'use strict';

/**
 * THE INVARIANT: artifact.model_version = X => distinct(training.model_version) = {X}.
 */
const src = require('../../src/services/model/currentEraSource');

const ERA = 'engine1@2026-08-07-fullwindow';
const OLD = 'engine1@2026-07-20';

/** A fake that HONOURS its filters — a pass-through would prove nothing. */
function client(rows) {
  const f = {};
  const q = {
    select: () => q,
    eq: (c, v) => { f[c] = v; return q; },
    is: () => q,
    in: (c, v) => { f[`in_${c}`] = v; return q; },
    not: () => q,
    lt: (c, v) => { f[`lt_${c}`] = v; return q; },
    order: () => q,
    range: async () => {
      let out = rows;
      for (const [k, v] of Object.entries(f)) {
        if (k.startsWith('in_') || k.startsWith('lt_')) continue;
        out = out.filter((r) => r[k] === v);
      }
      if (f.lt_game_date) out = out.filter((r) => r.game_date < f.lt_game_date);
      return { data: out, error: null, count: out.length };
    },
  };
  return { client: { from: () => q }, filters: f };
}

const ROWS = [
  { id: '1', p_win: 0.6, outcome: 'hit', game_date: '2026-08-12', model_version: ERA, sport: 'mlb', stat: 'hits' },
  { id: '2', p_win: 0.7, outcome: 'miss', game_date: '2026-08-13', model_version: ERA, sport: 'mlb', stat: 'hits' },
  { id: '3', p_win: 0.55, outcome: 'hit', game_date: '2026-08-01', model_version: OLD, sport: 'mlb', stat: 'hits' },
];

describe('the era restriction is in the QUERY', () => {
  it('loads only the requested era', async () => {
    const { client: c, filters } = client(ROWS);
    const out = await src.loadRows(c, { sport: 'mlb', stat: 'hits', modelVersion: ERA, before: '2026-09-03' });
    expect(filters.model_version).toBe(ERA);
    expect(out.map((r) => r.id).sort()).toEqual(['1', '2']);
    expect(out.every((r) => r.model_version === ERA)).toBe(true);
  });

  it('the era audit is computed from the ACTUAL rows, not a second query', () => {
    const mixed = [{ model_version: ERA }, { model_version: ERA }, { model_version: OLD }];
    const a = src.eraAudit(mixed, ERA);
    expect(a.current_era_rows).toBe(2);
    expect(a.wrong_era_rows).toBe(1);
    expect(src.eraAudit([{ model_version: ERA }], ERA).wrong_era_rows).toBe(0);
  });

  it('refuses to run without an explicit era and horizon', async () => {
    const { client: c } = client(ROWS);
    await expect(src.loadRows(c, { sport: 'mlb', stat: 'hits', before: '2026-09-03' })).rejects.toThrow();
    await expect(src.loadRows(c, { sport: 'mlb', stat: 'hits', modelVersion: ERA })).rejects.toThrow();
  });
});

describe('the source digest', () => {
  const R = [
    { id: 'b', p: 0.6, won: 1, date: 'd2', model_version: ERA },
    { id: 'a', p: 0.5, won: 0, date: 'd1', model_version: ERA },
  ];
  const base = src.sourceDigest(R);

  it('ignores database return order', () => {
    expect(src.sourceDigest([...R].reverse())).toBe(base);
  });

  it('moves when a row is added, removed, or materially changed', () => {
    expect(src.sourceDigest([R[0]])).not.toBe(base);
    expect(src.sourceDigest([...R, { id: 'c', p: 0.7, won: 1, date: 'd3', model_version: ERA }])).not.toBe(base);
    expect(src.sourceDigest([{ ...R[0], won: 0 }, R[1]])).not.toBe(base);
    expect(src.sourceDigest([{ ...R[0], p: 0.61 }, R[1]])).not.toBe(base);
    expect(src.sourceDigest([{ ...R[0], model_version: OLD }, R[1]])).not.toBe(base);
    expect(src.sourceDigest([{ ...R[0], date: 'd9' }, R[1]])).not.toBe(base);
  });
});