import { describe, it, expect } from 'vitest';
import { natureMultiplier, statAt, calcDamage } from '../src/lib/damage-calc.js';

describe('natureMultiplier', () => {
  it('boosts, cuts, and no-ops', () => {
    expect(natureMultiplier('Adamant', 'atk')).toBe(1.1);
    expect(natureMultiplier('Adamant', 'spa')).toBe(0.9);
    expect(natureMultiplier('Adamant', 'spe')).toBe(1);
    expect(natureMultiplier('Hardy', 'atk')).toBe(1); // neutral nature
    expect(natureMultiplier('Nonsense', 'atk')).toBe(1); // unknown nature
  });
});

describe('statAt (Gen 3+ formula)', () => {
  it('HP and a normal stat at level 100, 31 IV / 0 EV / neutral', () => {
    // Garchomp: 108 base HP -> 357 ; 130 base Atk -> 296
    expect(statAt(108, 100, { statKey: 'hp' })).toBe(357);
    expect(statAt(130, 100, { statKey: 'atk' })).toBe(296);
  });

  it('applies nature to the raw stat', () => {
    expect(statAt(130, 100, { statKey: 'atk', nature: 'Adamant' })).toBe(325); // floor(296 * 1.1)
    expect(statAt(130, 100, { statKey: 'atk', nature: 'Modest' })).toBe(266); // floor(296 * 0.9)
  });

  it('Shedinja HP is always 1', () => {
    expect(statAt(1, 100, { statKey: 'hp' })).toBe(1);
  });
});

describe('calcDamage', () => {
  it('returns null for status / zero-power moves', () => {
    expect(calcDamage({ power: 0, level: 50 })).toBeNull();
    expect(calcDamage({ power: null, level: 50 })).toBeNull();
  });

  it('STAB + super effective, with the 85–100% roll', () => {
    const r = calcDamage({
      level: 100,
      power: 80,
      moveType: 'water',
      atkTypes: ['water'],
      defTypes: ['ground', 'rock'], // 4x
      atkStat: 200,
      defStat: 100,
      gen: 9,
    });
    expect(r.stab).toBe(true);
    expect(r.eff).toBe(4);
    expect(r.max).toBeGreaterThan(r.min);
    expect(r.min).toBeGreaterThanOrEqual(1);
  });

  it('immunity short-circuits to 0', () => {
    const r = calcDamage({
      level: 100,
      power: 100,
      moveType: 'ground',
      atkTypes: ['fire'], // no STAB, to keep the shape unambiguous
      defTypes: ['flying'],
      atkStat: 200,
      defStat: 100,
      gen: 9,
    });
    expect(r).toEqual({ min: 0, max: 0, stab: false, eff: 0 });
  });

  it('crit multiplier differs pre/post Gen 6', () => {
    const base = {
      level: 100,
      power: 100,
      moveType: 'normal',
      atkTypes: ['normal'],
      defTypes: ['normal'],
      atkStat: 200,
      defStat: 100,
      crit: true,
    };
    const g5 = calcDamage({ ...base, gen: 5 });
    const g6 = calcDamage({ ...base, gen: 6 });
    expect(g5.max).toBeGreaterThan(g6.max); // 2x vs 1.5x
  });
});