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';

// Shared db across the file (see test.mongoledger.ts for the rationale).
// Each test uses a unique ledgerName for isolation.
let db: smartdata.SmartdataDb;
let cleanup: () => Promise<void>;

async function setLedgerVersion(ledgerName: string, currentVersion: string): Promise<void> {
  await db.mongoDb.collection('SmartdataEasyStore').updateOne(
    { nameId: `smartmigration:${ledgerName}` },
    {
      $set: {
        nameId: `smartmigration:${ledgerName}`,
        data: {
          currentVersion,
          steps: {},
          lock: { holder: null, acquiredAt: null, expiresAt: null },
          checkpoints: {},
        },
      },
    },
    { upsert: true },
  );
}

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

tap.test('run: applies all steps from scratch', async () => {
  const m = new SmartMigration({ targetVersion: '2.0.0', db, ledgerName: 'scratch' });
  const log: string[] = [];
  m
    .step('a').from('1.0.0').to('1.1.0').up(async () => { log.push('a'); })
    .step('b').from('1.1.0').to('1.5.0').up(async () => { log.push('b'); })
    .step('c').from('1.5.0').to('2.0.0').up(async () => { log.push('c'); });

  const r = await m.run();
  expect(r.stepsApplied).toHaveLength(3);
  expect(log).toEqual(['a', 'b', 'c']);
  expect(r.currentVersionAfter).toEqual('2.0.0');
  expect(r.wasUpToDate).toBeFalse();
  expect(r.targetVersion).toEqual('2.0.0');
});

tap.test('run: second run is a no-op', async () => {
  const m = new SmartMigration({ targetVersion: '2.0.0', db, ledgerName: 'idempotent' });
  const log: string[] = [];
  m
    .step('a').from('1.0.0').to('1.1.0').up(async () => { log.push('a'); })
    .step('b').from('1.1.0').to('2.0.0').up(async () => { log.push('b'); });

  const r1 = await m.run();
  expect(r1.stepsApplied).toHaveLength(2);
  expect(log).toEqual(['a', 'b']);

  // Re-run with a freshly-constructed runner using the same ledger.
  const m2 = new SmartMigration({ targetVersion: '2.0.0', db, ledgerName: 'idempotent' });
  m2
    .step('a').from('1.0.0').to('1.1.0').up(async () => { log.push('a-again'); })
    .step('b').from('1.1.0').to('2.0.0').up(async () => { log.push('b-again'); });
  const r2 = await m2.run();
  expect(r2.wasUpToDate).toBeTrue();
  expect(r2.stepsApplied).toHaveLength(0);
  expect(log).toEqual(['a', 'b']); // no new entries
});

tap.test('run: failing step throws and persists failure', async () => {
  const m = new SmartMigration({ targetVersion: '2.0.0', db, ledgerName: 'failure' });
  let aCalled = false;
  m
    .step('a').from('1.0.0').to('1.1.0').up(async () => { aCalled = true; })
    .step('b').from('1.1.0').to('2.0.0').up(async () => { throw new Error('boom'); });

  let caught: SmartMigrationError | undefined;
  try {
    await m.run();
  } catch (err) {
    caught = err as SmartMigrationError;
  }
  expect(caught).toBeInstanceOf(SmartMigrationError);
  expect(caught!.code).toEqual('STEP_FAILED');
  expect(aCalled).toBeTrue();

  // Ledger should be at 1.1.0 (after step a, before failed step b).
  const current = await m.getCurrentVersion();
  expect(current).toEqual('1.1.0');
});

tap.test('run: ctx exposes db, mongo, and step metadata', async () => {
  const m = new SmartMigration({ targetVersion: '1.1.0', db, ledgerName: 'ctx' });
  let observed: { hasDb: boolean; hasMongo: boolean; stepId: string; from: string; to: string } | null = null;
  m.step('check-ctx').from('1.0.0').to('1.1.0').up(async (ctx) => {
    observed = {
      hasDb: !!ctx.db,
      hasMongo: !!ctx.mongo,
      stepId: ctx.step.id,
      from: ctx.step.fromVersion,
      to: ctx.step.toVersion,
    };
    // exercise raw mongo
    await ctx.mongo!.collection('users_ctx_test').insertOne({ name: 'alice' });
  });
  await m.run();
  expect(observed).not.toBeNull();
  expect(observed!.hasDb).toBeTrue();
  expect(observed!.hasMongo).toBeTrue();
  expect(observed!.stepId).toEqual('check-ctx');
  expect(observed!.from).toEqual('1.0.0');
  expect(observed!.to).toEqual('1.1.0');
  // verify the data the step wrote
  const found = await db.mongoDb.collection('users_ctx_test').findOne({ name: 'alice' });
  expect(found).not.toBeNull();
});

tap.test('run: ctx.startSession works inside a step', async () => {
  const m = new SmartMigration({ targetVersion: '1.1.0', db, ledgerName: 'session' });
  let sessionWasUsed = false;
  m.step('with-session').from('1.0.0').to('1.1.0').up(async (ctx) => {
    const session = ctx.startSession();
    try {
      sessionWasUsed = !!session.id;
      await session.endSession();
    } catch (err) {
      await session.endSession();
      throw err;
    }
  });
  await m.run();
  expect(sessionWasUsed).toBeTrue();
});

