/**
 * Differential test: drives the baseline (main) and rewritten scenes with the
 * same random operation sequences and requires identical observable state
 * after every step.
 */
import { afterAll, describe, expect, it } from "vitest";
import * as next from "../src";
import * as base from "./.baseline";
import {
  component,
  flush,
  installFrames,
  rng,
  settle,
  snapshot,
} from "./harness";

type Impl = typeof next;
const impls = [base as unknown as Impl, next] as const;

const css = (style: Record<string, string>) => style as never;

const choreographies = [
  next.defineOriginChoreography({
    name: "layered",
    effects: ({ progress }) => ({
      source: { transform: `translateX(${-progress * 100}px)` },
      target: { transform: `translateX(${(1 - progress) * 100}px)` },
    }),
  }),
  next.defineOriginChoreography({
    name: "probe",
    commitThreshold: 0.5,
    effects: (c) => ({
      frame: { style: css({ filter: `blur(${c.progress}px)` }), layer: 1 },
      source: {
        opacity: 1 - c.progress,
        style: css({
          opacity: "0.9",
          transform: `rotate(${c.velocity}deg)`,
          "--state": `${c.phase}/${c.intent}`,
        }),
      },
      target: {
        transform: c.progress > 0.5 ? "none" : `scale(${c.progress})`,
        layer: 2,
        style: css({
          borderRadius: `${c.viewport.width}x${c.viewport.height}`,
          "--rects": JSON.stringify([
            c.originRect ?? null,
            c.targetRect ?? null,
          ]),
          position: "fixed",
        }),
      },
    }),
  }),
  next.defineOriginChoreography({
    name: "drawer-open",
    persistAtRest: true,
    effects: ({ progress }) => ({
      source: { transform: `translateX(${progress * 66.6667}%)` },
      target: { transform: `translateX(${(progress - 1) * 66.6667}%)` },
    }),
  }),
  next.defineOriginChoreography({
    name: "drawer-close",
    commitThreshold: 0.2,
    effects: ({ progress }) => ({
      source: { transform: `translateX(${-progress * 66.6667}%)` },
      target: { transform: `translateX(${(1 - progress) * 66.6667}%)` },
    }),
  }),
  next.slideLeft,
  next.slideRight,
  next.fade,
];

const views = ["A", "B", "C", "D", "E"].map((name) =>
  next.originView(component(name), undefined, { key: name.toLowerCase() }),
);

function randomAction(r: ReturnType<typeof rng>): next.OriginAction {
  const choreography = r.pick(choreographies);
  const target = r.pick(views);
  const placement = r.pick(["above", "under", undefined] as const);
  switch (r.int(6)) {
    case 0:
      return next.forward(target, choreography, { placement });
    case 1:
      return next.replace(target, choreography, { placement });
    case 2:
    case 3:
      return next.back(choreography, { placement });
    case 4:
      return next.above(target, choreography, {
        history: r.pick(["push", "replace", "back", undefined] as const),
      });
    default:
      return next.under(target, choreography, {
        history: r.pick(["push", "back"] as const),
      });
  }
}

type Pair<T> = [T, T];
export const stats = {
  undecidedFinishes: 0,
  boundary: 0,
  begins: 0,
  beginOk: 0,
};
interface Slot {
  done: [boolean, boolean];
  value: [unknown, unknown];
}

async function runSequence(seed: number, steps: number) {
  const r = rng(seed);
  const frames = installFrames();
  const scenes = impls.map((impl) =>
    impl.createOriginScene({
      initial: seed % 3 === 0 ? [views[0]!, views[1]!] : views[0]!,
    }),
  ) as Pair<next.OriginScene>;
  const handles: Pair<next.OriginOperationHandle>[] = [];
  const slots: Slot[] = [];
  const log: string[] = [];

  const track = (promises: Pair<Promise<unknown>>) => {
    const slot: Slot = { done: [false, false], value: [undefined, undefined] };
    promises.forEach(
      (promise, index) =>
        void settle(promise).then((value) => {
          slot.done[index] = true;
          slot.value[index] = value;
        }),
    );
    slots.push(slot);
    return slot;
  };

  const check = (label: string) => {
    expect(snapshot(scenes[1]), `${label}\n${log.join("\n")}`).toEqual(
      snapshot(scenes[0]),
    );
    for (const slot of slots) {
      expect(slot.done[1], label).toBe(slot.done[0]);
      expect(slot.value[1], label).toEqual(slot.value[0]);
    }
  };

  const pickHandle = () => {
    const liveIds = new Set(scenes[0].operations.value.map((o) => o.id));
    const live = handles.filter(([handle]) => liveIds.has(handle.id));
    return live.length && r.chance(0.85) ? r.pick(live) : r.pick(handles);
  };
  const boundaryUpdate = (pair: Pair<next.OriginOperationHandle>) => {
    // Bias toward the commit-decision boundaries.
    const progress = r.chance(0.4)
      ? r.pick([0, 0.2, 0.35999, 0.36, 0.49999, 0.5, 1])
      : r.next() * 1.4 - 0.2;
    const velocity = r.chance(0.2)
      ? undefined
      : r.chance(0.4)
        ? r.pick([-0.3, 0, 0.29999, 0.3, 0.30001, 0.31])
        : r.next() * 4 - 2;
    log.push(`update ${pair[0].id} ${progress} ${velocity}`);
    pair.forEach((handle) => handle.update(progress, velocity));
  };

