import { describe, it, expect } from 'vitest';
import { createWorld, advance } from '../src/sim/world.js';

describe('world', () => {
  it('creates a populated world with player at a planet', () => {
    const w = createWorld('alpha', { systemCount: 12, npcCount: 30 });
    expect(w.npcs).toHaveLength(30);
    expect(w.galaxy.systems).toHaveLength(12);
    expect(w.player.loc.kind).toBe('docked');
    expect(w.player.credits).toBeGreaterThan(0);
    for (const npc of w.npcs) {
      expect(npc.alive).toBe(true);
      expect(w.galaxy.planets[npc.planetId]).toBeTruthy();
    }
  });

  it('advance processes events; NPCs actually trade', () => {
    const w = createWorld('alpha', { systemCount: 12, npcCount: 30 });
    advance(w, 40);
    expect(w.t).toBe(40);
    expect(w.stats.trades).toBeGreaterThan(30); // every npc averages >1 completed trade
  });

  it('is deterministic end-to-end', () => {
    const run = () => {
      const w = createWorld('alpha', { systemCount: 12, npcCount: 30 });
      advance(w, 40);
      return w.npcs.map((n) => [n.credits, n.planetId, n.alive]);
    };
    expect(JSON.stringify(run())).toBe(JSON.stringify(run()));
  });

  it('different seeds diverge', () => {
    const w1 = createWorld('alpha', { systemCount: 12, npcCount: 30 });
    const w2 = createWorld('beta', { systemCount: 12, npcCount: 30 });
    advance(w1, 20);
    advance(w2, 20);
    expect(JSON.stringify(w1.npcs.map((n) => n.credits)))
      .not.toBe(JSON.stringify(w2.npcs.map((n) => n.credits)));
  });

  it('advance is incremental: many small steps equal one big step', () => {
    const a = createWorld('alpha', { systemCount: 12, npcCount: 30 });
    const b = createWorld('alpha', { systemCount: 12, npcCount: 30 });
    advance(a, 20);
    for (let t = 0.5; t <= 20.0001; t += 0.5) advance(b, t);
    expect(JSON.stringify(b.npcs.map((n) => [n.credits, n.planetId])))
      .toBe(JSON.stringify(a.npcs.map((n) => [n.credits, n.planetId])));
  });
});