/**
 * Comprehensive Transaction Example
 *
 * Demonstrates distributed transactions with ACID-like semantics
 */

import {
  createConfig,
  ElasticsearchConnectionManager,
  LogLevel,
  createTransactionManager,
  type TransactionCallbacks,
  type ConflictInfo,
} from '../../index.js';

interface BankAccount {
  accountId: string;
  balance: number;
  currency: string;
  lastUpdated: Date;
}

interface Order {
  orderId: string;
  customerId: string;
  items: Array<{ productId: string; quantity: number; price: number }>;
  total: number;
  status: 'pending' | 'confirmed' | 'cancelled';
  createdAt: Date;
}

interface Inventory {
  productId: string;
  quantity: number;
  reserved: number;
  lastUpdated: Date;
}

async function main() {
  console.log('=== Transaction System Example ===\n');

  // ============================================================================
  // Step 1: Configuration
  // ============================================================================

  console.log('Step 1: Configuring Elasticsearch connection...');
  const config = createConfig()
    .fromEnv()
    .nodes(process.env.ELASTICSEARCH_URL || 'http://localhost:9200')
    .basicAuth(
      process.env.ELASTICSEARCH_USERNAME || 'elastic',
      process.env.ELASTICSEARCH_PASSWORD || 'changeme'
    )
    .timeout(30000)
    .retries(3)
    .logLevel(LogLevel.INFO)
    .enableMetrics(true)
    .build();

  // ============================================================================
  // Step 2: Initialize Connection and Transaction Manager
  // ============================================================================

  console.log('Step 2: Initializing connection and transaction manager...');
  const connectionManager = ElasticsearchConnectionManager.getInstance(config);
  await connectionManager.initialize();

  const transactionManager = createTransactionManager({
    defaultIsolationLevel: 'read_committed',
    defaultLockingStrategy: 'optimistic',
    defaultTimeout: 30000,
    maxConcurrentTransactions: 100,
    conflictResolution: 'retry',
    enableLogging: true,
    enableMetrics: true,
  });

  await transactionManager.initialize();
  console.log('✓ Connection and transaction manager initialized\n');

  // ============================================================================
  // Step 3: Setup Test Data
  // ============================================================================

  console.log('Step 3: Setting up test data...');
  const client = connectionManager.getClient();

  // Create test indices
  for (const index of ['accounts', 'orders', 'inventory']) {
    try {
      await client.indices.create({ index });
    } catch (error) {
      // Index might already exist
    }
  }

  // Create test accounts
  await client.index({
    index: 'accounts',
    id: 'acc-001',
    document: {
      accountId: 'acc-001',
      balance: 1000,
      currency: 'USD',
      lastUpdated: new Date(),
    },
  });

  await client.index({
    index: 'accounts',
    id: 'acc-002',
    document: {
      accountId: 'acc-002',
      balance: 500,
      currency: 'USD',
      lastUpdated: new Date(),
    },
  });

  // Create test inventory
  await client.index({
    index: 'inventory',
    id: 'prod-001',
    document: {
      productId: 'prod-001',
      quantity: 100,
      reserved: 0,
      lastUpdated: new Date(),
    },
  });

  console.log('✓ Test data created\n');

  // ============================================================================
  // Step 4: Simple Transaction - Money Transfer
  // ============================================================================

  console.log('Step 4: Simple transaction - money transfer...');

  const transferTxn = await transactionManager.begin({
    isolationLevel: 'read_committed',
    autoRollback: true,
  });

  try {
    // Read source account
    const sourceAccount = await transferTxn.read<BankAccount>('accounts', 'acc-001');
    console.log(`  Source balance before: $${sourceAccount?.balance}`);

    // Read destination account
    const destAccount = await transferTxn.read<BankAccount>('accounts', 'acc-002');
    console.log(`  Destination balance before: $${destAccount?.balance}`);

    // Transfer amount
    const transferAmount = 200;

    if (!sourceAccount || sourceAccount.balance < transferAmount) {
      throw new Error('Insufficient funds');
    }

    // Update source account
    await transferTxn.update<BankAccount>('accounts', 'acc-001', {
      balance: sourceAccount.balance - transferAmount,
      lastUpdated: new Date(),
    });

    // Update destination account
    await transferTxn.update<BankAccount>('accounts', 'acc-002', {
      balance: destAccount!.balance + transferAmount,
      lastUpdated: new Date(),
    });

    // Commit transaction
    const result = await transferTxn.commit();

    console.log(`  ✓ Transfer completed`);
    console.log(`    Operations: ${result.operationsExecuted}`);
    console.log(`    Duration: ${result.duration}ms`);
  } catch (error: any) {
    console.log(`  ✗ Transfer failed: ${error.message}`);
  }

  console.log();

  // ============================================================================
  // Step 5: Transaction with Rollback
  // ============================================================================

  console.log('Step 5: Transaction with rollback...');

  const rollbackTxn = await transactionManager.begin({
    autoRollback: true,
  });

  try {
    const account = await rollbackTxn.read<BankAccount>('accounts', 'acc-001');
    console.log(`  Balance before: $${account?.balance}`);

    // Update account
    await rollbackTxn.update<BankAccount>('accounts', 'acc-001', {
      balance: account!.balance + 500,
      lastUpdated: new Date(),
    });

    // Simulate error
    throw new Error('Simulated error - transaction will rollback');
  } catch (error: any) {
    console.log(`  ✗ Error occurred: ${error.message}`);
    const result = await rollbackTxn.rollback();
    console.log(`  ✓ Transaction rolled back`);
    console.log(`    Operations rolled back: ${result.operationsRolledBack}`);
  }

