ttrpg_manager/src/lib/rules/rules.test.ts

import { describe, it, expect } from 'vitest';
import { abilityModifier } from './abilities';
import { dnd5e, proficiencyBonus } from './dnd5e';
import { pf2e, pf2eProficiency } from './pf2e';
import { pf2eSlots } from './pf2e/progression';
import { applyRest } from './rest';
import type { CharacterRulesInput } from './types';

describe('abilityModifier', () => {
  it.each([
    [10, 0],
    [11, 0],
    [12, 1],
    [8, -1],
    [20, 5],
    [1, -5],
    [30, 10],
  ])('score %i -> %i', (score, mod) => {
    expect(abilityModifier(score)).toBe(mod);
  });

  it('never returns NaN for garbage input', () => {
    expect(abilityModifier(Number.NaN)).toBe(0);
    expect(abilityModifier(Infinity)).toBe(0);
  });
});

describe('5e proficiency bonus', () => {
  it.each([
    [1, 2],
    [4, 2],
    [5, 3],
    [9, 4],
    [13, 5],
    [17, 6],
    [20, 6],
  ])('level %i -> +%i', (lvl, pb) => {
    expect(proficiencyBonus(lvl)).toBe(pb);
  });

  it('clamps out-of-range levels (old app gave +251 at level 1000)', () => {
    expect(proficiencyBonus(1000)).toBe(6);
    expect(proficiencyBonus(0)).toBe(2);
    expect(proficiencyBonus(-5)).toBe(2);
  });
});

describe('5e derived stats', () => {
  const input: CharacterRulesInput = {
    level: 5,
    abilities: { str: 16, dex: 14, con: 14, int: 10, wis: 12, cha: 8 },
    skillRanks: { athletics: 'trained', stealth: 'expert' },
    saveRanks: { str: 'trained', con: 'trained' },
  };

  it('adds proficiency to trained skills and double for expertise', () => {
    const skills = dnd5e.skillModifiers(input);
    const athletics = skills.find((s) => s.key === 'athletics')!;
    const stealth = skills.find((s) => s.key === 'stealth')!;
    const arcana = skills.find((s) => s.key === 'arcana')!;
    expect(athletics.modifier).toBe(3 + 3); // str mod + PB(5)=3
    expect(stealth.modifier).toBe(2 + 6); // dex mod + 2*PB
    expect(arcana.modifier).toBe(0); // untrained int
  });

  it('computes spell save DC', () => {
    expect(dnd5e.spellSaveDc!(input, 'wis')).toBe(8 + 3 + 1);
  });

  it('unarmored AC does not penalise below 10 + dex', () => {
    // regression: old app applied a phantom -1 from heavy armor DEX cap
    const ac = dnd5e.baseArmorClass(input);
    expect(ac).toBe(10 + 2);
  });

  it('heavy armor (dexCap 0) ignores a negative DEX rather than penalising AC', () => {
    // regression: Math.min(dexMod, 0) wrongly applied a negative DEX to heavy armor.
    const lowDex: CharacterRulesInput = {
      level: 1,
      abilities: { str: 16, dex: 8, con: 14, int: 10, wis: 12, cha: 8 }, // DEX 8 = -1
      equippedArmor: { baseAc: 18, dexCap: 0 }, // plate
    };
    expect(dnd5e.baseArmorClass(lowDex)).toBe(18); // not 17
  });
});

describe('pf2e proficiency', () => {
  it('adds level + rank bonus when trained, 0 when untrained', () => {
    expect(pf2eProficiency(5, 'untrained')).toBe(0);
    expect(pf2eProficiency(5, 'trained')).toBe(5 + 2);
    expect(pf2eProficiency(5, 'expert')).toBe(5 + 4);
    expect(pf2eProficiency(10, 'legendary')).toBe(10 + 8);
  });

  it('skill modifier folds in ability + proficiency', () => {
    const skills = pf2e.skillModifiers({
      level: 3,
      abilities: { str: 18, dex: 10, con: 12, int: 10, wis: 14, cha: 10 },
      skillRanks: { athletics: 'expert' },
    });
    const athletics = skills.find((s) => s.key === 'athletics')!;
    expect(athletics.modifier).toBe(4 + (3 + 4)); // str mod + (level + expert bonus)
  });

  it('only con/dex/wis are real saves', () => {
    const saves = pf2e.saveModifiers({
      level: 4,
      abilities: { str: 10, dex: 14, con: 16, int: 10, wis: 12, cha: 10 },
      saveRanks: { con: 'expert', dex: 'trained', wis: 'trained' },
    });
    expect(saves.con).toBe(3 + (4 + 4));
    expect(saves.dex).toBe(2 + (4 + 2));
    expect(saves.str).toBe(0); // not a save: just ability mod
  });

