/**
 * A drag writes the model on every pointer move but tells the editor once per frame (#213): the
 * model event rebuilds panels and pictures, and a mouse reports faster than the screen draws.
 */
import type { Application } from 'pixi.js';
import { beforeEach, describe, expect, it, vi } from 'vitest';
import type { GraphAsset } from '../../src/core/model/Asset';
import { FramePreview } from '../../src/editor/framePreview';
import { GraphDrags } from '../../src/editor/graph/graphDrags';
import type { GraphCanvasHost } from '../../src/editor/graph/graphHost';
import type { EditorState } from '../../src/editor/state';
import { initRenderLoop, resetRenderLoop } from '../../src/ui/render';

/** One frame of the render loop, the way the ticker runs it. */
function frames(): () => void {
  const added: Array<() => void> = [];
  const app = {
    render(): void {},
    ticker: {
      add: (fn: () => void) => added.push(fn),
      remove: () => undefined,
    },
  };
  initRenderLoop(app as unknown as Application);
  return () => added.forEach((fn) => fn());
}

function fakeState() {
  return {
    selectedAnnotationIds: [] as string[],
    selectedNodeIds: ['n1'],
    preview: vi.fn(),
    execute: vi.fn(() => true),
  };
}

describe('FramePreview', () => {
  beforeEach(() => resetRenderLoop());

  it('turns any number of requests in one frame into a single preview', () => {
    const tick = frames();
    const state = fakeState();
    const preview = new FramePreview(state, 'drag');
    for (let i = 0; i < 5; i++) preview.request();
    expect(state.preview).not.toHaveBeenCalled();
    tick();
    expect(state.preview).toHaveBeenCalledTimes(1);
    tick();
    expect(state.preview).toHaveBeenCalledTimes(1);
  });

  it('drops the waiting preview on cancel', () => {
    const tick = frames();
    const state = fakeState();
    const preview = new FramePreview(state, 'drag');
    preview.request();
    preview.cancel();
    tick();
    expect(state.preview).not.toHaveBeenCalled();
  });

  it('keeps two gestures of the same name apart', () => {
    const tick = frames();
    const a = fakeState();
    const b = fakeState();
    new FramePreview(a, 'drag').request();
    new FramePreview(b, 'drag').request();
    tick();
    expect(a.preview).toHaveBeenCalledTimes(1);
    expect(b.preview).toHaveBeenCalledTimes(1);
  });
});

describe('dragging a node in the graph', () => {
  beforeEach(() => resetRenderLoop());

  function rig() {
    const state = fakeState();
    const asset = {
      id: 'b',
      graph: { nodes: [{ id: 'n1', type: 'Add', x: 0, y: 0, params: {} }], edges: [] },
    } as unknown as GraphAsset;
    const host = {
      state: state as unknown as EditorState,
      assetId: () => 'b',
      asset: () => asset,
      nodeBoxes: () => [{ id: 'n1', x: 0, y: 0, w: 100, h: 40 }],
      toGraph: (p: { x: number; y: number }) => ({ x: p.x, y: p.y }),
      zoom: () => 1,
      snapping: () => false,
    } as unknown as GraphCanvasHost;
    return { state, node: asset.graph.nodes[0]!, drags: new GraphDrags(host) };
  }

  it('moves the node with every pointer move and previews once a frame', () => {
    const tick = frames();
    const { state, node, drags } = rig();
    drags.grabNodes({ x: 10, y: 10 });
    for (let i = 1; i <= 5; i++) {
      drags.move({ x: 10 + i * 10, y: 10 });
      expect(node.x).toBe(i * 10);
    }
    expect(state.preview).not.toHaveBeenCalled();
    tick();
    expect(state.preview).toHaveBeenCalledTimes(1);
  });

  it('leaves nothing for the frame after the release: the command has the last word', () => {
    const tick = frames();
    const { state, node, drags } = rig();
    drags.grabNodes({ x: 10, y: 10 });
    drags.move({ x: 50, y: 30 });
    drags.releaseNodes();
    expect(state.execute).toHaveBeenCalledTimes(1);
    expect(node.x).toBe(0);
    tick();
    expect(state.preview).not.toHaveBeenCalled();
  });
});