import { type Application, Color, type ColorSource, type Container, Mesh, Rectangle, Text } from 'pixi.js';
import { NameTransitionCommand } from '../core/commands/graphCommands';
import { resolveObjects } from '../core/model/instance';
import { findObjectHolder } from '../core/model/Project';
import type { FrameRect } from '../core/model/texture';
import { effectiveScale, gameClock } from '../core/time';
import {
  activeDrag,
  afterFrames,
  Button,
  currentMenu,
  isRendering,
  renderCount,
  requestRender,
  ui,
  Widget,
} from '../ui';
import { particleLibrary } from '../viewport/ParticleLibrary';
import { shaderLibrary } from '../viewport/ShaderLibrary';
import { soundLibrary } from '../viewport/SoundLibrary';
import { textureLibrary } from '../viewport/TextureLibrary';
import type { CentreTab, Editor } from './Editor';
import { currentFontPicker } from './font/FontPicker';
import { currentNodePalette } from './graph/NodePalette';
import { currentSoundPicker } from './sound/SoundPicker';
import { currentImagePicker } from './texture/ImagePicker';
import type { EditorState } from './state';

/**
 * Installs `window.__gm`, which the check scripts in tools/ use to find widgets by their
 * visible text and to read editor state.
 */
export function installDebugHook(app: Application, state: EditorState, editor: Editor): void {
  const { viewport, gameView, graphEditor, textureEditor, containerEditor, hierarchy, assets, inspector } =
    editor;
  const centreOf = (widget: { getGlobalPosition(): { x: number; y: number }; w: number; h: number }) => {
    const p = widget.getGlobalPosition();
    return { x: p.x + widget.w / 2, y: p.y + widget.h / 2 };
  };
  /** The overlap of two global rectangles; an empty one when they do not meet. */
  const intersect = (a: Rectangle, b: Rectangle): Rectangle => {
    const x = Math.max(a.x, b.x);
    const y = Math.max(a.y, b.y);
    return new Rectangle(
      x,
      y,
      Math.max(0, Math.min(a.right, b.right) - x),
      Math.max(0, Math.min(a.bottom, b.bottom) - y),
    );
  };
  const rectOf = (widget: { getGlobalPosition(): { x: number; y: number }; w: number; h: number }) => {
    const p = widget.getGlobalPosition();
    return { x: p.x, y: p.y, w: widget.w, h: widget.h };
  };
  /**
   * Every text under `root` that is really on screen, in drawing order (the topmost last), handed
   * to `visit` with the centre a click on it would use.
   *
   * A row scrolled out of its list is still `visible` – only masked away – and reporting it would
   * hand a check a point outside the panel, where the click lands on whatever is underneath. That
   * is how a step that passes on a short list fails on a long one (#39 in CI), so a text whose
   * centre falls outside the clipping it sits in counts as not being there at all.
   *
   * Every hook that reads text goes through here. A `locate` that refuses a scrolled-away row
   * while `overlayTexts` still lists it is worse than either rule alone: a check picks a row off
   * the one hook and then cannot find it with the other.
   *
   * The clip is the box of the *widget* that owns the mask, not the mask itself: Pixi hands a
   * graphics that serves as a mask to the mask effect, and `getBounds()` on it then reports an
   * empty rectangle at the origin – which would throw away every masked text in the editor.
   */
  const eachText = (root: Container, visit: (node: Text, point: { x: number; y: number }) => void): void => {
    const walk = (node: Container, clip: Rectangle | null, owner: Widget | null): void => {
      if (!node.visible) return;
      const holder = node instanceof Widget ? node : owner;
      let inner = clip;
      if (node.mask && holder) {
        const r = rectOf(holder);
        const box = new Rectangle(r.x, r.y, r.w, r.h);
        inner = clip ? intersect(clip, box) : box;
      }
      if (node instanceof Text) {
        // Global bounds, not `width`/`height`: those are unscaled, and inside the graph canvas
        // (which is scaled by the zoom) that put the point right of the text it was meant to hit.