  for (let step = 0; step < steps; step += 1) {
    const roll = r.next();
    const nodeKeys = scenes[0].nodes.value.map((node) => node.key);
    if (roll < 0.3 || handles.length === 0) {
      const originKey = r.chance(0.03) ? "missing::0" : r.pick(nodeKeys);
      const action = randomAction(r);
      log.push(
        `begin ${originKey} ${action.history} ${action.choreography.name}`,
      );
      const slot = track(
        scenes.map((scene) => scene.begin(originKey, action)) as Pair<
          Promise<next.OriginOperationHandle>
        >,
      );
      await flush();
      if (slot.done[0] && slot.done[1]) {
        const [a, b] = slot.value as Pair<
          { ok: true; value: next.OriginOperationHandle } | { ok: false }
        >;
        stats.begins += 1;
        if (a.ok && b.ok) {
          stats.beginOk += 1;
          handles.push([a.value, b.value]);
          // Handles are compared by identity fields only.
          slot.value = [
            { id: a.value.id, o: a.value.originKey, t: a.value.targetKey },
            { id: b.value.id, o: b.value.originKey, t: b.value.targetKey },
          ];
        }
      }
    } else if (roll < 0.55) {
      boundaryUpdate(pickHandle());
    } else if (roll < 0.75) {
      const pair = pickHandle();
      if (r.chance(0.5)) boundaryUpdate(pair);
      const options = {
        commit: r.pick([true, false, undefined]),
        animate: r.chance(0.5),
      };
      log.push(`finish ${pair[0].id} ${JSON.stringify(options)}`);
      const live = scenes[0].operations.value.find((o) => o.id === pair[0].id);
      if (live && options.commit === undefined) {
        stats.undecidedFinishes += 1;
        if (live.velocity >= 0.3 && live.velocity < 0.31) stats.boundary += 1;
      }
      track(
        pair.map((handle) => handle.finish(options)) as Pair<Promise<boolean>>,
      );
    } else if (roll < 0.82) {
      const pair = pickHandle();
      const animate = r.pick([true, false, undefined]);
      log.push(`cancel ${pair[0].id} ${animate}`);
      track(
        pair.map((handle) => handle.cancel({ animate })) as Pair<Promise<void>>,
      );
    } else {
      const count = 1 + r.int(12);
      log.push(`frames ${count}`);
      for (let i = 0; i < count; i += 1) frames.advance(4 + r.int(40));
    }
    if (!r.chance(0.15)) await flush();
    check(`seed ${seed} step ${step}`);
  }

  // Drain every running spring and compare the resting state.
  for (let i = 0; i < 400 && frames.pending(); i += 1) frames.advance(16);
  await flush();
  check(`seed ${seed} drained`);
}

describe("scene: baseline vs rewrite", () => {
  it("produces identical action and intent objects", () => {
    const target = views[1]!;
    const c = choreographies[0]!;
    const calls: Array<(m: Impl) => unknown> = [
      (m) => m.originAction(target, c),
      (m) => m.originAction(target, c, { placement: "under", history: "back" }),
      (m) => m.forward(target),
      (m) => m.forward(target, { placement: "under" }),
      (m) => m.forward(target, c),
      (m) => m.forward(target, c, { placement: "under" }),
      (m) => m.replace(target),
      (m) => m.replace(target, c, {}),
      (m) => m.back(),
      (m) => m.back({ placement: "above" }),
      (m) => m.back(c),
      (m) => m.back(c, { placement: "above" }),
      (m) => m.above(target),
      (m) => m.above(target, { history: "replace" }),
      (m) => m.above(target, c),
      (m) => m.above(target, c, { history: "back" }),
      (m) => m.under(target),
      (m) => m.under(target, c, { history: "back" }),
      (m) => m.normalizedEffect(undefined),
      (m) => m.normalizedEffect({ transform: "x", layer: 2 }, -1),
    ];
    for (const call of calls) {
      const [a, b] = impls.map(call);
      expect(b).toStrictEqual(a);
      expect(Object.keys(b as object)).toEqual(Object.keys(a as object));
    }
  });

  afterAll(() => console.log("STATS", JSON.stringify(stats)));

  it("exports the same runtime names", () => {
    expect(Object.keys(next).sort()).toEqual(Object.keys(base).sort());
  });

  const seeds = Number(process.env.SEEDS ?? 300);
  for (let seed = 1; seed <= seeds; seed += 1) {
    it(`random sequence ${seed}`, () => runSequence(seed, 60));
  }
});