drive-between-the-lines/src/sim/save.test.ts

import { describe, expect, it } from 'vitest';
import { generateWorld } from './world';
import { applyWear, freshCondition } from './car';
import { createHeat, stepHeat } from './heat';
import { createIntel, observe, reveal } from './intel';
import { applyMissionImpact, controlAt, createFront, stepFront } from './regions';
import { createQuests } from './quests';
import { apply, isLoadable, serialise, SAVE_VERSION, type Snapshot } from './save';

const world = generateWorld(1337);

/** A campaign with some history behind it, so a round trip has work to do. */
function played(): Snapshot {
  const heat = createHeat(world.roads);
  const intel = createIntel(world.roads, world.extent);
  const front = createFront(1337, world.extent, world.spawn);
  const quests = createQuests();
  let condition = freshCondition();

  for (let m = 0; m < 400; m++) stepHeat(heat, { dt: 1 / 60, segmentId: 2, distance: 1 });
  for (let i = 0; i < 200; i++) {
    condition = applyWear(condition, { dt: 1 / 60, distance: 3, throttle: 1, impactForce: 3e4 });
  }
  observe(intel, heat, 2, 12);
  reveal(intel, world.spawn.x, world.spawn.z, 90, (x, z) => controlAt(front, x, z));
  intel.visitedNodes.add(9);
  for (let i = 0; i < 60 * 45; i++) stepFront(front, 1 / 60);
  applyMissionImpact(front, 18);
  quests.completed = 3;
  quests.parts = 0.42;
  quests.nextId = 7;

  return {
    seed: 1337,
    elapsed: 412.5,
    condition,
    car: { position: [12, 1.1, -30], rotation: [0, 0.3, 0, 0.95], linvel: [4, 0, 1], angvel: [0, 0.2, 0] },
    heat,
    intel,
    front,
    quests,
  };
}

/** A pristine campaign for the same world, to restore into. */
function blank(): Snapshot {
  const front = createFront(1337, world.extent, world.spawn);
  return {
    seed: 1337,
    elapsed: 0,
    condition: freshCondition(),
    car: { position: [0, 0, 0], rotation: [0, 0, 0, 1], linvel: [0, 0, 0], angvel: [0, 0, 0] },
    heat: createHeat(world.roads),
    intel: createIntel(world.roads, world.extent),
    front,
    quests: createQuests(),
  };
}

describe('save round trip', () => {
  it('survives JSON, which is what actually goes to storage', () => {
    const source = played();
    const restored = blank();
    const data = JSON.parse(JSON.stringify(serialise(source)));
    expect(isLoadable(data, 1337, world.roads.segments.length, restored.intel.explored.length)).toBe(
      true,
    );
    apply(data, restored);

    expect(restored.elapsed).toBe(source.elapsed);
    expect(restored.condition).toEqual(source.condition);
    expect(restored.car).toEqual(source.car);
    expect(restored.heat.value).toEqual(source.heat.value);
    expect(restored.heat.level).toEqual(source.heat.level);
    expect(restored.quests.completed).toBe(3);
    expect(restored.quests.parts).toBeCloseTo(0.42, 9);
  });

  it('brings back the ceiling, not just the current condition', () => {
    const source = played();
    const restored = blank();
    // Otherwise a reload would quietly undo every permanent bit of damage,
    // which is the one thing "decline, not reset" cannot survive.
    expect(source.condition.ceiling.chassis).toBeLessThan(1);
    apply(JSON.parse(JSON.stringify(serialise(source))), restored);
    expect(restored.condition.ceiling).toEqual(source.condition.ceiling);
  });

  it('restores what the player knew, including the parts that are wrong', () => {
    const source = played();
    const restored = blank();
    apply(JSON.parse(JSON.stringify(serialise(source))), restored);

    expect(restored.intel.seenAt).toEqual(source.intel.seenAt);
    expect(restored.intel.rememberedLevel).toEqual(source.intel.rememberedLevel);
    expect([...restored.intel.visitedNodes]).toEqual([...source.intel.visitedNodes]);
    expect(restored.intel.explored).toEqual(source.intel.explored);
    expect(restored.intel.rememberedControl).toEqual(source.intel.rememberedControl);
    expect(restored.intel.explored).toBeInstanceOf(Uint8Array);
  });

  it('puts the front back where the war had got to', () => {
    const source = played();
    const restored = blank();
    expect(controlAt(restored.front, 100, 100)).toBeDefined();
    apply(JSON.parse(JSON.stringify(serialise(source))), restored);
    stepFront(restored.front, 0);
    stepFront(source.front, 0);
    expect(restored.front.boundaries).toEqual(source.front.boundaries);
  });

  it('keeps an in-flight mission, so a save mid-run is not a lost run', () => {
    const source = played();
    source.quests.active = {
      id: 4,
      type: 'delivery',
      targetNode: 11,
      novel: true,
      route: { nodes: [1, 2], segments: [0], length: 120 },
      intel: { worst: 'patrol', unknownCount: 1, stalest: 30 },
      reward: 0.2,
      impact: 12,
      originBase: 1,
      stage: 'return',
      worked: 3,
    };
    const restored = blank();
    apply(JSON.parse(JSON.stringify(serialise(source))), restored);
    expect(restored.quests.active?.stage).toBe('return');
    expect(restored.quests.active?.targetNode).toBe(11);
  });
});

describe('save validation', () => {
  const segments = world.roads.segments.length;
  const cells = createIntel(world.roads, world.extent).explored.length;
  const good = () => JSON.parse(JSON.stringify(serialise(played())));

  it('accepts a save for this world', () => {
    expect(isLoadable(good(), 1337, segments, cells)).toBe(true);
  });

  it('rejects a save from a different world', () => {
    // Seeds define the map; loading one campaign's roads into another's world
    // would put checkpoints and memories on roads that do not exist.
    expect(isLoadable(good(), 999, segments, cells)).toBe(false);
  });

  it('rejects a save from an older format', () => {
    expect(isLoadable({ ...good(), version: SAVE_VERSION - 1 }, 1337, segments, cells)).toBe(false);
  });

  it('rejects a save whose arrays no longer match the generator', () => {
    // Changing world generation invalidates old saves. Refusing is correct:
    // a half-restored campaign is worse than a fresh one.
    expect(isLoadable(good(), 1337, segments + 1, cells)).toBe(false);
    expect(isLoadable(good(), 1337, segments, cells + 1)).toBe(false);
  });

  it('rejects junk without throwing', () => {
    for (const junk of [null, undefined, 42, 'save', {}, { version: SAVE_VERSION }]) {
      expect(isLoadable(junk, 1337, segments, cells)).toBe(false);
    }
  });
});