        const box = node.getBounds();
        const point = { x: box.x + box.width / 2, y: box.y + box.height / 2 };
        if (!inner || inner.contains(point.x, point.y)) visit(node, point);
        return;
      }
      for (const child of node.children) walk(child, inner, holder);
    };
    walk(root, null, null);
  };
  /** Centres of every visible text equal to `text`, in drawing order (the topmost last). */
  const locateAll = (text: string): { x: number; y: number }[] => {
    const hits: { x: number; y: number }[] = [];
    eachText(app.stage, (node, point) => {
      if (node.text === text) hits.push(point);
    });
    return hits;
  };
  const locate = (text: string, last = false): { x: number; y: number } | null => {
    const hits = locateAll(text);
    return (last ? hits.at(-1) : hits[0]) ?? null;
  };
  /** Fill colour of a visible text, as `#rrggbb` – what tells an override label from a plain one. */
  const textColor = (text: string): string | null => {
    let found: string | null = null;
    const walk = (node: Container): void => {
      if (found !== null || !node.visible) return;
      if (node instanceof Text && node.text === text) {
        found = new Color(node.style.fill as ColorSource).toHex();
        return;
      }
      for (const child of node.children) walk(child);
    };
    walk(app.stage);
    return found;
  };
  /**
   * Centre of the control of an inspector row, addressed by its label. A row aligns its label to a
   * *minimum* width, so a label wider than the column pushes its control right – which is why a
   * fixed offset from the label's own text is the wrong way to click one.
   */
  const fieldOf = (label: string, last = false): { x: number; y: number; left: number } | null => {
    let found: Text | null = null;
    const walk = (node: Container): void => {
      if ((found !== null && !last) || !node.visible) return;
      if (node instanceof Text && node.text === label) {
        found = node;
        return;
      }
      for (const child of node.children) walk(child);
    };
    walk(app.stage);
    // TypeScript does not track the assignment inside `walk`, hence the cast.
    let owner: Container | null = (found as Text | null)?.parent ?? null;
    while (owner && !(owner instanceof Widget)) owner = owner.parent;
    const row = owner?.parent;
    if (!row || !owner) return null;
    const control = row.children[row.children.indexOf(owner) + 1];
    if (!(control instanceof Widget)) return null;
    return { ...centreOf(control), left: control.getGlobalPosition().x };
  };
  /**
   * The visible text of the overlay layer, in drawing order – everything an open popup shows.
   * Menus hide filtered-out entries, so this is also what a search box currently leaves, and a
   * list taller than its popup only reports the rows currently scrolled into it.
   */
  const overlayTexts = (): string[] => {
    const out: string[] = [];
    eachText(ui().overlay, (node) => {
      if (node.text) out.push(node.text);
    });
    return out;
  };
  /**
   * Visible texts drawn wider than the widget that owns them. The owner's box is its declared
   * `w`/`h`, not `getBounds()`: a Pixi container's bounds are the union of its children –
   * including the overflowing text – so every overflow would measure as zero.
   */
  const textOverflows = (all = false): { text: string; owner: string; over: number }[] => {
    const out: { text: string; owner: string; over: number }[] = [];
    const walk = (node: Container, owner: Widget | null, clipped: boolean): void => {
      if (!node.visible) return;
      const isWidget = node instanceof Widget;
      const box = isWidget ? node : owner;
      // A mask further up does not excuse a label spilling out of its own control, so the
      // question restarts at every widget. `Boolean`, not `!== null`: Pixi's mask getter
      // returns `undefined` when nothing masks.
      const masked = (isWidget ? false : clipped) || Boolean(node.mask);
      if (node instanceof Text) {
        if (!box || !node.text || (masked && !all)) return;
        const text = node.getBounds();
        const origin = box.getGlobalPosition();
        const over = Math.max(text.x + text.width - (origin.x + box.w), origin.x - text.x);
        if (over > 1 || all) {
          out.push({ text: node.text, owner: box.constructor.name, over: Math.round(over) });
        }
        return;
      }
      for (const child of node.children) walk(child, box, masked);
    };
    walk(app.stage, null, false);
    return out;
  };
  /**
   * The counterpart of `textOverflows`: buttons whose label was shortened away to nothing, which
   * leaves a control that says nothing at all. An empty `Text` is invisible to the overflow walk.
