#!/usr/bin/env node
'use strict';
/**
 * certify-current-era-procedure — prove the REFIT PROCEDURE on current-era rows only.
 *
 * The prior certification pooled model eras. It does not substitute for this:
 * a procedure restricted to one forecaster has to earn its own proof, on that
 * forecaster's observations, walk-forward.
 *
 *   SUPABASE_URL=... SUPABASE_SERVICE_KEY=... node scripts/certify-current-era-procedure.js
 */
require('dotenv').config({ quiet: true });
const { createClient } = require('@supabase/supabase-js');
const cal = require('../src/services/model/calibration');
const src = require('../src/services/model/currentEraSource');
const { MODEL_VERSION } = require('../src/config/modelVersion');

const SPORT = 'mlb';
const STAT = 'hits';
const SUPPORT = [0.50, 0.80];
const PROBES = [0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.79];
const MIN_FIT = 200;
const FOLD_DATES = Number(process.env.FOLD_DATES || 3);   // eval block width
const FOLDS = Number(process.env.FOLDS || 4);

const r3 = (v) => (v == null || !Number.isFinite(v) ? null : Math.round(v * 1000) / 1000);
const r5 = (v) => (v == null || !Number.isFinite(v) ? null : Math.round(v * 100000) / 100000);
const inSupport = (p) => p >= SUPPORT[0] && p < SUPPORT[1];

const brier = (ps, ys) => (ps.length ? ps.reduce((s, p, i) => s + (p - ys[i]) ** 2, 0) / ps.length : null);
function logloss(ps, ys) { const E = 1e-12; let s = 0;
  for (let i = 0; i < ps.length; i++) { const p = Math.min(1 - E, Math.max(E, ps[i]));
    s += -(ys[i] * Math.log(p) + (1 - ys[i]) * Math.log(1 - p)); } return ps.length ? s / ps.length : null; }
function ece(ps, ys, bins = 10) { const a = Array.from({ length: bins }, () => ({ n: 0, sp: 0, sy: 0 }));
  for (let i = 0; i < ps.length; i++) { const b = Math.min(bins - 1, Math.floor(ps[i] * bins));
    a[b].n++; a[b].sp += ps[i]; a[b].sy += ys[i]; }
  let e = 0; for (const b of a) if (b.n) e += (b.n / ps.length) * Math.abs(b.sp / b.n - b.sy / b.n); return e; }
function wilson(k, n, z = 1.96) { if (!n) return null; const p = k / n, d = 1 + z * z / n;
  const c = (p + z * z / (2 * n)) / d, h = (z * Math.sqrt(p * (1 - p) / n + z * z / (4 * n * n))) / d;
  return [Math.max(0, c - h), Math.min(1, c + h)]; }
function pairedCI(a, b, ys, iters = 2000, seed = 17) { let s = seed >>> 0;
  const rnd = () => { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  const n = ys.length, out = [];
  for (let it = 0; it < iters; it++) { let sa = 0, sb = 0;
    for (let i = 0; i < n; i++) { const j = Math.floor(rnd() * n); sa += (a[j] - ys[j]) ** 2; sb += (b[j] - ys[j]) ** 2; }
    out.push(sa / n - sb / n); }
  out.sort((x, y) => x - y); return [out[Math.floor(iters * 0.025)], out[Math.floor(iters * 0.975)]]; }
const summ = (a) => { if (!a.length) return { support: 0 };
  const s = [...a].sort((x, y) => x - y); const q = (f) => s[Math.min(s.length - 1, Math.floor(s.length * f))];
  return { support: s.length, median: r3(q(0.5)), min: r3(s[0]), max: r3(s[s.length - 1]),
    iqr: r3(q(0.75) - q(0.25)), spread: r3(s[s.length - 1] - s[0]) }; };

(async () => {
  const sb = createClient(process.env.SUPABASE_URL, process.env.SUPABASE_SERVICE_KEY,
    { auth: { persistSession: false } });
  const today = process.env.FIT_AS_OF || new Date().toISOString().slice(0, 10);

  const rows = await src.loadRows(sb, { sport: SPORT, stat: STAT, modelVersion: MODEL_VERSION, before: today });
  rows.sort((a, b) => (a.date < b.date ? -1 : a.date > b.date ? 1 : (a.id < b.id ? -1 : 1)));
  const audit = src.eraAudit(rows, MODEL_VERSION);
  const dates = [...new Set(rows.map((r) => r.date))].sort();

  // ── STEP 15 — SAMPLE SUFFICIENCY ───────────────────────────────────────
  const bandN = {};
  for (const [lo, hi] of [[0.50, 0.60], [0.60, 0.70], [0.70, 0.80]]) {
    bandN[`${lo.toFixed(2)}-${hi.toFixed(2)}`] = rows.filter((r) => r.p >= lo && r.p < hi).length;
  }
  console.log(JSON.stringify({ section: 'SOURCE', model_version: MODEL_VERSION, fit_as_of: today,
    rows: rows.length, dates: dates.length, first: dates[0], last: dates[dates.length - 1],
    era_audit: audit, in_support: rows.filter((r) => inSupport(r.p)).length,
    band_n: bandN, min_fit_rows: MIN_FIT }, null, 1));

