import { describe, it, expect } from 'vitest';
import { World } from '../../ecs/World.js';
import { statModifierSystem } from '../statModifierSystem.js';
import type { Stats, StatModifiers, Needs } from '@dflike/shared';

function setupEntity(
  world: World,
  statsOverrides: Partial<Stats> = {},
  needs?: Partial<Needs>,
  modifiers: StatModifiers['modifiers'] = [],
): number {
  const e = world.createEntity();
  const base: Stats = {
    strength: 10, dexterity: 10, constitution: 10, intelligence: 10, perception: 10,
    sociability: 10, courage: 10, curiosity: 10, empathy: 10, temperament: 10,
    ...statsOverrides,
  };
  world.addComponent<Stats>(e, 'stats', base);
  world.addComponent<StatModifiers>(e, 'statModifiers', { modifiers: [...modifiers] });
  if (needs) {
    world.addComponent<Needs>(e, 'needs', { hunger: 80, energy: 80, ...needs });
  }
  return e;
}

describe('statModifierSystem', () => {
  describe('modifier decay', () => {
    it('decrements remaining on each modifier', () => {
      const world = new World();
      const e = setupEntity(world, {}, undefined, [
        { stat: 'strength', value: 2, remaining: 10 },
      ]);
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      expect(mods.modifiers[0].remaining).toBe(9);
    });

    it('removes expired modifiers (remaining reaches 0)', () => {
      const world = new World();
      const e = setupEntity(world, {}, undefined, [
        { stat: 'strength', value: 2, remaining: 1 },
        { stat: 'dexterity', value: -1, remaining: 5 },
      ]);
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      expect(mods.modifiers).toHaveLength(1);
      expect(mods.modifiers[0].stat).toBe('dexterity');
    });

    it('does not decrement permanent modifiers (remaining = -1)', () => {
      const world = new World();
      const e = setupEntity(world, {}, undefined, [
        { stat: 'intelligence', value: -2, remaining: -1 },
      ]);
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      expect(mods.modifiers[0].remaining).toBe(-1);
    });
  });

  describe('needs-based modifiers', () => {
    it('applies intelligence -2 and sociability -1 when hunger < 30', () => {
      const world = new World();
      const e = setupEntity(world, {}, { hunger: 20, energy: 80 });
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      const intMod = mods.modifiers.find(m => m.stat === 'intelligence' && m.remaining === -1);
      const socMod = mods.modifiers.find(m => m.stat === 'sociability' && m.remaining === -1);
      expect(intMod?.value).toBe(-2);
      expect(socMod?.value).toBe(-1);
    });

    it('applies dexterity -2 and temperament -2 when energy < 20', () => {
      const world = new World();
      const e = setupEntity(world, {}, { hunger: 80, energy: 10 });
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      const dexMod = mods.modifiers.find(m => m.stat === 'dexterity' && m.remaining === -1);
      const tempMod = mods.modifiers.find(m => m.stat === 'temperament' && m.remaining === -1);
      expect(dexMod?.value).toBe(-2);
      expect(tempMod?.value).toBe(-2);
    });

    it('removes needs-based modifiers when needs recover', () => {
      const world = new World();
      const e = setupEntity(world, {}, { hunger: 20, energy: 80 });
      statModifierSystem(world);
      // Now hunger recovers
      const needs = world.getComponent<Needs>(e, 'needs')!;
      needs.hunger = 80;
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      const needsMods = mods.modifiers.filter(m => m.remaining === -1);
      expect(needsMods).toHaveLength(0);
    });

    it('does not stack needs-based modifiers across ticks', () => {
      const world = new World();
      const e = setupEntity(world, {}, { hunger: 20, energy: 80 });
      statModifierSystem(world);
      statModifierSystem(world);
      statModifierSystem(world);
      const mods = world.getComponent<StatModifiers>(e, 'statModifiers')!;
      const intMods = mods.modifiers.filter(m => m.stat === 'intelligence' && m.remaining === -1);
      expect(intMods).toHaveLength(1);
    });
  });
});