   */
  const labelsDropped = (): { text: string; owner: string; w: number }[] => {
    const out: { text: string; owner: string; w: number }[] = [];
    const walk = (node: Container): void => {
      if (!node.visible) return;
      if (node instanceof Button && node.text && !node.shownText) {
        out.push({ text: node.text, owner: node.constructor.name, w: node.w });
      }
      for (const child of node.children) walk(child);
    };
    walk(app.stage);
    return out;
  };
  /** What the last visible button labelled `text` draws – shorter when it was truncated. */
  const shownLabel = (text: string): string | null => {
    let shown: string | null = null;
    const walk = (node: Container): void => {
      if (!node.visible) return;
      if (node instanceof Button && node.text === text) shown = node.shownText;
      for (const child of node.children) walk(child);
    };
    walk(app.stage);
    return shown;
  };
  /** Screen rectangle of the open popup (the backdrop is not a widget), or null when none is. */
  const overlayRect = (): { x: number; y: number; w: number; h: number } | null => {
    const popups = ui().overlay.children.filter((node): node is Widget => node instanceof Widget);
    const popup = popups[popups.length - 1];
    if (!popup) return null;
    const p = popup.getGlobalPosition();
    return { x: p.x, y: p.y, w: popup.w, h: popup.h };
  };
  /**
   * A holder's objects the way the editor sees them: the content of placed containers is resolved
   * from the template, so it is nowhere in `holder.objects` (see `model/instance.ts`).
   */
  const objectsOf = (holderId: string) => {
    const holder = findObjectHolder(state.project, holderId);
    return holder ? resolveObjects(state.project, holder) : [];
  };
  (window as unknown as { __gm: unknown }).__gm = {
    state,
    /** The Pixi application, for probes that need the renderer or the stage. */
    app,
    sceneObjects: () => (state.activeScene ? objectsOf(state.activeScene.id) : []),
    locate,
    locateAll,
    inspectorField: fieldOf,
    inspectorInfo: () => inspector.debugInfo(),
    textColor,
    overlayTexts,
    overlayRect,
    /** Entries of the open menu in drawn order, `null` for a separator line (#43). */
    menuRows: () => currentMenu()?.rowsDrawn() ?? null,
    textOverflows,
    labelsDropped,
    shownLabel,
    tabRow: () => editor.tabRow(),
    /** The dividers left and right of the centre column – dragging them narrows the tab row. */
    panelSplitters: () => ({ left: centreOf(editor.leftSplitter), right: centreOf(editor.rightSplitter) }),
    viewportCenter: () => centreOf(viewport),
    /** Pans the Scene tab to a world point – a step's own lane, away from what earlier steps left. */
    lookAt: (x: number, y: number) => viewport.lookAt(x, y),
    /** Its drawn box – a step that wants an empty spot must stay inside what the console left over. */
    viewportRect: () => {
      const p = viewport.getGlobalPosition();
      return { x: p.x, y: p.y, w: viewport.w, h: viewport.h };
    },
    /**
     * A point in the viewport that no object covers – steps click there to deselect. A fixed
     * offset from the centre lands on an object as soon as the viewport changes size.