  it('AC scales with level + armor proficiency (not just 10 + Dex)', () => {
    // level-5 fighter, Dex +1, trained in defense, unarmored: 10 + 1 + (5 + 2) = 18
    const ac = pf2e.baseArmorClass({
      level: 5,
      abilities: { str: 18, dex: 12, con: 14, int: 10, wis: 12, cha: 10 },
      acRank: 'trained',
    });
    expect(ac).toBe(18);
  });

  it('weapon attack: potency adds to-hit only, never flat damage', () => {
    // level-3, STR 18 (+4), trained (3+2=+5), +1 potency, 1d8
    const r = pf2e.weaponAttack(
      { level: 3, abilities: { str: 18, dex: 10, con: 10, int: 10, wis: 10, cha: 10 } },
      { ability: 'str', rank: 'trained', itemBonus: 1, damageDice: '1d8' },
    );
    expect(r.toHit).toBe(4 + 5 + 1); // +10
    expect(r.damage).toBe('1d8+4'); // STR only — no +item on damage
  });

  it('weapon attack reports MAP (-5/-10, agile -4/-8) and striking dice', () => {
    const base = { level: 3, abilities: { str: 18, dex: 10, con: 10, int: 10, wis: 10, cha: 10 } };
    const sword = pf2e.weaponAttack(base, { ability: 'str', rank: 'trained', damageDice: '1d8', striking: 2 });
    expect(sword.toHit).toBe(9);
    expect(sword.map).toEqual({ second: 4, third: -1 }); // -5 / -10
    expect(sword.damage).toBe('2d8+4'); // striking doubles the dice
    const agile = pf2e.weaponAttack(base, { ability: 'str', rank: 'trained', damageDice: '1d6', agile: true });
    expect(agile.map).toEqual({ second: 5, third: 1 }); // -4 / -8
  });

  it('full caster has 2 first-rank slots at level 1, 3 from level 2', () => {
    expect(pf2eSlots('full', 1)).toEqual([{ level: 1, max: 2, current: 2 }]);
    expect(pf2eSlots('full', 2)).toEqual([{ level: 1, max: 3, current: 3 }]);
    // level 3: 3 first-rank + 2 (newly unlocked) second-rank
    expect(pf2eSlots('full', 3)).toEqual([
      { level: 1, max: 3, current: 3 },
      { level: 2, max: 2, current: 2 },
    ]);
  });
});

describe('pf2e Refocus', () => {
  it('restores one Focus Point, not the whole pool', () => {
    const refocus = pf2e.restOptions.find((o) => o.id === 'refocus')!;
    const c = {
      resources: [{ id: 'f', name: 'Focus Points', current: 0, max: 3, recovery: 'short' as const }],
      hp: { current: 10, max: 10, temp: 0 },
      concentration: null,
      spellcasting: { slots: [], spells: [] },
      defenses: { exhaustion: 0, deathSaves: { successes: 0, failures: 0 } },
    } as unknown as Parameters<typeof applyRest>[0];
    const patch = applyRest(c, refocus);
    expect(patch.resources?.[0]?.current).toBe(1); // +1, clamped to max — not 3
  });
});

describe('pf2e Rest for the Night', () => {
  it('decays drained/doomed, clears wounded/fatigued, and caps HP at the post-decay effective max', () => {
    const rest = pf2e.restOptions.find((o) => o.id === 'rest')!;
    const c = {
      system: 'pf2e', level: 6,
      resources: [],
      hp: { current: 5, max: 50, temp: 0 },
      concentration: null,
      spellcasting: { slots: [], spells: [] },
      conditions: [{ name: 'Drained', value: 2 }, { name: 'Fatigued' }],
      defenses: { exhaustion: 0, deathSaves: { successes: 0, failures: 0 }, dying: 0, wounded: 2, doomed: 1, heroPoints: 1, inspiration: false },
    } as unknown as Parameters<typeof applyRest>[0];
    const patch = applyRest(c, rest);
    expect(patch.conditions).toEqual([{ name: 'Drained', value: 1 }]); // drained −1, fatigued gone
    expect(patch.defenses!.wounded).toBe(0);
    expect(patch.defenses!.doomed).toBe(0);
    // drained 1 remains after decay → effective max 50 − 6 = 44, not 50
    expect(patch.hp!.current).toBe(44);
  });
});