// Prints one word: is this database already carrying the app's schema?
//
//   ready        the baseline tables exist; migrations can be applied on top
//   empty        nothing here yet
//   unreachable  could not connect or could not tell
//
// Used by docker-entrypoint.sh to decide whether it may migrate before the app
// starts. The schema has two layers — src/db/database.js creates the baseline
// with CREATE TABLE IF NOT EXISTS on first connect, and the migrations layer on
// top of it. Against an empty database the migrations fail, because the
// earliest of them alters a table only the baseline creates.
//
// Never exits non-zero: an answer of "unreachable" is for the caller to handle,
// and a database still opening its socket is not an error worth stopping on.
const { Client } = require('pg');

const client = new Client({ connectionString: process.env.DATABASE_URL });
client.connect()
  .then(() => client.query("select to_regclass('public.users') is not null as ready"))
  .then((result) => {
    process.stdout.write(result.rows[0] && result.rows[0].ready ? 'ready' : 'empty');
    return client.end();
  })
  .catch(() => {
    process.stdout.write('unreachable');
    try { client.end(); } catch (e) { /* already down */ }
  });