tap.test('run: lock heartbeat prevents concurrent execution of a slow step', async () => {
  let activeSteps = 0;
  let maxActiveSteps = 0;
  let totalCalls = 0;

  const createRunner = () => {
    const m = new SmartMigration({
      targetVersion: '1.1.0',
      db,
      ledgerName: 'lock_heartbeat',
      lockTtlMs: 100,
      lockWaitMs: 1_500,
    });

    m.step('slow-step').from('1.0.0').to('1.1.0').up(async () => {
      totalCalls++;
      activeSteps++;
      maxActiveSteps = Math.max(maxActiveSteps, activeSteps);
      await new Promise((resolve) => setTimeout(resolve, 900));
      activeSteps--;
    });

    return m;
  };

  const firstRun = createRunner().run();
  await new Promise((resolve) => setTimeout(resolve, 20));
  const secondRun = createRunner().run();

  const [firstResult, secondResult] = await Promise.all([firstRun, secondRun]);
  expect(firstResult.stepsApplied).toHaveLength(1);
  expect(secondResult.wasUpToDate).toBeTrue();
  expect(totalCalls).toEqual(1);
  expect(maxActiveSteps).toEqual(1);
});

tap.test('run: strict target strategy rejects target beyond registered chain', async () => {
  await setLedgerVersion('strict_target_gap', '2.0.0');

  const m = new SmartMigration({ targetVersion: '3.0.0', db, ledgerName: 'strict_target_gap' });
  m.step('a').from('1.0.0').to('2.0.0').up(async () => {});

  let caught: SmartMigrationError | undefined;
  try {
    await m.run();
  } catch (err) {
    caught = err as SmartMigrationError;
  }

  expect(caught).toBeInstanceOf(SmartMigrationError);
  expect(caught!.code).toEqual('TARGET_NOT_REACHABLE');
});

tap.test('run: bridge target strategy stamps from past chain end to target', async () => {
  await setLedgerVersion('bridge_from_past_chain_end', '2.5.0');

  let realStepCalled = false;
  const m = new SmartMigration({
    targetVersion: '3.0.0',
    db,
    ledgerName: 'bridge_from_past_chain_end',
    targetVersionStrategy: 'bridge',
  });
  m.step('a').from('1.0.0').to('2.0.0').up(async () => { realStepCalled = true; });

  const r = await m.run();

  expect(realStepCalled).toBeFalse();
  expect(r.stepsApplied).toHaveLength(1);
  expect(r.stepsApplied[0].id).toEqual('smartmigration-auto-bridge-to-3.0.0');
  expect(r.stepsApplied[0].fromVersion).toEqual('2.0.0');
  expect(r.currentVersionAfter).toEqual('3.0.0');
  expect(await m.getCurrentVersion()).toEqual('3.0.0');
});

tap.test('run: bridge target strategy runs real migrations before bridge', async () => {
  await setLedgerVersion('bridge_after_real_steps', '1.0.0');

  const log: string[] = [];
  const m = new SmartMigration({
    targetVersion: '3.0.0',
    db,
    ledgerName: 'bridge_after_real_steps',
    targetVersionStrategy: 'bridge',
  });
  m.step('a').from('1.0.0').to('2.0.0').up(async () => { log.push('a'); });

  const r = await m.run();

  expect(log).toEqual(['a']);
  expect(r.stepsApplied.map((step) => step.id)).toEqual([
    'a',
    'smartmigration-auto-bridge-to-3.0.0',
  ]);
  expect(r.currentVersionAfter).toEqual('3.0.0');
});

tap.test('plan: bridge target strategy is read-only', async () => {
  await setLedgerVersion('bridge_plan_readonly', '2.5.0');

  const m = new SmartMigration({
    targetVersion: '3.0.0',
    db,
    ledgerName: 'bridge_plan_readonly',
    targetVersionStrategy: 'bridge',
  });
  m.step('a').from('1.0.0').to('2.0.0').up(async () => {});

  const r = await m.plan();

  expect(r.stepsSkipped).toHaveLength(1);
  expect(r.stepsSkipped[0].id).toEqual('smartmigration-auto-bridge-to-3.0.0');
  expect(r.currentVersionAfter).toEqual('3.0.0');
  expect(await m.getCurrentVersion()).toEqual('2.5.0');
});

tap.test('run: future real migration applies after a bridged version stamp', async () => {
  await setLedgerVersion('bridge_future_migration', '2.5.0');

  const bridgeRunner = new SmartMigration({
    targetVersion: '3.0.0',
    db,
    ledgerName: 'bridge_future_migration',
    targetVersionStrategy: 'bridge',
  });
  bridgeRunner.step('a').from('1.0.0').to('2.0.0').up(async () => {});
  await bridgeRunner.run();

  let futureStepCalled = false;
  const futureRunner = new SmartMigration({
    targetVersion: '4.0.0',
    db,
    ledgerName: 'bridge_future_migration',
    targetVersionStrategy: 'bridge',
  });
  futureRunner
    .step('a').from('1.0.0').to('2.0.0').up(async () => {})
    .step('future').from('2.0.0').to('4.0.0').up(async () => { futureStepCalled = true; });

  const r = await futureRunner.run();

  expect(futureStepCalled).toBeTrue();
  expect(r.stepsApplied.map((step) => step.id)).toEqual(['future']);
  expect(r.currentVersionAfter).toEqual('4.0.0');
});

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

export default tap.start();