import { describe, it, expect } from 'vitest';
import { ok, err } from '@shared/kernel/fp';
import { expectTag } from '@shared/testing/expect-tag';
import {
  initial,
  STEPS,
  lageUren,
  currentStep,
  next,
  back,
  gaNaarStap,
  submit,
  primary,
  resolve,
  reduce,
  IntakeState,
} from './intake.machine';
import { givenIntake } from './intake.testing';

describe('STEPS (fixed) and inline questions', () => {
  it('always has the same three steps', () => {
    expect(STEPS).toEqual(['buitenland', 'werk', 'review']);
  });

  it('reveals the buitenland detail questions inline only when worked abroad', () => {
    // No new step; instead these fields become required within the buitenland step.
    const abroad = givenIntake({ tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'ja' });
    expect(next(abroad).tag).toBe('Answering'); // land/uren missing -> blocked
    expect(expectTag(next(abroad), 'Answering').errors.land).toBeTruthy();
    const domestic = givenIntake({ tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' });
    expect(next(domestic).tag).toBe('Answering'); // valid, advances (cursor moves)
    expect(expectTag(next(domestic), 'Answering').cursor).toBe(1);
  });

  it('reveals the scholing question only when NL-hours are below the threshold', () => {
    expect(lageUren({ uren: '500' })).toBe(true);
    expect(lageUren({ uren: '4160' })).toBe(false);
  });

  it('uses the (server-owned) threshold passed in, not a hardcoded constant', () => {
    // Same hours, different threshold → different visibility. Proves de-hardcoding.
    expect(lageUren({ uren: '1500' }, 1000)).toBe(false);
    expect(lageUren({ uren: '1500' }, 2000)).toBe(true);
    // And the threshold from state flows through submit:
    const lowThresholdState = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '1500' },
      { tag: 'SetAnswer', key: 'punten', value: '200' },
      { tag: 'SetPolicy', scholingThreshold: 2000 },
    );
    const lowThreshold = submit(lowThresholdState);
    expect(lowThreshold.tag).toBe('Answering'); // scholing now required (1500 < 2000), unanswered → blocked
    expect(expectTag(lowThreshold, 'Answering').errors.scholingGevolgd).toBeTruthy();
  });
});

describe('navigation', () => {
  it('Next is a no-op (sets an error) when the current step is invalid', () => {
    const s = expectTag(next(initial), 'Answering'); // buitenland unanswered
    expect(s.cursor).toBe(0);
    expect(s.errors.buitenlandGewerkt).toBeTruthy();
  });

  it('Next advances once the step is valid', () => {
    const domestic = givenIntake({ tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' });
    const s = expectTag(next(domestic), 'Answering');
    expect(s.cursor).toBe(1);
    expect(currentStep(s)).toBe('werk');
  });

  it('editing an answer leaves the cursor fixed (steps never collapse)', () => {
    const atWerk = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'ja' },
      { tag: 'SetAnswer', key: 'land', value: 'België' },
      { tag: 'SetAnswer', key: 'buitenlandseUren', value: '300' },
      { tag: 'Next' }, // buitenland step valid -> cursor 0 -> 1
    );
    const edited = expectTag(
      reduce(atWerk, { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' }),
      'Answering',
    );
    expect(edited.cursor).toBe(1); // cursor untouched; only inline questions change
  });

  it('Back never goes below the first step', () => {
    expect(back(initial)).toBe(initial);
  });

  it('gaNaarStap jumps back to an earlier step, clearing errors', () => {
    const s = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'Next' }, // cursor 0 -> 1
      { tag: 'SetAnswer', key: 'uren', value: '4160' },
      { tag: 'Next' }, // cursor 1 -> 2
    );
    expect(expectTag(gaNaarStap(s, 0), 'Answering').cursor).toBe(0);
  });

  it('gaNaarStap ignores a same/forward jump and jumps outside Answering', () => {
    const s = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'Next' }, // cursor 0 -> 1
    );
    expect(gaNaarStap(s, 1)).toBe(s); // same step -> no-op
    expect(gaNaarStap(s, 2)).toBe(s); // forward -> no-op
    const atReview = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'Next' }, // cursor 0 -> 1
      { tag: 'SetAnswer', key: 'uren', value: '4160' },
      { tag: 'Next' }, // cursor 1 -> 2
    );
    const submitting = submit(atReview);
    expect(gaNaarStap(submitting, 0)).toBe(submitting); // not Answering -> no-op
  });
});

describe('submit', () => {
  // High hours: no scholing question, so no punten is asked or collected.
  const highUren = givenIntake(
    { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
    { tag: 'SetAnswer', key: 'uren', value: '4160' },
  );

  it('reaches Submitting ONLY with valid answers', () => {
    // Bad punten only blocks when scholing was followed (otherwise punten is ignored).
    const badPunten = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'ja' },
      { tag: 'SetAnswer', key: 'punten', value: 'x' },
    );
    expect(submit(badPunten).tag).toBe('Answering');
    const good = expectTag(submit(highUren), 'Submitting');
    expect(good.data.uren).toBe(4160);
    expect(good.data.punten).toBeUndefined(); // not collected without scholing
  });

