always adds · wheel zooms, drag pans " +
               "· hold Space to hide outlines · Ctrl+Z undo · F fit" +
               (S.multi ? " · 1-4 switch square" : ""));
        }
      } else if (S.mode === "corners") {
        el.total.textContent = "—";
        el.breakdown.textContent = S.corners.length + " / 4 corners";
        hint(S.corners.length < 4
          ? "Click corner " + (S.corners.length + 1) + " of the 4×4 block " +
            "(any order) · wheel zooms, drag pans"
          : "Drag any handle to fine-tune, then press Segment.");
      } else if (S.t0 == null) {
        el.total.textContent = "—";
        el.breakdown.textContent = "";
        hint(S.multi ? "Upload 4 images and set their corners above, then " +
                       "press Segment all 4." : "");
      }
      renderMulti();
    }

    // ---------------------------------------------------------- draw
    function dirty() { S.dirty = true; }

    function frame() {
      if (S.ringDirty && !S.down) { S.ringDirty = false; rebuildOverlay(); }
      if (!S.dirty) return;
      S.dirty = false;
      draw();
    }

    function draw() {
      const dpr = window.devicePixelRatio || 1;
      ctx.setTransform(1, 0, 0, 1, 0, 0);
      ctx.fillStyle = "#1b1d22";
      ctx.fillRect(0, 0, cv.width, cv.height);
      if (S.mode === "empty") return;
      const { s, tx, ty } = S.view;
      ctx.setTransform(dpr * s, 0, 0, dpr * s, dpr * tx, dpr * ty);
      ctx.imageSmoothingEnabled = s < 2;

      if (S.mode === "corners") {
        ctx.drawImage(S.cimg, 0, 0);
        ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
        drawCorners();
        return;
      }
      const D = S.d;
      if (!D) return;
      ctx.drawImage(D.img, 0, 0);
      if (!S.hideOverlay) {
        ctx.imageSmoothingEnabled = false;
        ctx.drawImage(D.overlay, 0, 0);
        ctx.fillStyle = "rgba(255,40,40,0.22)";
        const lp = Math.floor(D.W * LEFT_PCT / 100);
        const bp = Math.floor(D.H * BOTTOM_PCT / 100);
        ctx.fillRect(0, 0, lp, D.H);
        ctx.fillRect(0, D.H - bp, D.W, bp);
        const h = S.hover;
        if (h && (h.type === "remove" || h.type === "restore")) {
          ctx.drawImage(hoverOutline(h.id), D.minx[h.id], D.miny[h.id]);
        }
      }
      ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
      if (S.hideOverlay) return;
      // removed cells: a red X sized to the cell, so "removed" never looks
      // like a counted cell that happens to be drawn in a warm colour
      ctx.lineCap = "round";
      for (let id = 1; id < D.status.length; id++) {
        if (D.status[id] !== REMOVED) continue;
        const [px, py] = toScreen(D.cx[id], D.cy[id]);
        const r = Math.max(5, Math.min(14, 0.35 * S.view.s *
                  Math.max(D.maxx[id] - D.minx[id], D.maxy[id] - D.miny[id])));
        ctx.beginPath();
        ctx.moveTo(px - r, py - r); ctx.lineTo(px + r, py + r);
        ctx.moveTo(px + r, py - r); ctx.lineTo(px - r, py + r);
        ctx.strokeStyle = "#000"; ctx.lineWidth = 5; ctx.stroke();
        ctx.strokeStyle = "#ff2b2b"; ctx.lineWidth = 3; ctx.stroke();
      }
      ctx.lineCap = "butt";
      ctx.lineWidth = 2;
      for (const d of D.dots) {
        const [px, py] = toScreen(d.x, d.y);
        const hot = S.hover && S.hover.type === "deldot" && S.hover.dot === d;
        ctx.beginPath();
        ctx.arc(px, py, DOT_R, 0, 2 * Math.PI);
        ctx.fillStyle = hot ? "#ff3b3b" : "#ffe600";
        ctx.fill();
        ctx.strokeStyle = "#000";
        ctx.stroke();
      }
      const h = S.hover;
      if (h && h.type === "add" && !S.down) {
        const [px, py] = toScreen(h.dot.x, h.dot.y);
        ctx.globalAlpha = 0.55;
        ctx.beginPath();
        ctx.arc(px, py, DOT_R, 0, 2 * Math.PI);
        ctx.fillStyle = "#ffe600"; ctx.fill();
        ctx.strokeStyle = "#000"; ctx.stroke();
        ctx.globalAlpha = 1;
      }
    }

