'use strict';

/**
 * THE SHADOW MUST BE GENERATED, PERSISTED, AND HARMLESS.
 *
 * A5's whole finding was a factor that was built, correct, and never invoked.
 * Evidence that is computed but never reaches a row is that same failure one
 * layer along — so this drives the REAL retention row builder rather than
 * asserting the merge function in isolation.
 */
const retention = require('../../src/services/retentionService');
const pc = require('../../src/services/model/probabilityContract');

const ERA = 'engine1@2026-08-07-fullwindow';
const iso = (p) => Math.round((0.42 + 0.26 * p) * 1000) / 1000;
const contract = {
  fit_n: 1798, fitted_through: '2026-08-17',
  resolve: (read) => pc.resolve({ ...read, sport: 'mlb', stat: 'hits' }, { estimate: iso }),
};

const row = (over) => ({
  player_key: 'x', stat: 'hits', line: 0.5, side: 'over', model_version: ERA,
  p_win: 0.65, confidence: 65, grade: 'C+', ev_pct: 12.3, value: true, takeable: true,
  book_odds: -115, over_odds: -115, under_odds: -105, probability_contract: null, ...over,
});

describe('the shadow reaches the row', () => {
  it('the REAL collector declares the column on every row, refusals included', () => {
    const collector = retention.createCollector({
      snapshotId: 'snap-1', sport: 'mlb', modelVersion: ERA, codeSha: 'test',
      gameDate: '2026-09-01', gameIdFor: () => 'mlb:2026-09-01:AAA@BBB',
    });
    collector.onGraded(
      { player: 'A Hitter', stat_type: 'hits', line: 0.5, sport: 'mlb',
        over_odds: -115, under_odds: -105 },
      [{ direction: 'over', grade: 'C+', p_win: 0.65, confidence: 65 },
       { direction: 'under', insufficient_data: true }],
    );
    // the collector is the real path; if it collected nothing the assertion
    // below would vacuously pass, so require the rows first
    expect(collector.rows.length).toBe(2);
    for (const r of collector.rows) expect('probability_contract' in r).toBe(true);
    const merged = retention.mergeProbabilityContract(collector.rows, contract);
    expect(merged.find((r) => r.side === 'over').probability_contract.probability_state)
      .toBe(pc.STATE.CERTIFIED_CALIBRATED);
  });

  it('every row in a batch carries the key — a partial shape drops the column for all', () => {
    const rows = [row(), row({ p_win: 0.91 }), row({ p_win: null, grade: null })];
    const out = retention.mergeProbabilityContract(rows, contract);
    expect(out).toHaveLength(3);
    for (const r of out) expect('probability_contract' in r).toBe(true);
  });

  it('records the served candidate inside support', () => {
    const [r] = retention.mergeProbabilityContract([row()], contract);
    expect(r.probability_contract.probability_state).toBe(pc.STATE.CERTIFIED_CALIBRATED);
    expect(r.probability_contract.served_probability).toBe(iso(0.65));
    expect(r.probability_contract.estimator_type).toBe('isotonic');
    expect(r.probability_contract.servable).toBe(false);
  });

  it('records the REFUSAL, and keeps the raw belief on it', () => {
    const [r] = retention.mergeProbabilityContract([row({ p_win: 0.91 })], contract);
    expect(r.probability_contract.probability_state).toBe(pc.STATE.UNCERTIFIED);
    expect(r.probability_contract.served_probability).toBeNull();
    expect(r.probability_contract.raw_model_probability).toBe(0.91);
    expect(r.probability_contract.derived.available).toBe(false);
  });

  it('prices the SIDE, not the opposite bet', () => {
    const { evPct } = require('../../src/utils/devig');
    const [o] = retention.mergeProbabilityContract([row({ side: 'over', book_odds: null })], contract);
    const [u] = retention.mergeProbabilityContract([row({ side: 'under', book_odds: null })], contract);
    expect(o.probability_contract.derived.ev_pct).toBe(evPct(iso(0.65), -115));
    expect(u.probability_contract.derived.ev_pct).toBe(evPct(iso(0.65), -105));
  });
});

describe('the shadow changes NOTHING that is served', () => {
  it('leaves EVERY key byte-identical except probability_contract', () => {
    // Diffing a NAMED LIST of served fields only proves the fields someone
    // thought to list. Diff every key, so a field added later is covered by
    // this test on the day it appears.
    const before = [row(), row({ p_win: 0.91, grade: 'B+' }), row({ side: 'under', p_win: 0.55 }),
      row({ p_win: null, grade: null }), row({ model_version: 'engine1@2026-07-20' })];
    const snapshot = JSON.parse(JSON.stringify(before));
    const after = retention.mergeProbabilityContract(before, contract);
    after.forEach((r, i) => {
      const keys = new Set([...Object.keys(r), ...Object.keys(snapshot[i])]);
      keys.delete('probability_contract');
      expect(keys.size).toBeGreaterThan(8);          // the diff must be non-vacuous
      for (const k of keys) expect(r[k]).toEqual(snapshot[i][k]);
    });
  });

