import { expect, tap } from '@git.zone/tstest/tapbundle';
import * as smartdb from '../ts/index.js';
import { MongoClient, Db } from 'mongodb';
import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

let tmpDir: string;
let server: smartdb.SmartdbServer;
let client: MongoClient;
let db: Db;

function makeTmpDir(): string {
  return fs.mkdtempSync(path.join(os.tmpdir(), 'smartdb-compact-test-'));
}

function cleanTmpDir(dir: string): void {
  if (fs.existsSync(dir)) {
    fs.rmSync(dir, { recursive: true, force: true });
  }
}

function getDataFileSize(storagePath: string, dbName: string, collName: string): number {
  const dataPath = path.join(storagePath, dbName, collName, 'data.rdb');
  if (!fs.existsSync(dataPath)) return 0;
  return fs.statSync(dataPath).size;
}

// ============================================================================
// Compaction: Setup
// ============================================================================

tap.test('compaction: start server with file storage', async () => {
  tmpDir = makeTmpDir();
  server = new smartdb.SmartdbServer({
    socketPath: path.join(os.tmpdir(), `smartdb-compact-${Date.now()}-${Math.random().toString(36).slice(2)}.sock`),
    storage: 'file',
    storagePath: tmpDir,
  });
  await server.start();

  client = new MongoClient(server.getConnectionUri(), {
    directConnection: true,
    serverSelectionTimeoutMS: 5000,
  });
  await client.connect();
  db = client.db('compactdb');
});

// ============================================================================
// Compaction: Updates grow the data file
// ============================================================================

tap.test('compaction: repeated updates grow the data file', async () => {
  const coll = db.collection('growing');

  // Insert a document
  await coll.insertOne({ key: 'target', counter: 0, payload: 'x'.repeat(200) });

  const sizeAfterInsert = getDataFileSize(tmpDir, 'compactdb', 'growing');
  expect(sizeAfterInsert).toBeGreaterThan(0);

  // Update the same document 50 times — each update appends a new record
  for (let i = 1; i <= 50; i++) {
    await coll.updateOne(
      { key: 'target' },
      { $set: { counter: i, payload: 'y'.repeat(200) } }
    );
  }

  const sizeAfterUpdates = getDataFileSize(tmpDir, 'compactdb', 'growing');
  // Compaction may have run during updates, so we can't assert the file is
  // much larger. What matters is the data is correct.

  // The collection still has just 1 document
  const count = await coll.countDocuments();
  expect(count).toEqual(1);

  const doc = await coll.findOne({ key: 'target' });
  expect(doc!.counter).toEqual(50);
});

// ============================================================================
// Compaction: Deletes create tombstones
// ============================================================================

tap.test('compaction: insert-then-delete creates dead space', async () => {
  const coll = db.collection('tombstones');

  // Insert 100 documents
  const docs = [];
  for (let i = 0; i < 100; i++) {
    docs.push({ idx: i, data: 'delete-me-' + 'z'.repeat(100) });
  }
  await coll.insertMany(docs);

  const sizeAfterInsert = getDataFileSize(tmpDir, 'compactdb', 'tombstones');

  // Delete all 100
  await coll.deleteMany({});

  const sizeAfterDelete = getDataFileSize(tmpDir, 'compactdb', 'tombstones');
  // File may have been compacted during deletes (dead > 50% threshold),
  // but the operation itself should succeed regardless of file size.
  // After deleting all docs, the file might be very small (just header + compacted).

  // But count is 0
  const count = await coll.countDocuments();
  expect(count).toEqual(0);
});

// ============================================================================
// Compaction: Data integrity after compaction trigger
// ============================================================================

tap.test('compaction: data file shrinks after heavy updates trigger compaction', async () => {
  const coll = db.collection('shrinktest');

  // Insert 10 documents with large payloads
  const docs = [];
  for (let i = 0; i < 10; i++) {
    docs.push({ idx: i, data: 'a'.repeat(500) });
  }
  await coll.insertMany(docs);

  const sizeAfterInsert = getDataFileSize(tmpDir, 'compactdb', 'shrinktest');