     */
    emptySpot: () => {
      const p = viewport.getGlobalPosition();
      const scene = state.activeScene;
      const taken = scene
        ? objectsOf(scene.id)
            .map((object) => viewport.objectRect(object.id))
            .filter((rect): rect is NonNullable<typeof rect> => rect !== null)
        : [];
      const clear = (x: number, y: number) =>
        !taken.some((r) => x >= r.x - 12 && x <= r.x + r.w + 12 && y >= r.y - 12 && y <= r.y + r.h + 12);
      for (let y = p.y + viewport.h - 24; y > p.y + 24; y -= 24) {
        for (let x = p.x + 24; x < p.x + viewport.w - 24; x += 24) if (clear(x, y)) return { x, y };
      }
      return null;
    },
    viewportInfo: () => viewport.debugInfo(),
    /** Where a dragged asset would land in the Scene tab, and why not when it may not. */
    dropPreview: () => viewport.dropInfo(),
    /** The panel-to-view drag in flight, if any – a drop that never started looks like a refused one. */
    dragPayload: () => activeDrag(),
    /** An asset row by id – two assets can share a name with the container picker's label. */
    assetRow: (id: string) => assets.rowGlobal(id),
    assetRowColor: (id: string) => assets.rowColor(id),
    /** The panel's own rectangle – what tells a row in view from one scrolled past its edge. */
    assetsRect: () => rectOf(assets),
    gameInfo: () => gameView.debugInfo(),
    /** Selection outlines in the Scene tab: a switched-off object is invisible but still framed. */
    gizmos: () => viewport.gizmoInfo(),
    layerOf: (id: string) => viewport.layerOf(id),
    /** The icon a particle source wears in the Scene tab, with its name and its owner link. */
    sceneIcon: (id: string) => viewport.iconInfo(id),
    drawOrder: () => viewport.drawOrder(),
    objectScreen: (id: string) => viewport.objectScreen(id),
    objectRect: (id: string) => viewport.objectRect(id),
    /** The same for the Game tab – through the camera, so what the player sees. */
    gameScreen: (id: string) => gameView.objectScreen(id),
    gameRect: (id: string) => gameView.objectRect(id),
    gameCenter: () => centreOf(gameView),
    graph: {
      current: () => graphEditor.currentAssetId,
      portAt: (nodeId: string, port: string, isOutput: boolean) =>
        graphEditor.canvas.portGlobal(nodeId, port, isOutput),
      nodeAt: (nodeId: string) => graphEditor.canvas.nodeGlobal(nodeId),
      chevronAt: (nodeId: string) => graphEditor.canvas.chevronGlobal(nodeId),
      nodeLabel: (nodeId: string) => graphEditor.canvas.nodeLabel(nodeId),
      nodeProblem: (nodeId: string) => graphEditor.canvas.nodeProblem(nodeId),
      nodeSettings: (nodeId: string) => graphEditor.canvas.nodeSettings(nodeId),
      /** Each input row as drawn: its name, and the inline value beside it while unconnected. */
      nodeInputs: (nodeId: string) => graphEditor.canvas.nodeInputs(nodeId),
      /** Each output row as drawn: while playing, the value it last carried in front of its name. */
      nodeOutputs: (nodeId: string) => graphEditor.canvas.nodeOutputs(nodeId),
      /** Beads in flight on exec edges as drawn, in graph coordinates; `progress` 0 = source, 1 = target. */
      beads: () => graphEditor.canvas.beadsDrawn(),
      /** Drawn rectangles on screen: what "fit" has to keep inside `canvasRect`. */
      nodeRect: (nodeId: string) => graphEditor.canvas.nodeRect(nodeId),
      canvasRect: () => graphEditor.canvas.canvasRect(),
      /** Bare canvas below every node – where a step right-clicks to open the palette. */
      emptySpot: () => graphEditor.canvas.emptySpotGlobal(),
      /**
       * What the open palette lists, in order. No colour check can see a ranking: the rows all
       * look alike, only their order carries the answer (#43).