    function drawCorners() {
      const pts = S.corners.length === 4 ? orderedCorners() : S.corners;
      const sp = pts.map(([x, y]) => toScreen(x, y));
      ctx.lineWidth = 2;
      ctx.strokeStyle = "#4aaaff";
      if (sp.length >= 2) {
        ctx.beginPath();
        ctx.moveTo(sp[0][0], sp[0][1]);
        for (const p of sp.slice(1)) ctx.lineTo(p[0], p[1]);
        if (sp.length === 4) {
          ctx.closePath();
          ctx.fillStyle = "rgba(74,170,255,0.12)";
          ctx.fill();
        }
        ctx.stroke();
      }
      S.corners.forEach(([x, y]) => {
        const [px, py] = toScreen(x, y);
        ctx.beginPath();
        ctx.arc(px, py, 9, 0, 2 * Math.PI);
        ctx.fillStyle = "#4aaaff"; ctx.fill();
        ctx.strokeStyle = "#fff"; ctx.stroke();
        ctx.beginPath();
        ctx.moveTo(px - 4, py); ctx.lineTo(px + 4, py);
        ctx.moveTo(px, py - 4); ctx.lineTo(px, py + 4);
        ctx.stroke();
      });
    }

    updateUI();
    return { S, load, getCorners, markStart, onKey, onKeyUp, frame, root,
             active: () => S.pointerIn || root.contains(document.activeElement) };
  }

  // ================================================================ shared
  function loadImage(src) {
    return new Promise((res, rej) => {
      const im = new Image();
      im.onload = () => res(im); im.onerror = rej; im.src = src;
    });
  }

  async function decodeLabels(src, W, H) {
    // No colour conversion: the bytes ARE the ids, so any colour management
    // would corrupt them.
    let bmp;
    try {
      const blob = await (await fetch(src)).blob();
      bmp = await createImageBitmap(blob, {
        colorSpaceConversion: "none", premultiplyAlpha: "none" });
    } catch (e) {
      bmp = await loadImage(src);
    }
    const c = document.createElement("canvas");
    c.width = W; c.height = H;
    const x = c.getContext("2d", { willReadFrequently: true });
    x.drawImage(bmp, 0, 0);
    return x.getImageData(0, 0, W, H).data;
  }

  function makeColors(n) {
    // Golden-angle hues: ids numbered close together, which Cellpose tends to
    // give to neighbours, land far apart on the colour wheel.
    const c = new Uint8Array(n * 3);
    for (let id = 1; id < n; id++) {
      // hues 25..335 deg only: red is reserved for removed cells
      const h = (25 + (id * 137.508) % 310) / 60, x = 1 - Math.abs(h % 2 - 1);
      const k = Math.floor(h);
      const rgb = [[1, x, 0], [x, 1, 0], [0, 1, x], [0, x, 1], [x, 0, 1],
                   [1, 0, x]][k % 6];
      c[id * 3] = rgb[0] * 255; c[id * 3 + 1] = rgb[1] * 255;
      c[id * 3 + 2] = rgb[2] * 255;
    }
    return c;
  }

  function scan() {
    document.querySelectorAll(".gt-root").forEach((root) => {
      const k = root.dataset.key;
      if (INST[k] && INST[k].root === root) return;
      INST[k] = create(root);
      if (PENDING[k]) { const p = PENDING[k]; delete PENDING[k]; INST[k].load(p); }
    });
  }

  function frame() {
    requestAnimationFrame(frame);
    for (const k in INST) INST[k].frame();
  }

  function onKey(e, up) {
    for (const k in INST) {
      const I = INST[k];
      if (!I.active()) continue;
      const tag = (e.target && e.target.tagName) || "";
      // With the mouse over the canvas, shortcuts win even if focus was left
      // in an input; otherwise inputs keep their own keys.
      if (!I.S.pointerIn && (tag === "INPUT" || tag === "TEXTAREA")) return;
      if (I.S.pointerIn && tag === "INPUT" && !up) e.target.blur();
      up ? I.onKeyUp(e) : I.onKey(e);
      return;
    }
  }

  window.addEventListener("keydown", (e) => onKey(e, false), true);
  window.addEventListener("keyup", (e) => onKey(e, true), true);

  window.GT = {
    load(payload) {
      if (!payload) return;
      let p;
      try { p = typeof payload === "string" ? JSON.parse(payload) : payload; }
      catch (e) { return; }
      if (!p || !p.key) return;
      scan();
      if (!INST[p.key]) { PENDING[p.key] = p; return; }
      return INST[p.key].load(p);
    },
    getCorners(key) { scan(); return INST[key] ? INST[key].getCorners() : ""; },
    markStart(key) { scan(); return INST[key] ? INST[key].markStart() : true; },
    _inst: INST,
  };
  setInterval(scan, 300);
  requestAnimationFrame(frame);
})();