import { pool } from '../../src/db';
import { assertSchemaPresent, migrate, resetDb, testPool, closeDb } from './setup/testDb';

/**
 * The diagnostic for #154, exercised against a database that has actually lost
 * its schema.
 *
 * The failure this guards is not hypothetical and not cheap: the integration run
 * lost its schema partway through, and it presented as 36 assertion errors about
 * categories, price filters and favourite notifications. The real message —
 * `relation "items" does not exist` — was further down the same log.
 *
 * This suite destroys and rebuilds the schema, so it restores in afterAll and
 * `migrate()` is what puts it back: dropping the schema takes `pgmigrations`
 * with it, so node-pg-migrate re-runs everything rather than believing it has
 * already done so.
 */
async function dropEverything(): Promise<void> {
  await testPool.query('DROP SCHEMA public CASCADE; CREATE SCHEMA public;');
}

afterAll(async () => {
  // Put it back before anything else in the run touches it. Ordering matters:
  // jest runs these in band, so a suite after this one would otherwise find
  // nothing at all.
  await migrate();
  await pool.end();
  await closeDb();
});

describe('when the database loses its schema', () => {
  it('assertSchemaPresent says so, rather than letting the suite guess', async () => {
    await dropEverything();

    await expect(assertSchemaPresent('in a test')).rejects.toThrow(/has no schema \(in a test\)/);

    await migrate();
  });

  it('names the tables that are missing', async () => {
    await dropEverything();

    // The count and a few names, not the whole list: the point is that a reader
    // can tell at a glance this is a missing schema rather than a logic bug.
    await expect(assertSchemaPresent('in a test')).rejects.toThrow(/Missing 20 of 20 tables/);
    await expect(assertSchemaPresent('in a test')).rejects.toThrow(/items/);

    await migrate();
  });

  it('points at the cause rather than leaving it to be rediscovered', async () => {
    await dropEverything();

    await expect(assertSchemaPresent('in a test')).rejects.toThrow(/TRUNCATE does not/);
    await expect(assertSchemaPresent('in a test')).rejects.toThrow(/#154/);

    await migrate();
  });

  // The path a real run takes: resetDb's TRUNCATE is what fails first, and it
  // has to turn that into the schema message rather than passing on a bare
  // "relation does not exist".
  it('resetDb turns a failed truncate into the schema message', async () => {
    await dropEverything();

    await expect(resetDb()).rejects.toThrow(/has no schema \(while resetting between tests\)/);

    await migrate();
  });

  // And it must not swallow unrelated failures behind a schema message.
  it('says nothing about the schema when the schema is fine', async () => {
    await expect(assertSchemaPresent('in a test')).resolves.toBeUndefined();
    await expect(resetDb()).resolves.toBeUndefined();
  });
});