       */
      paletteRows: () => currentNodePalette()?.rowsDrawn() ?? null,
      selected: () => state.selectedNodeIds,
      dropTarget: () => graphEditor.canvas.pendingDropTarget(),
      danglingEdge: () => graphEditor.canvas.danglingEdgeVisible(),
      edgeDrawn: (edgeId: string) => graphEditor.canvas.edgeDrawn(edgeId),
      foldMark: (edgeId: string, isOutput: boolean) => graphEditor.canvas.foldMarkGlobal(edgeId, isOutput),
      foldMarks: () => graphEditor.canvas.foldMarksDrawn(),
      // The canvas, not the whole tab: a centre measured through the header sits above the
      // drawing area.
      center: () => centreOf(graphEditor.canvas),
      pickerWidth: () => graphEditor.picker.w,
      pickerAt: () => centreOf(graphEditor.picker),
      snapping: () => graphEditor.canvas.snapEnabled,
      zoom: () => graphEditor.canvas.zoomLevel,
      crumbs: () => graphEditor.breadcrumb.crumbsDrawn(),
    },
    stateMachine: {
      current: () => editor.stateMachineEditor.currentAssetId,
      pickerAt: () => centreOf(editor.stateMachineEditor.picker),
      nodeAt: (nodeId: string) => editor.stateMachineEditor.canvas.nodeGlobal(nodeId),
      nodeLabel: (nodeId: string) => editor.stateMachineEditor.canvas.nodeLabel(nodeId),
      nodeRect: (nodeId: string) => editor.stateMachineEditor.canvas.nodeRect(nodeId),
      canvasRect: () => editor.stateMachineEditor.canvas.canvasRect(),
      center: () => centreOf(editor.stateMachineEditor.canvas),
      snapping: () => editor.stateMachineEditor.canvas.snapEnabled,
      /** Where a state's hidden pin sits. It is no longer grabbable – `portGrabbable` is the check. */
      portAt: (nodeId: string, port: string, isOutput: boolean) =>
        editor.stateMachineEditor.canvas.portGlobal(nodeId, port, isOutput),
      portGrabbable: (nodeId: string, port: string, isOutput: boolean) =>
        editor.stateMachineEditor.canvas.portGrabbable(nodeId, port, isOutput),
      edgeDrawn: (edgeId: string) => editor.stateMachineEditor.canvas.edgeDrawn(edgeId),
      transitionLabel: (edgeId: string) => editor.stateMachineEditor.canvas.transitionLabelDrawn(edgeId),
      hint: () => editor.stateMachineEditor.canvas.shownHint(),
      /** Names a transition the way the inspector row does, for steps that need one already named. */
      nameTransition: (edgeId: string, name: string) =>
        state.execute(new NameTransitionCommand(editor.stateMachineEditor.currentAssetId, edgeId, name)),
      dropTarget: () => editor.stateMachineEditor.canvas.pendingDropTarget(),
      danglingEdge: () => editor.stateMachineEditor.canvas.danglingEdgeVisible(),
      emptySpot: () => editor.stateMachineEditor.canvas.emptySpotGlobal(),
      selected: () => state.selectedNodeIds,
      /** The start ring and the live marks as drawn – what no colour check could tell apart. */
      startRing: (nodeId: string) => editor.stateMachineEditor.canvas.startRingDrawn(nodeId),
      stateMarks: () => editor.stateMachineEditor.canvas.stateMarksDrawn(),
    },
    particles: {
      current: () => editor.particlesEditor.currentAssetId,
      pickerAt: () => centreOf(editor.particlesEditor.picker),
      info: () => editor.particlesEditor.shownInfo,
      nodeAt: (nodeId: string) => editor.particlesEditor.canvas.nodeGlobal(nodeId),
      nodeLabel: (nodeId: string) => editor.particlesEditor.canvas.nodeLabel(nodeId),
      nodeRect: (nodeId: string) => editor.particlesEditor.canvas.nodeRect(nodeId),
