/** The zoom transition (#309): the way between two views, the driver that shows it, and its setting. */
import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
import {
  generalSettings,
  keepGeneralSettings,
  resetGeneralSettings,
  zoomTransitionMs,
} from '../../src/editor/generalSettings';
import { zoomedAbout } from '../../src/editor/graph/graphView';
import { localToImage, zoomAbout } from '../../src/editor/texture/sheetView';
import { easeOut, tweenView, type ViewMap, ViewTween } from '../../src/editor/viewTween';

function fakeClock() {
  let time = 0;
  const ticks = new Set<() => void>();
  return {
    now: () => time,
    add: (fn: () => void) => void ticks.add(fn),
    remove: (fn: () => void) => void ticks.delete(fn),
    advance(ms: number) {
      time += ms;
      for (const fn of [...ticks]) fn();
    },
    get attached() {
      return ticks.size;
    },
  };
}

/** A surface with a view and nothing else; `draws` counts what it was asked to draw. */
function surface(start: ViewMap = { scale: 1, x: 0, y: 0 }) {
  const s = { view: { ...start }, draws: 0 };
  const target = {
    read: () => ({ ...s.view }),
    write: (map: ViewMap) => void (s.view = { ...map }),
    draw: () => void (s.draws += 1),
  };
  return { s, target };
}

/** The world point shown at a screen point. */
const worldAt = (view: ViewMap, x: number, y: number) => ({
  x: (x - view.x) / view.scale,
  y: (y - view.y) / view.scale,
});

describe('the way between two views', () => {
  it('starts on the first and ends on the second', () => {
    const from = { scale: 1, x: 10, y: 20 };
    const to = { scale: 3, x: -40, y: 5 };
    expect(tweenView(from, to, 0)).toEqual(from);
    expect(tweenView(from, to, 1)).toEqual(to);
  });

  it('keeps the graph point under the pointer under it all the way', () => {
    const from = { pan: { x: 120, y: 80 }, zoom: 1 };
    const to = zoomedAbout(from, { x: 300, y: 200 }, 2);
    const a = { scale: from.zoom, x: from.pan.x, y: from.pan.y };
    const b = { scale: to.zoom, x: to.pan.x, y: to.pan.y };
    for (const t of [0.1, 0.5, 0.9]) {
      const mid = worldAt(tweenView(a, b, t), 300, 200);
      expect(mid.x).toBeCloseTo(180, 9);
      expect(mid.y).toBeCloseTo(120, 9);
    }
  });

  it('keeps the picture pixel under the pointer under it in the sheet tabs', () => {
    const from = { panX: 40, panY: -12, zoom: 4 };
    const to = zoomAbout(from, 0.5, 250, 90);
    const mid = tweenView(
      { scale: from.zoom, x: from.panX, y: from.panY },
      { scale: to.zoom, x: to.panX, y: to.panY },
      0.4,
    );
    const pixel = localToImage({ panX: mid.x, panY: mid.y, zoom: mid.scale }, 250, 90);
    const before = localToImage(from, 250, 90);
    expect(pixel.x).toBeCloseTo(before.x, 9);
    expect(pixel.y).toBeCloseTo(before.y, 9);
  });

  it('moves the scale by equal ratios, so halfway from 1 to 4 is 2', () => {
    expect(tweenView({ scale: 1, x: 0, y: 0 }, { scale: 4, x: 0, y: 0 }, 0.5).scale).toBeCloseTo(2, 12);
  });

  it('slides between two views of the same scale', () => {
    expect(tweenView({ scale: 2, x: 0, y: 10 }, { scale: 2, x: 100, y: 30 }, 0.25)).toEqual({
      scale: 2,
      x: 25,
      y: 15,
    });
  });

  it('eases out: most of the way early, nothing past the end', () => {
    expect(easeOut(0)).toBe(0);
    expect(easeOut(1)).toBe(1);
    expect(easeOut(2)).toBe(1);
    expect(easeOut(0.5)).toBeCloseTo(0.875, 12);
  });
});