  // Update each document 20 times (creates 200 dead records vs 10 live)
  // This should trigger compaction (dead > 50% threshold)
  for (let round = 0; round < 20; round++) {
    for (let i = 0; i < 10; i++) {
      await coll.updateOne(
        { idx: i },
        { $set: { data: `round-${round}-` + 'b'.repeat(500) } }
      );
    }
  }

  // After compaction, file should be smaller than the pre-compaction peak
  // (We can't measure the peak exactly, but the final size should be reasonable)
  const sizeAfterCompaction = getDataFileSize(tmpDir, 'compactdb', 'shrinktest');

  // The file should not be 20x the insert size since compaction should have run
  // With 10 live records of ~530 bytes each, the file should be roughly that
  // plus header overhead. Without compaction it would be 210 * ~530 bytes.
  const maxExpectedSize = sizeAfterInsert * 5; // generous upper bound
  expect(sizeAfterCompaction).toBeLessThanOrEqual(maxExpectedSize);

  // All documents should still be readable and correct
  const count = await coll.countDocuments();
  expect(count).toEqual(10);

  for (let i = 0; i < 10; i++) {
    const doc = await coll.findOne({ idx: i });
    expect(doc).toBeTruthy();
    expect(doc!.data.startsWith('round-19-')).toBeTrue();
  }
});

// ============================================================================
// Compaction: Persistence after compaction + restart
// ============================================================================

tap.test('compaction: data survives compaction + restart', async () => {
  await client.close();
  await server.stop();

  server = new smartdb.SmartdbServer({
    socketPath: path.join(os.tmpdir(), `smartdb-compact-${Date.now()}-${Math.random().toString(36).slice(2)}.sock`),
    storage: 'file',
    storagePath: tmpDir,
  });
  await server.start();

  client = new MongoClient(server.getConnectionUri(), {
    directConnection: true,
    serverSelectionTimeoutMS: 5000,
  });
  await client.connect();
  db = client.db('compactdb');

  // Verify shrinktest data
  const coll = db.collection('shrinktest');
  const count = await coll.countDocuments();
  expect(count).toEqual(10);

  for (let i = 0; i < 10; i++) {
    const doc = await coll.findOne({ idx: i });
    expect(doc).toBeTruthy();
    expect(doc!.data.startsWith('round-19-')).toBeTrue();
  }

  // Verify growing collection
  const growing = db.collection('growing');
  const growDoc = await growing.findOne({ key: 'target' });
  expect(growDoc).toBeTruthy();
  expect(growDoc!.counter).toEqual(50);

  // Verify tombstones collection is empty
  const tombCount = await db.collection('tombstones').countDocuments();
  expect(tombCount).toEqual(0);
});

// ============================================================================
// Compaction: Mixed operations stress test
// ============================================================================

tap.test('compaction: mixed insert-update-delete stress test', async () => {
  const coll = db.collection('stress');

  // Phase 1: Insert 200 documents
  const batch = [];
  for (let i = 0; i < 200; i++) {
    batch.push({ idx: i, value: `initial-${i}`, alive: true });
  }
  await coll.insertMany(batch);

  // Phase 2: Update every even-indexed document
  for (let i = 0; i < 200; i += 2) {
    await coll.updateOne({ idx: i }, { $set: { value: `updated-${i}` } });
  }

  // Phase 3: Delete every document where idx % 3 === 0
  await coll.deleteMany({ idx: { $in: Array.from({ length: 67 }, (_, k) => k * 3) } });

  // Verify: documents where idx % 3 !== 0 should remain
  const remaining = await coll.find({}).toArray();
  for (const doc of remaining) {
    expect(doc.idx % 3).not.toEqual(0);
    if (doc.idx % 2 === 0) {
      expect(doc.value).toEqual(`updated-${doc.idx}`);
    } else {
      expect(doc.value).toEqual(`initial-${doc.idx}`);
    }
  }

  // Count should be 200 - 67 = 133
  const count = await coll.countDocuments();
  expect(count).toEqual(133);
});

// ============================================================================
// Cleanup
// ============================================================================

tap.test('compaction: cleanup', async () => {
  await client.close();
  await server.stop();
  cleanTmpDir(tmpDir);
});

export default tap.start();