      nodeProblem: (nodeId: string) => editor.particlesEditor.canvas.nodeProblem(nodeId),
      canvasRect: () => editor.particlesEditor.canvas.canvasRect(),
      emptySpot: () => editor.particlesEditor.canvas.emptySpotGlobal(),
      center: () => centreOf(editor.particlesEditor.canvas),
      /** The panel beside the graph: how many particles it draws and which second it stands at. */
      preview: () => ({
        count: editor.particlesEditor.preview.count,
        time: Math.round(editor.particlesEditor.preview.time * 100) / 100,
        holding: editor.particlesEditor.preview.holding,
      }),
      previewRect: () => rectOf(editor.particlesEditor.preview),
      /** Hold button, time readout and slider as they are shown, not as the preview holds them. */
      controls: () => editor.particlesEditor.controls,
      splitterAt: () => centreOf(editor.particlesEditor.splitter),
      sliderAt: () => centreOf(editor.particlesEditor.slider),
      /** Jumps the preview to a second – exact, because a particle is a function of its age. */
      hold: (at: number | null) => editor.particlesEditor.preview.hold(at),
    },
    shader: {
      current: () => editor.shaderEditor.currentAssetId,
      pickerAt: () => centreOf(editor.shaderEditor.picker),
      info: () => editor.shaderEditor.shownInfo,
      nodeAt: (nodeId: string) => editor.shaderEditor.canvas.nodeGlobal(nodeId),
      nodeLabel: (nodeId: string) => editor.shaderEditor.canvas.nodeLabel(nodeId),
      nodeRect: (nodeId: string) => editor.shaderEditor.canvas.nodeRect(nodeId),
      nodeProblem: (nodeId: string) => editor.shaderEditor.canvas.nodeProblem(nodeId),
      nodeSettings: (nodeId: string) => editor.shaderEditor.canvas.nodeSettings(nodeId),
      canvasRect: () => editor.shaderEditor.canvas.canvasRect(),
      emptySpot: () => editor.shaderEditor.canvas.emptySpotGlobal(),
      center: () => centreOf(editor.shaderEditor.canvas),
      snapping: () => editor.shaderEditor.canvas.snapEnabled,
    },
    /** The console panel: its lines as kept, its drawn height, and the divider above it. */
    console: {
      lines: () => editor.console.debugInfo().lines,
      height: () => editor.console.h,
      clear: () => editor.console.clear(),
      scroll: () => editor.console.scrollInfo(),
      centre: () => centreOf(editor.console),
      splitterAt: () => centreOf(editor.consoleSplitter),
    },
    /** The open image picker: what it offers, what is picked, and where a tile sits. */
    imagePicker: () => currentImagePicker()?.debugInfo() ?? null,
    imagePickerTile: (file: string) => currentImagePicker()?.tileGlobal(file) ?? null,
    /** The same for the font picker, whose rows are the preview. */
    fontPicker: () => currentFontPicker()?.debugInfo() ?? null,
    fontPickerRow: (file: string) => currentFontPicker()?.rowGlobal(file) ?? null,
    /** And for the sound picker, whose rows carry a ▶ of their own. */
    soundPicker: () => currentSoundPicker()?.debugInfo() ?? null,
    soundPickerRow: (file: string) => currentSoundPicker()?.rowGlobal(file) ?? null,
    soundPickerPlay: (file: string) => currentSoundPicker()?.playGlobal(file) ?? null,
    /**
     * Voices started, stopped and in flight. CI runs the browser with `--mute-audio`, so nothing
     * is ever heard there: these counters are the only way a check can see that a graph played
     * anything at all, the way `renderStats` is for a repaint that did not happen.
