#!/usr/bin/env node
'use strict';

/**
 * PHASE 1 — derive a COHERENT LODO test, blind to reversals.
 *
 * ── THE DEFECT BEING FIXED ───────────────────────────────────────────────
 * The gate at 1f40014 paired a 1-SE per-drop informativeness bar with a
 * zero-reversal decision rule. Those two are incoherent. At exactly 1 SE, a
 * genuinely STABLE stat's drop reverses with probability Phi(-1) = 0.159, so on
 * four informative drops the chance of at least one reversal is
 * 1 - 0.841^4 = 0.50. The rule failed stable stats half the time by construction.
 *
 * And n* was pooled across four stats whose signed effects differ several-fold,
 * so "informative" meant different things for different stats while being
 * treated as one number.
 *
 * ── THE FIX ──────────────────────────────────────────────────────────────
 * The two halves have to be chosen together:
 *
 *   informative bar   n*_k = k^2 * (sigma_row / |g|)^2      PER STAT
 *   decision rule     FAIL iff reversals > c, where under stability
 *                     R ~ Binomial(D, Phi(-k)) and c is the smallest cutoff
 *                     with P(R > c) <= 0.05
 *
 * `g` is the mean SIGNED per-row improvement — the quantity whose sign a
 * reversal flips. Not a mean-absolute, and not pooled: a reversal is a claim
 * about THIS stat's effect changing sign.
 *
 * THIS SCRIPT PRINTS NO REVERSAL AND NO VERDICT. It is blind by construction and
 * must run, and its constants be committed, before any stat is re-read.
 *
 *   SUPABASE_URL=... node scripts/derive-lodo-test.js
 */

require('dotenv').config();
const fs = require('fs');
const path = require('path');
const { createClient } = require('@supabase/supabase-js');
const cal = require('../src/services/model/calibration');
const guards = require('../src/services/model/calibrationGuards');
const { knownNumber } = require('../src/utils/known');

const BOX = path.join(process.cwd(), '.seq-cache', 'batting-lines.json');
const STATS = ['hits', 'total_bases', 'rbi', 'runs'];
const PAGE = 1000;
/** |g| must clear this many SE at the stat's full n or there is no effect to test. */
const EFFECT_Z = 1.96;
/** Target false-positive rate for the whole per-stat test. */
const TARGET_FP = 0.05;

const FIELD = { hits: (b) => b.hits, total_bases: (b) => b.totalBases, rbi: (b) => b.rbi, runs: (b) => b.runs };
const mean = (xs) => (xs.length ? xs.reduce((a, b) => a + b, 0) / xs.length : null);

/** Standard normal CDF (Abramowitz–Stegun 7.1.26 via erf). */
function normCdf(z) {
  const t = 1 / (1 + 0.2316419 * Math.abs(z));
  const d = 0.3989422804014327 * Math.exp(-z * z / 2);
  const p = d * t * (0.319381530 + t * (-0.356563782 + t * (1.781477937 + t * (-1.821255978 + t * 1.330274429))));
  return z >= 0 ? 1 - p : p;
}

const binomPmf = (n, k, p) => {
  let logC = 0;
  for (let i = 0; i < k; i += 1) logC += Math.log(n - i) - Math.log(i + 1);
  return Math.exp(logC + k * Math.log(p) + (n - k) * Math.log(1 - p));
};
/** P(R > c) for R ~ Binomial(n, p). */
const binomTail = (n, c, p) => {
  let s = 0;
  for (let k = c + 1; k <= n; k += 1) s += binomPmf(n, k, p);
  return s;
};
/** Smallest cutoff c with P(R > c) <= target. */
function cutoffFor(D, p, target) {
  for (let c = 0; c <= D; c += 1) if (binomTail(D, c, p) <= target) return { cutoff: c, fp: binomTail(D, c, p) };
  return { cutoff: D, fp: 0 };
}

async function page(sb, t, s, f) {
  const o = [];
  for (let i = 0; ; i += PAGE) {
    const { data, error } = await f(sb.from(t).select(s)).order('id', { ascending: true }).range(i, i + PAGE - 1);
    if (error) throw error;
    if (!data.length) break;
    o.push(...data);
    if (data.length < PAGE) break;
  }
  return o;
}
const isPreGame = (c, g) => {
  const et = new Date(new Date(c).getTime() - 4 * 3600 * 1000);
  const d = et.toISOString().slice(0, 10);
  return d < g || (d === g && et.getUTCHours() < 19);
};