  it('adds exactly ONE key and no others', () => {
    const before = row();
    const after = retention.mergeProbabilityContract([before], contract)[0];
    const added = Object.keys(after).filter((k) => !(k in before));
    const removed = Object.keys(before).filter((k) => !(k in after));
    expect(added).toEqual([]);                        // declared null upfront
    expect(removed).toEqual([]);
    expect(after.probability_contract).not.toBeNull();
  });

  it('does not mutate the input rows in place', () => {
    const rows = [row()];
    retention.mergeProbabilityContract(rows, contract);
    expect(rows[0].probability_contract).toBeNull();
  });

  it('a null contract is a no-op, not a raw passthrough', () => {
    const out = retention.mergeProbabilityContract([row()], null);
    expect(out[0].probability_contract).toBeNull();
  });

  it('a throwing contract leaves the row intact rather than losing it', () => {
    const bad = { resolve: () => { throw new Error('boom'); } };
    const out = retention.mergeProbabilityContract([row()], bad);
    expect(out).toHaveLength(1);
    expect(out[0].p_win).toBe(0.65);
    expect(out[0].probability_contract).toBeNull();
  });
});

describe('the flag is OFF by default', () => {
  it('snapshotService reads PROBABILITY_CONTRACT_SHADOW and defaults to off', () => {
    const src = require('fs').readFileSync(
      require('path').join(__dirname, '../../src/services/snapshotService.js'), 'utf8');
    expect(src).toContain("process.env.PROBABILITY_CONTRACT_SHADOW || '') === '1'");
    // and it must not be able to write a served field
    const block = src.slice(src.indexOf('PROBABILITY CONTRACT SHADOW'), src.indexOf('let lineageIndex'));
    for (const served of ['g.p_win =', 'g.confidence =', 'g.grade =', 'g.ev_pct =', 'g.value =']) {
      expect(block).not.toContain(served);
    }
  });

  it('nothing is added to CALIBRATION_DEPLOYED', () => {
    const src = require('fs').readFileSync(
      require('path').join(__dirname, '../../src/services/snapshotService.js'), 'utf8');
    expect(src).toMatch(/CALIBRATION_DEPLOYED\s*=\s*Object\.freeze\(\[\s*\]\)/);
  });
});

describe('the artifact must agree with the contract, not merely accompany it', () => {
  const cal = require('../../src/services/model/calibration');
  const svc = require('../../src/services/model/probabilityContractService');
  const map = cal.fitIsotonic(Array.from({ length: 900 }, (_, i) => {
    const p = Math.round((0.35 + (i % 60) / 100) * 1000) / 1000;
    return { p, won: ((i * 2654435761) % 1000) / 1000 < (0.5 + 0.45 * (p - 0.5)) ? 1 : 0, date: `d${i % 14}` };
  }), { minTotal: 200 });
  const build = () => svc.build({}, { calibrationService: { fromLedger: async () => ({
    map, fit_n: 900, fitted_through: '2026-08-21', cutoff: '2026-09-02' }) } });

  it('the built artifact declares the CERTIFIED era and estimator', async () => {
    const b = await build();
    expect(b.artifact.model_version).toBe(pc.MLB_HITS.model_version);
    expect(b.artifact.estimator_type).toBe(pc.MLB_HITS.estimator_type);
  });

  it('an artifact fitted for another era serves NOTHING, even on a matching read', () => {
    const r = pc.resolve({ sport: 'mlb', stat: 'hits', model_version: ERA, p_win: 0.65 },
      { estimate: () => 0.6, artifact: { model_version: 'engine1@2026-07-20', estimator_type: 'isotonic' } });
    expect(r.probability_state).toBe(pc.STATE.VERSION_MISMATCH);
    expect(r.served_probability).toBeNull();
  });

  it('an artifact of the wrong estimator type serves NOTHING', () => {
    const r = pc.resolve({ sport: 'mlb', stat: 'hits', model_version: ERA, p_win: 0.65 },
      { estimate: () => 0.6, artifact: { model_version: ERA, estimator_type: 'low_param' } });
    expect(r.probability_state).toBe(pc.STATE.VERSION_MISMATCH);
    expect(r.served_probability).toBeNull();
  });

  it('and the row records the mismatch rather than dropping it', () => {
    const bad = { fit_n: 1, fitted_through: 'x',
      resolve: (read) => pc.resolve({ ...read, sport: 'mlb', stat: 'hits' },
        { estimate: () => 0.6, artifact: { model_version: 'engine1@2026-07-20', estimator_type: 'isotonic' } }) };
    const [r] = retention.mergeProbabilityContract([row()], bad);
    expect(r.probability_contract.probability_state).toBe(pc.STATE.VERSION_MISMATCH);
    expect(r.probability_contract.served_probability).toBeNull();
    expect(r.probability_contract.raw_model_probability).toBe(0.65);
  });
});