import { tap, expect } from '@git.zone/tstest/tapbundle';
import { makeTestDb } from './helpers/services.js';
import type * as smartdata from '@push.rocks/smartdata';
import { SmartMigration, SmartMigrationError } from '../ts/index.js';

let db: smartdata.SmartdataDb;
let cleanup: () => Promise<void>;

tap.test('setup: connect shared db', async () => {
  const r = await makeTestDb('checkpoint');
  db = r.db;
  cleanup = r.cleanup;
});

tap.test('checkpoint: resumable step writes and re-reads progress across runs', async () => {
  // First runner: simulate a crash after writing the first half of the work.
  const m1 = new SmartMigration({ targetVersion: '1.1.0', db, ledgerName: 'resume' });
  let crashed = false;
  m1.step('big-job').from('1.0.0').to('1.1.0').resumable().up(async (ctx) => {
    const seen = (await ctx.checkpoint!.read<number>('processed')) ?? 0;
    // Pretend we processed items 0..4 and then crash.
    for (let i = seen; i < 5; i++) {
      await ctx.checkpoint!.write('processed', i + 1);
    }
    crashed = true;
    throw new Error('simulated crash mid-step');
  });

  let caught: SmartMigrationError | undefined;
  try {
    await m1.run();
  } catch (err) {
    caught = err as SmartMigrationError;
  }
  expect(caught).toBeInstanceOf(SmartMigrationError);
  expect(crashed).toBeTrue();

  // Second runner: should see the checkpoint and resume from item 5.
  const m2 = new SmartMigration({ targetVersion: '1.1.0', db, ledgerName: 'resume' });
  let resumedFrom: number | undefined;
  let finalCount: number | undefined;
  m2.step('big-job').from('1.0.0').to('1.1.0').resumable().up(async (ctx) => {
    resumedFrom = (await ctx.checkpoint!.read<number>('processed')) ?? 0;
    // Process items 5..9.
    let n = resumedFrom;
    while (n < 10) {
      n++;
      await ctx.checkpoint!.write('processed', n);
    }
    finalCount = n;
  });
  const r = await m2.run();
  expect(resumedFrom).toEqual(5);
  expect(finalCount).toEqual(10);
  expect(r.currentVersionAfter).toEqual('1.1.0');
});

tap.test('checkpoint: ctx.checkpoint is undefined for non-resumable steps', async () => {
  const m = new SmartMigration({ targetVersion: '1.1.0', db, ledgerName: 'noresume' });
  let observed: boolean | undefined;
  m.step('plain').from('1.0.0').to('1.1.0').up(async (ctx) => {
    observed = ctx.checkpoint === undefined;
  });
  await m.run();
  expect(observed).toBeTrue();
});

tap.test('cleanup: close shared db', async () => {
  await cleanup();
});

export default tap.start();