     */
    sound: {
      stats: () => soundLibrary.stats(),
      duration: (file: string) => soundLibrary.duration(file),
      /** Decodes ahead of a check, so a play can be asserted without racing the network. */
      load: (file: string) => soundLibrary.load(file).then((buffer) => buffer?.duration ?? null),
      stopAll: () => soundLibrary.stopAll(),
    },
    /** Which typeface a text ended up drawn in, and how wide it made it. */
    textInfo: (id: string) => viewport.textInfo(id),
    gameTextInfo: (id: string) => gameView.textInfo(id),
    texture: {
      current: () => textureEditor.currentAssetId,
      pickerWidth: () => textureEditor.picker.w,
      /** Where an image pixel of the shown sheet sits on screen (frames are dragged in image coordinates). */
      pointAt: (x: number, y: number) => textureEditor.imageToScreen(x, y),
      rect: () => textureEditor.canvasRect(),
    },
    animation: {
      /** Frames, the one on screen, play state and where the preview picture is drawn. */
      current: () => editor.animationEditor.canvas.debugInfo(),
      tileCentre: (index: number) => editor.animationEditor.canvas.tileCentre(index),
      playButton: () => centreOf(editor.animationEditor.playButton),
      playLabel: () => editor.animationEditor.playButton.text,
    },
    container: {
      current: () => containerEditor.currentAssetId,
      pickerWidth: () => containerEditor.picker.w,
      center: () => centreOf(containerEditor),
      rect: () => containerEditor.canvasRect(),
      /** Where a template object is drawn, so a check can click or sample it. */
      objectScreen: (id: string) => containerEditor.objectScreen(id),
      dropPreview: () => containerEditor.dropInfo(),
    },
    list: {
      info: () => editor.listEditor.debugInfo(),
      /** Where an item's widget sits, so a check can click it – a number field has no findable text. */
      fieldAt: (index: number, field = '') => editor.listEditor.fieldAt(index, field),
      /** The kind mark of a row, or of one field of a struct item – both are pickers. */
      markAt: (index: number, field = '') => editor.listEditor.markAt(index, field),
      nameAt: (index: number, field: string) => editor.listEditor.nameAt(index, field),
    },
    world: () => editor.worldSnapshot(),
    playInfo: () => editor.playInfo(),
    /** The start-scene switch: what it says, and where to click it (its caption is elided). */
    playFrom: () => editor.playFromInfo(),
    playFromAt: () => centreOf(editor.playFromButton),
    /** The scene selector: where it is, and whether it takes a click (it does, play mode or not). */
    sceneSelect: () => ({ ...centreOf(editor.sceneButton), enabled: editor.sceneButton.enabled }),
    /** Behaviors running without Play (`Run in editor`), and how long they have been at it. */
    editorRun: () => editor.editorRunInfo(),
    /** Rows the hierarchy shows – collapsed subtrees are not in here. */
    hierarchyOrder: () => hierarchy.rowOrder(),
    hierarchyChevron: (id: string) => hierarchy.chevronPosition(id),
    /** Centre of a hierarchy row, clear of the chevron – for clicks that must hit the row itself. */
    hierarchyRow: (id: string) => hierarchy.rowPosition(id),
    hierarchyRowColor: (id: string) => hierarchy.rowColor(id),
    hierarchyExpandAll: () => hierarchy.expandAll(),
    hierarchyCollapseAll: () => hierarchy.collapseAll(),
    /** The colour actually on screen at a point, as `#rrggbb` – what was drawn, not what the model says. */
    pixelAt: (x: number, y: number) => {
      const { pixels } = app.renderer.extract.pixels({
        target: app.stage,
        frame: new Rectangle(x, y, 1, 1),
      });
      const hex = (value: number | undefined) => (value ?? 0).toString(16).padStart(2, '0');
      return `#${hex(pixels[0])}${hex(pixels[1])}${hex(pixels[2])}`;
    },
    /** The filter and wrap the GPU sampler actually got, next to the model's – only the driver knows the former. */
    textureFilter: (file: string, rect: FrameRect | null = null) => {
      const texture = textureLibrary.peek(file, rect);
      if (!texture) return null;
      const source = texture.source;
      const renderer = app.renderer as unknown as {
        gl?: WebGL2RenderingContext;
        uid: number;
        texture: { bindSource(source: unknown, location: number): void };
      };
      const gl = renderer.gl;
      const uploaded = Boolean(
        (source as unknown as { _gpuData: Record<number, unknown> })._gpuData[renderer.uid],
      );
      let magFilter = 0;
      let wrapT = 0;
      if (gl) {
        // Through Pixi rather than a raw `bindTexture`, so its idea of what is bound stays true.