(async () => {
  const sb = createClient(process.env.SUPABASE_URL,
    process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.SUPABASE_SERVICE_KEY, { auth: { persistSession: false } });
  const lines = JSON.parse(fs.readFileSync(BOX, 'utf8')).lines;

  const snaps = await page(sb, 'model_snapshots',
    'id, game_date, captured_at, stat, player_key, line, side, p_win, refused',
    (q) => q.eq('sport', 'mlb').in('stat', STATS));

  const picked = new Map();
  for (const r of snaps) {
    if (!isPreGame(r.captured_at, r.game_date) || r.refused || knownNumber(r.p_win) === null) continue;
    const k = [r.game_date, r.stat, r.player_key, r.line].join('|');
    const prev = picked.get(k);
    if (!prev || knownNumber(r.p_win) > knownNumber(prev.p_win)) picked.set(k, r);
  }
  guards.assertPickedSideDedup([...picked.values()].map((r) => ({
    propKey: [r.game_date, r.stat, r.player_key, r.line].join('|'), side: r.side, p: knownNumber(r.p_win),
  })));

  const perStat = {};
  const dateSizes = {};

  for (const stat of STATS) {
    const rows = [];
    for (const r of picked.values()) {
      if (r.stat !== stat) continue;
      const b = lines[`${r.game_date}|${r.player_key}`];
      const L = knownNumber(r.line);
      if (!b || L === null || !r.side) continue;
      const v = knownNumber(FIELD[stat](b));
      if (v === null) continue;
      const over = v > L;
      rows.push({ date: r.game_date, p: knownNumber(r.p_win), won: (String(r.side).toLowerCase() === 'under' ? !over : over) ? 1 : 0 });
    }
    const map = cal.fitIsotonic(rows.map((r) => ({ p: r.p, won: r.won })));
    if (!map) { perStat[stat] = { n: rows.length, fittable: false }; continue; }

    const d = [];
    for (const r of rows) {
      const pc = cal.applyIsotonic(map, r.p);
      if (knownNumber(pc) === null) continue;
      d.push((pc - r.won) ** 2 - (r.p - r.won) ** 2);
    }
    const g = mean(d);
    const sigma = Math.sqrt(d.reduce((s, x) => s + (x - g) ** 2, 0) / (d.length - 1));
    const seFull = sigma / Math.sqrt(d.length);

    // Date sizes are sample STRUCTURE, not outcomes — safe to read here.
    const sizes = new Map();
    for (const r of rows) sizes.set(r.date, (sizes.get(r.date) || 0) + 1);
    dateSizes[stat] = [...sizes.values()].sort((a, b) => b - a);

    perStat[stat] = {
      n: d.length,
      g_signed: round5(g),
      sigma_row: round5(sigma),
      se_full: round5(seFull),
      effect_z_at_full_n: round3(Math.abs(g) / seFull),
      improves: g < 0,
      no_effect: Math.abs(g) / seFull < EFFECT_Z,
      fittable: true,
    };
  }

  // ── Choose k jointly. Blind: uses only (g, sigma) and date SIZES. ──
  const kTable = [];
  for (const k of [1.0, 1.25, 1.5, 1.75, 2.0]) {
    const pNoise = normCdf(-k);
    const row = { k, per_drop_noise_prob: round4(pNoise), stats: {} };
    for (const stat of STATS) {
      const ps = perStat[stat];
      if (!ps || !ps.fittable) continue;
      const nStar = Math.ceil(k * k * (ps.sigma_row / Math.abs(ps.g_signed)) ** 2);
      const D = (dateSizes[stat] || []).filter((n) => n >= nStar).length;
      const { cutoff, fp } = D > 0 ? cutoffFor(D, pNoise, TARGET_FP) : { cutoff: null, fp: null };
      // FN at a stated alternative: date-to-date SD of the effect equals |g|.
      const pAlt = D > 0 ? normCdf(-Math.abs(ps.g_signed) / Math.sqrt(ps.g_signed ** 2 + (ps.sigma_row ** 2) / nStar)) : null;
      const fn = D > 0 && cutoff !== null ? 1 - binomTail(D, cutoff, pAlt) : null;
      row.stats[stat] = {
        n_star: nStar, informative_drops: D, cutoff, fp: fp === null ? null : round4(fp),
        fn_at_tau_equals_g: fn === null ? null : round4(fn),
      };
    }
    kTable.push(row);
  }

  console.log(JSON.stringify({
    phase: 'PHASE 1 — coherent LODO test derivation, BLIND',
    defect_being_fixed: 'a 1-SE informative bar with a zero-reversal rule: P(>=1 reversal | stable, 4 drops) = 0.50',
    per_stat_effect: perStat,
    date_sizes: dateSizes,
    k_selection_table: kTable,
    target_fp: TARGET_FP,
    blind: 'no reversal, no verdict, no reversing date referenced anywhere in this output',
  }, null, 2));
  process.exit(0);
})().catch((e) => { console.error(e); process.exit(1); });

const round5 = (v) => (v == null || !Number.isFinite(v) ? null : Math.round(v * 100000) / 100000);
const round4 = (v) => (v == null || !Number.isFinite(v) ? null : Math.round(v * 10000) / 10000);
const round3 = (v) => (v == null || !Number.isFinite(v) ? null : Math.round(v * 1000) / 1000);