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

/**
 * backfill-context — WERE WE WAITING, OR UNDER-QUERYING?
 *
 * The platoon test ran on 452 rows against 1,266 clean settled hits rows in the
 * ledger, so "48 short of the gate" was never a statement about how much data
 * exists. It was a statement about how much the JOIN survived — and the join was
 * losing rows to inputs we simply had not fetched for every player.
 *
 * This backfills the inputs (pure sample, zero waiting) and reports exactly
 * where each row is lost, so the next "we need more data" claim is a measured
 * one rather than an inherited one.
 *
 * ── THE ONE HONEST CAVEAT, STATED UP FRONT ───────────────────────────────
 * Platoon splits from statsapi are SEASON-TO-DATE as of the moment they are
 * fetched. Applying today's split to a 2026-07-15 game means the split contains
 * that game. For a ~400-PA season line one game is roughly a quarter of one
 * percent, so the contamination is small — but it is real, it runs in the
 * flattering direction, and it is why this is labelled a reconstruction rather
 * than a clean point-in-time backtest.
 *
 *   SUPABASE_URL=... node scripts/backfill-context.js
 */

require('dotenv').config();
const { createClient } = require('@supabase/supabase-js');
const ctx = require('../src/services/lineupContextService');
const mlb = require('../src/services/adapters/mlbStatsAdapter');
const { knownNumber } = require('../src/utils/known');
const { paginate } = require('../src/utils/safePaginate');
const { uniqueKeyFor } = require('../src/utils/tableKeys');

const SB_URL = process.env.SUPABASE_URL;
const SB_KEY = process.env.SUPABASE_SERVICE_ROLE_KEY || process.env.SUPABASE_SERVICE_KEY;
const SEASON = Number(process.env.BF_SEASON || 2026);
const PAGE = 1000;

// ── THE SAFE WALK (Fix A2/A2b) ────────────────────────────────────────────
// This script used to walk pages with `.range()` and NO ORDER BY. Measured on
// production, that returned the correct row COUNT and the wrong ROWS: up to
// 33.6% of a read came back twice while an equal share never came back at all,
// so `rows.length` looked perfect while a fifth of the sample was missing.
//
// `pageSafe` routes every read through `src/utils/safePaginate`: a stable ORDER
// BY on the table's real UNIQUE key — single OR composite, looked up from
// `src/utils/tableKeys` rather than assumed — a runtime tuple-uniqueness check,
// and a THROWN error instead of a silent stop. The old unordered helper is gone
// rather than left beside it, because a dead broken helper is an invitation.
async function pageSafe(sb, table, select, apply, key = uniqueKeyFor(table)) {
  return paginate(() => apply(sb.from(table).select(select)),
    { key, pageSize: PAGE, label: `${table}` });
}

/** THE MEASURED READS — main() and the harness call the same functions. */
const READS = {
  ledger: (sb) => pageSafe(sb, 'ledger_entries', 'id, player_key, player_name, stat, outcome, quarantine_reason',
    (q) => q.eq('sport', 'mlb').is('user_id', null).in('stat', ['hits', 'total_bases'])
      .in('outcome', ['hit', 'miss'])),
  platoonHeld: (sb) => pageSafe(sb, 'platoon_splits', 'as_of_date, sport, season, player_key',
    (q) => q.eq('sport', 'mlb')),
};

async function main() {
  if (!SB_URL || !SB_KEY) throw new Error('SUPABASE_URL / service key required');
  const sb = createClient(SB_URL, SB_KEY, { auth: { persistSession: false } });

  // Every hitter who appears on a CLEAN settled row — the true denominator.
  const led = await pageSafe(sb, 'ledger_entries', 'id, player_key, player_name, stat, outcome, quarantine_reason',
    (q) => q.eq('sport', 'mlb').is('user_id', null).in('stat', ['hits', 'total_bases'])
      .in('outcome', ['hit', 'miss']));
  const need = new Map();
  for (const r of led) {
    if ((r.quarantine_reason || '').startsWith('nontakeable_book')) continue;
    if (!need.has(r.player_key)) need.set(r.player_key, r.player_name);
  }

  const have = new Set((await pageSafe(sb, 'platoon_splits', 'as_of_date, sport, season, player_key', (q) => q.eq('sport', 'mlb')))
    .map((r) => r.player_key));
  const missing = [...need.entries()].filter(([k]) => !have.has(k));

  console.error(`[backfill] hitters on clean settled rows: ${need.size}; splits already held: ${have.size}; to fetch: ${missing.length}`);

  const asOf = ctx.dateET();
  const rows = [];
  let unresolved = 0;
  for (const [key, name] of missing) {
    let found = null;
    try { found = await mlb.searchPlayer(name); } catch { found = null; }
    if (!found || !found.id) { unresolved += 1; continue; }
    const sp = await ctx.fetchPlatoonSplits(found.id, SEASON, {});
    if (!sp) continue;                       // absent, never a symmetric guess
    rows.push({ player_key: key, player_name: name, source_id: found.id, ...sp });
  }

  let written = 0;
  for (let i = 0; i < rows.length; i += 200) {
    const batch = rows.slice(i, i + 200).map((r) => ({ ...r, sport: 'mlb', season: SEASON, as_of_date: asOf }));
    const { error } = await sb.from('platoon_splits')
      .upsert(batch, { onConflict: 'as_of_date,sport,season,player_key' });
    if (!error) written += batch.length;
    else console.error('[backfill] write failed:', error.message);
  }

  console.log(JSON.stringify({
    hitters_on_clean_settled_rows: need.size,
    splits_held_before: have.size,
    attempted: missing.length,
    unresolved_by_name: unresolved,
    no_splits_available: missing.length - unresolved - rows.length,
    written,
    caveat: 'season-to-date splits applied to past games contain those games — small (~0.25% of a 400-PA line) but real and flattering',
  }, null, 2));
  process.exit(0);
}

if (require.main === module) {
  main().catch((e) => { console.error(e); process.exit(1); });
}

// Exported so the read-integrity harness measures THE REAL FUNCTION.
module.exports = { READS: (typeof READS !== 'undefined' ? READS : undefined), READS_LEDGER: (typeof READS_LEDGER !== 'undefined' ? READS_LEDGER : undefined) };