'use strict';

/**
 * DRIFT CHECK — compare the committed schema contract against a LIVE database.
 *
 * The unit guard proves the retention writer stays inside the contract. This
 * proves the CONTRACT still describes reality. Both are needed: a correct
 * writer against a stale contract is the same failure wearing a different hat.
 *
 *   SUPABASE_URL=... SUPABASE_SERVICE_KEY=... node scripts/verify-schema-contract.js
 *
 * Exit 0 when the live table is a superset of the contract (safe: every column
 * the writer may emit exists). Exit 1 when a contract column is MISSING live —
 * that is the condition that breaks retention.
 */

const fs = require('fs');
const path = require('path');
const { createClient } = require('@supabase/supabase-js');

const TABLE = process.env.SCHEMA_TABLE || 'model_snapshots';

async function main() {
  const contract = JSON.parse(fs.readFileSync(
    path.join(__dirname, '..', 'supabase', 'schema', `${TABLE}.columns.json`), 'utf8'));
  const url = process.env.SUPABASE_URL;
  const key = process.env.SUPABASE_SERVICE_KEY || process.env.SUPABASE_SERVICE_ROLE_KEY;
  if (!url || !key) throw new Error('SUPABASE_URL + service key required');
  const sb = createClient(url, key, { auth: { persistSession: false } });

  // One row is enough to learn the live column set from the response shape.
  const { data, error } = await sb.from(TABLE).select('*').limit(1);
  if (error) throw new Error(`live read failed: ${error.message}`);
  if (!data || data.length === 0) throw new Error(`${TABLE} is empty — cannot infer live columns`);

  const live = new Set(Object.keys(data[0]));
  const missing = contract.columns.filter((c) => !live.has(c));
  const extra = [...live].filter((c) => !contract.columns.includes(c)).sort();

  console.log(`contract columns : ${contract.columns.length}`);
  console.log(`live columns     : ${live.size}`);
  console.log(`live-only (informational, safe): ${extra.length ? extra.join(', ') : 'none'}`);
  console.log(`MISSING LIVE (breaks retention): ${missing.length ? missing.join(', ') : 'none'}`);
  process.exit(missing.length ? 1 : 0);
}

if (require.main === module) {
  main().catch((e) => { console.error('FAILED:', e.message); process.exit(1); });
}