  it('punten is required only when aanvullende scholing was gevolgd', () => {
    // scholing = ja but punten missing -> blocked on punten.
    const scholingJaNoPunten = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'ja' },
    );
    const missing = expectTag(submit(scholingJaNoPunten), 'Answering');
    expect(missing.errors.punten).toBeTruthy();
    // scholing = nee -> punten not required, submits without it.
    const scholingNee = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'nee' },
    );
    expect(submit(scholingNee).tag).toBe('Submitting');
  });

  it('low hours requires the scholing answer before submit', () => {
    const lowUrenNoScholing = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '500' },
    );
    const noScholing = submit(lowUrenNoScholing);
    expect(noScholing.tag).toBe('Answering'); // scholing question is required, unanswered
    const lowUrenWithScholing = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'ja' },
      { tag: 'SetAnswer', key: 'punten', value: '200' },
    );
    const withScholing = expectTag(submit(lowUrenWithScholing), 'Submitting');
    expect(withScholing.data.aanvullendeScholing).toBe(true);
    expect(withScholing.data.punten).toBe(200);
  });

  it('does not require punten for a hidden question', () => {
    // scholingGevolgd is a stale 'ja' from when uren was low, but uren is now above
    // threshold — the template hides the question, so punten must not be required either.
    const staleScholingNoPunten = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '1500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'ja' },
    );
    const good = expectTag(submit(staleScholingNoPunten), 'Submitting');
    expect(good.data.aanvullendeScholing).toBeUndefined();
  });

  it('drops punten when raising uren hides the question', () => {
    // Same stale answer, but this time punten was also filled in while uren was low.
    const staleScholingWithPunten = givenIntake(
      { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
      { tag: 'SetAnswer', key: 'uren', value: '1500' },
      { tag: 'SetAnswer', key: 'scholingGevolgd', value: 'ja' },
      { tag: 'SetAnswer', key: 'punten', value: '150' },
    );
    const good = expectTag(submit(staleScholingWithPunten), 'Submitting');
    // ValidIntake stays honest: neither the stale 'ja' nor its punten leak through.
    expect(good.data.aanvullendeScholing).toBeUndefined();
    expect(good.data.punten).toBeUndefined();
  });

  it('resolve maps Submitting to Submitted on a successful submit', () => {
    const submitting = submit(highUren);
    expect(resolve(submitting, ok(undefined)).tag).toBe('Submitted');
  });

  it('resolve maps Submitting to Failed on a failed submit', () => {
    const submitting = submit(highUren);
    expect(resolve(submitting, err('boom')).tag).toBe('Failed');
  });
});

describe('primary', () => {
  // Same fixture as the 'submit' describe block above: buitenland answered 'nee',
  // uren high enough to skip the scholing question.
  const highUren = givenIntake(
    { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'nee' },
    { tag: 'SetAnswer', key: 'uren', value: '4160' },
  );

  it('Primary advances to the next step from a non-final step', () => {
    expect(currentStep(expectTag(highUren, 'Answering'))).toBe('buitenland'); // not the final step
    expect(reduce(highUren, { tag: 'Primary' })).toEqual(reduce(highUren, { tag: 'Next' }));
    expect(expectTag(primary(highUren), 'Answering').cursor).toBe(1);
  });

  it('Primary submits from the final step', () => {
    const atReview = reduce(reduce(highUren, { tag: 'Next' }), { tag: 'Next' });
    expect(currentStep(expectTag(atReview, 'Answering'))).toBe('review'); // the final step
    expect(reduce(atReview, { tag: 'Primary' })).toEqual(reduce(atReview, { tag: 'Submit' }));
    expect(primary(atReview).tag).toBe('Submitting');
  });

  it('Primary is a no-op from a non-editing state', () => {
    const submitting = submit(reduce(reduce(highUren, { tag: 'Next' }), { tag: 'Next' }));
    expect(primary(submitting)).toBe(submitting);
  });
});

describe('reduce (message-driven happy path)', () => {
  it('drives abroad branch end to end', () => {
    let s: IntakeState = initial;
    // Step 1: buitenland — the country/hours questions reveal inline (same step).
    s = reduce(s, { tag: 'SetAnswer', key: 'buitenlandGewerkt', value: 'ja' });
    s = reduce(s, { tag: 'SetAnswer', key: 'land', value: 'België' });
    s = reduce(s, { tag: 'SetAnswer', key: 'buitenlandseUren', value: '800' });
    s = reduce(s, { tag: 'Next' });
    expect(currentStep(expectTag(s, 'Answering'))).toBe('werk');
    // Step 2: werk — uren + punten (no inline scholing, hours are high).
    s = reduce(s, { tag: 'SetAnswer', key: 'uren', value: '4160' });
    s = reduce(s, { tag: 'SetAnswer', key: 'punten', value: '200' });
    s = reduce(s, { tag: 'Next' });
    expect(currentStep(expectTag(s, 'Answering'))).toBe('review');
    s = reduce(s, { tag: 'Submit' });
    expect(s.tag).toBe('Submitting');
    s = reduce(s, { tag: 'SubmitConfirmed' });
    expect(s.tag).toBe('Submitted');
  });
});