/**
 * Builds the composite index SiteEvent_sessionId_timestamp_idx on the
 * SiteEvent table using CREATE INDEX CONCURRENTLY.
 *
 * Must connect via the non-pooler (direct) Neon URL because:
 *   - CREATE INDEX CONCURRENTLY cannot run inside a transaction
 *   - The pooler enforces statement_timeout that overrides SET
 *
 * Usage:
 *   DIRECT_URL="postgres://..." node scripts/build-sessionid-index.mjs
 *
 * Never hardcode credentials here. Supply DIRECT_URL from the shell only.
 */

import pkg from "pg";
const { Client } = pkg;

const INDEX_NAME = "SiteEvent_sessionId_timestamp_idx";

const directUrl = process.env.DIRECT_URL;
if (!directUrl) {
  console.error("[build-index] DIRECT_URL is not set. Aborting.");
  process.exit(1);
}

const client = new Client({ connectionString: directUrl });

async function run() {
  console.log("[build-index] Connecting via DIRECT_URL...");
  await client.connect();
  console.log("[build-index] Connected.");

  console.log("[build-index] SET statement_timeout = 0");
  await client.query("SET statement_timeout = 0;");

  console.log("[build-index] SET lock_timeout = 0");
  await client.query("SET lock_timeout = 0;");

  console.log(`[build-index] DROP INDEX IF EXISTS "${INDEX_NAME}"`);
  await client.query(`DROP INDEX IF EXISTS "${INDEX_NAME}";`);
  console.log("[build-index] Drop complete (or index did not exist).");

  console.log(`[build-index] CREATE INDEX CONCURRENTLY "${INDEX_NAME}" -- this may take several minutes on large tables`);
  await client.query(
    `CREATE INDEX CONCURRENTLY "${INDEX_NAME}" ON "public"."SiteEvent" ("sessionId", "timestamp");`,
  );
  console.log("[build-index] Index build complete.");

  const res = await client.query(
    `SELECT indisvalid
       FROM pg_index
       JOIN pg_class ON pg_class.oid = pg_index.indexrelid
      WHERE pg_class.relname = $1;`,
    [INDEX_NAME],
  );

  if (res.rows.length === 0) {
    console.error("[build-index] Index not found after creation -- something went wrong.");
    process.exit(1);
  }

  const { indisvalid } = res.rows[0];
  if (indisvalid) {
    console.log("[build-index] indisvalid = true -- index is VALID and ready.");
  } else {
    console.error("[build-index] indisvalid = false -- index is INVALID. Manual cleanup required.");
    process.exit(1);
  }
}

run()
  .catch((err) => {
    console.error("[build-index] Fatal error:", err.message);
    process.exit(1);
  })
  .finally(() => {
    client.end().catch(() => {});
  });