        renderer.texture.bindSource(source, 0);
        magFilter = gl.getTexParameter(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER) as number;
        wrapT = gl.getTexParameter(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T) as number;
      }
      return {
        scaleMode: source.scaleMode,
        gpu: magFilter === gl?.NEAREST ? 'nearest' : magFilter === gl?.LINEAR ? 'linear' : 'none',
        wrap:
          wrapT === gl?.CLAMP_TO_EDGE
            ? 'clamp'
            : wrapT === gl?.REPEAT
              ? 'repeat'
              : wrapT === gl?.MIRRORED_REPEAT
                ? 'mirror'
                : 'none',
        uploaded,
      };
    },
    fps: () => editor.fps,
    /**
     * What the render loop did: frames actually drawn, and whether it is currently awake. The
     * only way to see a missing repaint from a check script – `pixelAt` re-renders on demand and
     * would answer correctly even if the screen had been frozen for a minute.
     */
    renderStats: () => ({ drawn: renderCount(), awake: isRendering() }),
    /** Draw again, whatever happens next – what a screenshot needs before it is taken. */
    wake: () => requestRender(),
    /**
     * Resolves once the editor has drawn `count` more frames. The checks await this instead of
     * sleeping a guessed number of milliseconds: a frame is the editor saying it has caught up,
     * where a deadline is only the harness hoping it has.
     */
    afterFrames: (count = 2, timeoutMs = 2000) => afterFrames(count, timeoutMs),
    /** Visible nodes carrying a filter – one extra render pass each; since #77 a shader is none. */
    filterCount: () => {
      let n = 0;
      const walk = (node: Container): void => {
        if (!node.visible) return;
        if (((node.filters as readonly unknown[] | undefined)?.length ?? 0) > 0) n += 1;
        for (const child of node.children) walk(child);
      };
      walk(app.stage);
      return n;
    },
    /** Visible sprite meshes drawing with a shader of their own – one draw call each, no pass (#77). */
    shaderCount: () => {
      let n = 0;
      const walk = (node: Container): void => {
        if (!node.visible) return;
        if (node instanceof Mesh && node.shader) n += 1;
        for (const child of node.children) walk(child);
      };
      walk(app.stage);
      return n;
    },
    /** The global clock: the second it stands at, the scale set, and the one a pause makes of it. */
    globalTime: () => ({
      now: gameClock.now,
      scale: gameClock.scale,
      effective: effectiveScale(gameClock.scale, state.paused),
    }),
    /** Sets the global time scale – there is no slider for it in the GUI yet. */
    setTimeScale: (scale: number) => {
      gameClock.scale = scale;
    },
    /** Holds the shader clock at `at` seconds, so a Time shader's pixels can be measured; null releases it. */
    shaderTime: (at: number | null) => shaderLibrary.freezeTime(at),
    /** The same for particle time, kept apart so one can be held without the other. */
    particleTime: (at: number | null) => particleLibrary.freezeTime(at),
    particleCompiles: () => particleLibrary.compiles,
    /** Every source's clock back to zero on the current (usually frozen) second. */
    particlesRestart: () => {
      viewport.restartParticles(particleLibrary.now());
      gameView.restartParticles(particleLibrary.now());
    },
    /** What a source is drawing in the scene tab, or in the game view while playing. */
    particlesOf: (objectId: string, where: 'scene' | 'game' = 'scene', limit = 8) =>
      (where === 'game' ? gameView : viewport).particleInfo(objectId, limit),
    /** Graphs compiled so far; a moved node must not add one (#65). */
    shaderCompiles: () => shaderLibrary.compiles,
    /** Which views redraw every tick because a Time shader is on screen. */
    animates: () => ({ scene: viewport.animates, game: gameView.animates }),
    lowLatency: () =>
      (app.renderer as unknown as { gl?: WebGL2RenderingContext }).gl?.getContextAttributes()
        ?.desynchronized === true,
    tab: () => editor.tab,
    showTab: (tab: CentreTab) => editor.showTab(tab),
  };
}