import { describe, it, expect } from 'bun:test';
import { World } from '@common/rpg/core/world';
import { Stat } from '@common/rpg/components/stat';
import { Effect, EffectTemplate } from '@common/rpg/components/effect';
import { EffectSystem } from '@common/rpg/systems/effect';

function world() {
    const w = new World();
    w.addSystem(new EffectSystem());
    return w;
}

function withStat(value = 10, min?: number, max?: number) {
    const w = world();
    const e = w.createEntity();
    e.add('str', new Stat({ value, min, max }));
    return { w, e, stat: e.get(Stat, 'str')! };
}

describe('Effect — onAdd / onRemove', () => {
    it('applies delta to stat on add', () => {
        const { e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5 }));
        expect(stat.value).toBe(15);
    });

    it('reverts delta on remove', () => {
        const { e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5 }));
        e.remove('fx');
        expect(stat.value).toBe(10);
    });

    it('applies delta to max field', () => {
        const { e } = withStat(10, undefined, 20);
        const s = e.get(Stat, 'str')!;
        e.add('fx', new Effect({ targetStat: 'str', delta: 10, targetField: 'max' }));
        expect(s.max).toBe(30);
        e.remove('fx');
        expect(s.max).toBe(20);
    });

    it('active is true after add', () => {
        const { e } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 1 }));
        expect(e.get(Effect, 'fx')!.active).toBeTrue();
    });

    it('no-op if target stat is missing', () => {
        const w = world();
        const e = w.createEntity();
        expect(() => e.add('fx', new Effect({ targetStat: 'str', delta: 5 }))).not.toThrow();
    });
});

describe('Effect — duration', () => {
    it('expires after duration ticks', () => {
        const { w, e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5, duration: 2 }));
        expect(stat.value).toBe(15);

        w.update(1);
        expect(e.has(Effect)).toBeTrue();

        w.update(1);
        expect(e.has(Effect)).toBeFalse();
        expect(stat.value).toBe(10);
    });

    it('emits expired before removal', () => {
        const { w, e } = withStat(10);
        e.add(new Effect({ targetStat: 'str', delta: 1, duration: 1 }));
        const events: string[] = [];
        e.on('Effect.expired', () => events.push('expired'));
        w.update(1);
        expect(events).toEqual(['expired']);
    });

    it('reset() restarts timer', () => {
        const { w, e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5, duration: 2 }));
        w.update(1.5);
        e.get(Effect, 'fx')!.reset();
        w.update(1.5); // would have expired without reset
        expect(e.has(Effect)).toBeTrue();
        expect(stat.value).toBe(15);
    });

    it('reset(duration) changes duration', () => {
        const { w, e } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5, duration: 1 }));
        e.get(Effect, 'fx')!.reset(10);
        w.update(5);
        expect(e.has(Effect)).toBeTrue();
    });

    it('clear() immediately expires effect', () => {
        const { w, e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5, duration: 100 }));
        e.get(Effect, 'fx')!.clear();
        w.update(0.01);
        expect(e.has(Effect)).toBeFalse();
        expect(stat.value).toBe(10);
    });
});

describe('Effect — permanent', () => {
    it('permanent effect is never removed by EffectSystem', () => {
        const { w, e, stat } = withStat(10);
        e.add('fx', new Effect({ targetStat: 'str', delta: 5 }));
        w.update(100);
        expect(e.has(Effect)).toBeTrue();
        expect(stat.value).toBe(15);
    });
});

describe('Effect — scope: onHit', () => {
    it('onAdd is a no-op for onHit scope', () => {
        const { e, stat } = withStat(10);
        e.add('fx', new EffectTemplate({ targetStat: 'str', delta: 99 }));
        expect(stat.value).toBe(10);
    });

    it('onRemove is a no-op for onHit scope', () => {
        const { e, stat } = withStat(10);
        e.add('fx', new EffectTemplate({ targetStat: 'str', delta: 99 }));
        e.remove('fx');
        expect(stat.value).toBe(10);
    });

    it('EffectSystem does not tick or remove onHit effects', () => {
        const { w, e } = withStat(10);
        e.add('fx', new EffectTemplate({ targetStat: 'str', delta: 5, duration: 1 }));
        w.update(10);
        expect(e.has(EffectTemplate)).toBeTrue();
    });
});

describe('Effect — multiple effects on same stat', () => {
    it('multiple effects stack additively', () => {
        const { e, stat } = withStat(10);
        e.add('a', new Effect({ targetStat: 'str', delta: 3 }));
        e.add('b', new Effect({ targetStat: 'str', delta: 7 }));
        expect(stat.value).toBe(20);
    });

    it('removing one effect reverts only that delta', () => {
        const { e, stat } = withStat(10);
        e.add('a', new Effect({ targetStat: 'str', delta: 3 }));
        e.add('b', new Effect({ targetStat: 'str', delta: 7 }));
        e.remove('a');
        expect(stat.value).toBe(17);
    });
});