'use strict';

/**
 * Regenerate supabase/schema/model_snapshots.columns.json from the MIGRATION
 * CHAIN, by applying every committed migration to a disposable postgres and
 * reading information_schema.
 *
 * The contract must be DERIVED, never hand-maintained: a hand-written list is
 * a second opinion about the schema, and a second opinion is exactly what let
 * `published_side` reach production. Deriving it from the same migrations the
 * release verification applies means the list cannot drift from the release.
 *
 *   docker run -d --name schema-gen -e POSTGRES_PASSWORD=test -e POSTGRES_DB=v postgres:15-alpine
 *   node scripts/generate-schema-contract.js schema-gen
 *
 * Drift against a LIVE database is a separate question — see
 * scripts/verify-schema-contract.js.
 */

const { execFileSync } = require('child_process');
const fs = require('fs');
const path = require('path');

const CONTAINER = process.argv[2];
const TABLE = process.env.SCHEMA_TABLE || 'model_snapshots';
const OUT = path.join(__dirname, '..', 'supabase', 'schema', `${TABLE}.columns.json`);

function psql(sql) {
  return execFileSync('docker', ['exec', CONTAINER, 'psql', '-U', 'postgres', '-d', 'v', '-tAc', sql],
    { encoding: 'utf8' }).trim();
}

function main() {
  if (!CONTAINER) throw new Error('usage: node scripts/generate-schema-contract.js <container>');
  const cols = psql(
    `select string_agg(column_name, ',' order by column_name)`
    + ` from information_schema.columns`
    + ` where table_schema='public' and table_name='${TABLE}'`
    + `   and is_generated='NEVER' and identity_generation is null;`,
  ).split(',').filter(Boolean);
  if (cols.length === 0) throw new Error(`no columns found for ${TABLE} — was the migration chain applied?`);

  const prev = fs.existsSync(OUT) ? JSON.parse(fs.readFileSync(OUT, 'utf8')) : {};
  const doc = {
    ...prev,
    table: TABLE,
    generated_by: 'scripts/generate-schema-contract.js',
    derived_from: 'supabase/migrations/*.sql applied in order to a disposable postgres:15-alpine',
    column_count: cols.length,
    columns: cols,
  };
  fs.writeFileSync(OUT, `${JSON.stringify(doc, null, 2)}\n`);
  console.log(`wrote ${OUT} — ${cols.length} columns`);
}

if (require.main === module) main();