describe('the transition of a view', () => {
  const double = (s: { view: ViewMap }) => () => {
    s.view = { scale: s.view.scale * 2, x: s.view.x * 2, y: s.view.y * 2 };
  };

  it('shows the way from what was on screen to the new view, and lets go at the end', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 200, clock);
    tween.change(double(s));
    expect(s.view).toEqual({ scale: 1, x: 0, y: 0 });
    expect(tween.moving).toBe(true);
    expect(tween.heading).toEqual({ scale: 2, x: 0, y: 0 });
    clock.advance(100);
    expect(s.view.scale).toBeGreaterThan(1);
    expect(s.view.scale).toBeLessThan(2);
    clock.advance(100);
    expect(s.view).toEqual({ scale: 2, x: 0, y: 0 });
    expect(tween.moving).toBe(false);
    expect(clock.attached).toBe(0);
  });

  it('adds quick steps up to exactly as many steps, starting the way from what is shown', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 200, clock);
    tween.change(double(s));
    clock.advance(50);
    const shown = { ...s.view };
    tween.change(double(s));
    expect(tween.heading?.scale).toBe(4);
    expect(s.view).toEqual(shown);
    clock.advance(200);
    expect(s.view.scale).toBe(4);
  });

  it('keeps its pace when a wheel event makes no step', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 200, clock);
    tween.change(double(s));
    clock.advance(50);
    tween.change(() => {});
    clock.advance(150);
    expect(tween.moving).toBe(false);
    expect(s.view.scale).toBe(2);
  });

  it('lets go when something else moves the view', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 200, clock);
    tween.change(double(s));
    clock.advance(50);
    s.view = { scale: 7, x: 1, y: 2 };
    clock.advance(16);
    expect(s.view).toEqual({ scale: 7, x: 1, y: 2 });
    expect(tween.moving).toBe(false);
    expect(clock.attached).toBe(0);
  });

  it('jumps at once at 0 ms', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 0, clock);
    tween.change(double(s));
    expect(s.view.scale).toBe(2);
    expect(tween.moving).toBe(false);
    expect(clock.attached).toBe(0);
  });

  it('lands on the target without drawing, and finishes by drawing it', () => {
    const clock = fakeClock();
    const { s, target } = surface();
    const tween = new ViewTween(target, () => 200, clock);
    tween.change(double(s));
    clock.advance(50);
    const draws = s.draws;
    tween.land();
    expect(s.view.scale).toBe(2);
    expect(s.draws).toBe(draws);
    tween.change(double(s));
    tween.finish();
    expect(s.view.scale).toBe(4);
    expect(s.draws).toBe(draws + 1);
    expect(clock.attached).toBe(0);
  });
});

describe('the general settings', () => {
  function memoryStore() {
    const items = new Map<string, string>();
    return {
      items,
      getItem: (key: string) => items.get(key) ?? null,
      setItem: (key: string, value: string) => void items.set(key, value),
    };
  }
  beforeEach(() => resetGeneralSettings());
  afterEach(() => {
    vi.unstubAllGlobals();
    resetGeneralSettings();
  });

  it('starts at 200 ms where nothing was kept', () => {
    vi.stubGlobal('window', { localStorage: memoryStore() });
    expect(generalSettings().zoomTransitionMs).toBe(200);
  });

  it('keeps the transition in the browser and reads it back on a new page', () => {
    const store = memoryStore();
    vi.stubGlobal('window', { localStorage: store });
    keepGeneralSettings({ zoomTransitionMs: 350 });
    resetGeneralSettings();
    expect(generalSettings().zoomTransitionMs).toBe(350);
    expect(JSON.parse(store.items.get('game-maker.general-settings') ?? '')).toEqual({
      zoomTransitionMs: 350,
    });
  });

  it('holds the transition to whole ms from 0 to 1000', () => {
    expect([zoomTransitionMs(5000), zoomTransitionMs(-3), zoomTransitionMs(12.6)]).toEqual([1000, 0, 13]);
    expect(zoomTransitionMs('fast')).toBe(200);
  });
});