  // ── STEPS 14/16/17 — WALK-FORWARD, current era only ────────────────────
  const folds = [];
  const mapAt = Object.fromEntries(PROBES.map((p) => [p, []]));
  for (let f = FOLDS; f >= 1; f--) {
    const endIdx = dates.length - (f - 1) * FOLD_DATES;
    const startIdx = endIdx - FOLD_DATES;
    if (startIdx <= 0) continue;
    const evalDates = dates.slice(startIdx, endIdx);
    const trainRows = rows.filter((r) => r.date < evalDates[0]);           // STRICTLY before
    const evalRows = rows.filter((r) => evalDates.includes(r.date) && inSupport(r.p));
    if (trainRows.length < MIN_FIT || evalRows.length < 30) {
      folds.push({ fold: FOLDS - f + 1, eval_dates: evalDates, train_n: trainRows.length,
        eval_n: evalRows.length, refused: 'insufficient' });
      continue;
    }
    const map = cal.fitIsotonic(trainRows, { minTotal: MIN_FIT });
    if (!map) { folds.push({ fold: FOLDS - f + 1, refused: 'fitter refused' }); continue; }
    const ys = evalRows.map((r) => r.won);
    const rawP = evalRows.map((r) => r.p);
    const srv = evalRows.map((r) => cal.applyIsotonic(map, r.p) ?? r.p);
    const ci = pairedCI(srv, rawP, ys);
    // leak check: no training row may be dated at or after the eval block
    const leak = trainRows.filter((r) => r.date >= evalDates[0]).length;
    for (const p of PROBES) { const v = cal.applyIsotonic(map, p); if (v != null) mapAt[p].push(v); }
    const bands = [[0.50, 0.60], [0.60, 0.70], [0.70, 0.80]].map(([lo, hi]) => {
      const sel = evalRows.map((r, i) => (r.p >= lo && r.p < hi ? i : -1)).filter((i) => i >= 0);
      const k = sel.reduce((s, i) => s + ys[i], 0);
      const w = wilson(k, sel.length);
      return { band: `${lo.toFixed(2)}-${hi.toFixed(2)}`, n: sel.length,
        mean_served: sel.length ? r3(sel.reduce((s, i) => s + srv[i], 0) / sel.length) : null,
        observed: sel.length ? r3(k / sel.length) : null,
        observed_ci95: w ? [r3(w[0]), r3(w[1])] : null,
        error: sel.length ? r3(sel.reduce((s, i) => s + srv[i], 0) / sel.length - k / sel.length) : null };
    });
    folds.push({ fold: FOLDS - f + 1, eval_dates: evalDates, train_n: trainRows.length,
      train_through: trainRows[trainRows.length - 1].date, eval_n: evalRows.length,
      future_rows_in_train: leak,
      brier_raw: r5(brier(rawP, ys)), brier_candidate: r5(brier(srv, ys)),
      logloss_raw: r5(logloss(rawP, ys)), logloss_candidate: r5(logloss(srv, ys)),
      ece_raw: r5(ece(rawP, ys)), ece_candidate: r5(ece(srv, ys)),
      delta_brier: r5(brier(srv, ys) - brier(rawP, ys)), ci95: [r5(ci[0]), r5(ci[1])],
      bands });
  }
  console.log(JSON.stringify({ section: 'WALK_FORWARD', folds }, null, 1));
  console.log(JSON.stringify({ section: 'MAPPING_STABILITY',
    probes: Object.fromEntries(PROBES.map((p) => [p, summ(mapAt[p])])) }, null, 1));

  // ── POOLED across folds, and POLICY A vs POLICY B on the same folds ────
  const pooled = { raw: [], cand: [], y: [] };
  for (let f = FOLDS; f >= 1; f--) {
    const endIdx = dates.length - (f - 1) * FOLD_DATES;
    const startIdx = endIdx - FOLD_DATES;
    if (startIdx <= 0) continue;
    const evalDates = dates.slice(startIdx, endIdx);
    const trainAll = rows.filter((r) => r.date < evalDates[0]);
    const evalRows = rows.filter((r) => evalDates.includes(r.date) && inSupport(r.p));
    if (trainAll.length < MIN_FIT || !evalRows.length) continue;
    const mB = cal.fitIsotonic(trainAll, { minTotal: MIN_FIT });                     // POLICY B
    const cutA = Math.floor(trainAll.length * 0.65);
    const mA = cal.fitIsotonic(trainAll.slice(0, cutA), { minTotal: MIN_FIT });      // POLICY A
    if (!mA || !mB) continue;
    for (const r of evalRows) {
      pooled.y.push(r.won); pooled.raw.push(r.p);
      pooled.cand.push({ A: cal.applyIsotonic(mA, r.p) ?? r.p, B: cal.applyIsotonic(mB, r.p) ?? r.p });
    }
  }
  const yy = pooled.y;
  const A = pooled.cand.map((c) => c.A); const B = pooled.cand.map((c) => c.B);
  const ciA = pairedCI(A, pooled.raw, yy); const ciB = pairedCI(B, pooled.raw, yy);
  const ciAB = pairedCI(A, B, yy);
  console.log(JSON.stringify({ section: 'POLICY_A_VS_B_POOLED_FOLDS', n: yy.length,
    brier_raw: r5(brier(pooled.raw, yy)),
    A_era_filtered_65_35: { brier: r5(brier(A, yy)), logloss: r5(logloss(A, yy)), ece: r5(ece(A, yy)),
      delta_vs_raw: r5(brier(A, yy) - brier(pooled.raw, yy)), ci95: [r5(ciA[0]), r5(ciA[1])] },
    B_all_current_era: { brier: r5(brier(B, yy)), logloss: r5(logloss(B, yy)), ece: r5(ece(B, yy)),
      delta_vs_raw: r5(brier(B, yy) - brier(pooled.raw, yy)), ci95: [r5(ciB[0]), r5(ciB[1])] },
    A_minus_B: { delta: r5(brier(A, yy) - brier(B, yy)), ci95: [r5(ciAB[0]), r5(ciAB[1])] },
  }, null, 1));
  process.exit(0);
})().catch((e) => { console.error(e); process.exit(1); });