  // Verify balance unchanged
  const accountAfter = await client.get({ index: 'accounts', id: 'acc-001' });
  console.log(`  Balance after rollback: $${(accountAfter._source as BankAccount).balance}`);

  console.log();

  // ============================================================================
  // Step 6: Transaction with Savepoints
  // ============================================================================

  console.log('Step 6: Transaction with savepoints...');

  const savepointTxn = await transactionManager.begin();

  try {
    const account = await savepointTxn.read<BankAccount>('accounts', 'acc-001');
    console.log(`  Initial balance: $${account?.balance}`);

    // First operation
    await savepointTxn.update<BankAccount>('accounts', 'acc-001', {
      balance: account!.balance + 100,
    });

    console.log('  Operation 1: +$100');

    // Create savepoint
    savepointTxn.savepoint('after_first_op');

    // Second operation
    await savepointTxn.update<BankAccount>('accounts', 'acc-001', {
      balance: account!.balance + 200,
    });

    console.log('  Operation 2: +$200');

    // Rollback to savepoint (removes operation 2)
    savepointTxn.rollbackTo('after_first_op');
    console.log('  Rolled back to savepoint (operation 2 removed)');

    // Commit transaction (only operation 1 will be committed)
    await savepointTxn.commit();

    console.log('  ✓ Transaction committed (only operation 1)');
  } catch (error: any) {
    console.log(`  ✗ Error: ${error.message}`);
    await savepointTxn.rollback();
  }

  console.log();

  // ============================================================================
  // Step 7: Concurrent Transactions with Conflict
  // ============================================================================

  console.log('Step 7: Concurrent transactions with conflict handling...');

  let conflictsDetected = 0;

  const callbacks: TransactionCallbacks = {
    onConflict: async (conflict: ConflictInfo) => {
      conflictsDetected++;
      console.log(`  ⚠ Conflict detected on ${conflict.operation.index}/${conflict.operation.id}`);
      return 'retry'; // Automatically retry
    },
  };

  // Start two concurrent transactions modifying the same document
  const txn1 = transactionManager.begin({ maxRetries: 5 }, callbacks);
  const txn2 = transactionManager.begin({ maxRetries: 5 }, callbacks);

  const [transaction1, transaction2] = await Promise.all([txn1, txn2]);

  try {
    // Both read the same account
    const [account1, account2] = await Promise.all([
      transaction1.read<BankAccount>('accounts', 'acc-001'),
      transaction2.read<BankAccount>('accounts', 'acc-001'),
    ]);

    console.log(`  Initial balance (txn1): $${account1?.balance}`);
    console.log(`  Initial balance (txn2): $${account2?.balance}`);

    // Both try to update
    await transaction1.update<BankAccount>('accounts', 'acc-001', {
      balance: account1!.balance + 50,
    });

    await transaction2.update<BankAccount>('accounts', 'acc-001', {
      balance: account2!.balance + 75,
    });

    // Commit both (one will conflict and retry)
    const [result1, result2] = await Promise.all([
      transaction1.commit(),
      transaction2.commit(),
    ]);

    console.log(`  ✓ Transaction 1: ${result1.success ? 'committed' : 'failed'}`);
    console.log(`  ✓ Transaction 2: ${result2.success ? 'committed' : 'failed'}`);
    console.log(`  Conflicts detected and resolved: ${conflictsDetected}`);
  } catch (error: any) {
    console.log(`  ✗ Error: ${error.message}`);
  }

  console.log();

  // ============================================================================
  // Step 8: Complex Multi-Document Transaction - Order Processing
  // ============================================================================

  console.log('Step 8: Complex multi-document transaction - order processing...');

  const orderTxn = await transactionManager.begin({
    isolationLevel: 'repeatable_read',
    autoRollback: true,
  });

  try {
    // Create order
    const order: Order = {
      orderId: 'ord-001',
      customerId: 'cust-001',
      items: [
        { productId: 'prod-001', quantity: 5, price: 10 },
      ],
      total: 50,
      status: 'pending',
      createdAt: new Date(),
    };

    await orderTxn.create<Order>('orders', order.orderId, order);
    console.log('  Created order');

    // Check and reserve inventory
    const inventory = await orderTxn.read<Inventory>('inventory', 'prod-001');
    console.log(`  Available inventory: ${inventory?.quantity}`);

    if (!inventory || inventory.quantity < 5) {
      throw new Error('Insufficient inventory');
    }

    await orderTxn.update<Inventory>('inventory', 'prod-001', {
      quantity: inventory.quantity - 5,
      reserved: inventory.reserved + 5,
      lastUpdated: new Date(),
    });

    console.log('  Reserved inventory: 5 units');

    // Charge customer account
    const customerAccount = await orderTxn.read<BankAccount>('accounts', 'acc-001');

    if (!customerAccount || customerAccount.balance < order.total) {
      throw new Error('Insufficient funds');
    }

    await orderTxn.update<BankAccount>('accounts', 'acc-001', {
      balance: customerAccount.balance - order.total,
      lastUpdated: new Date(),
    });

    console.log(`  Charged customer: $${order.total}`);

    // Update order status
    await orderTxn.update<Order>('orders', order.orderId, {
      status: 'confirmed',
    });

    console.log('  Order confirmed');

    // Commit all operations atomically
    const result = await orderTxn.commit();

    console.log(`  ✓ Order processed successfully`);
    console.log(`    Operations: ${result.operationsExecuted}`);
    console.log(`    Duration: ${result.duration}ms`);
  } catch (error: any) {
    console.log(`  ✗ Order processing failed: ${error.message}`);
    console.log('  All changes rolled back');
  }

  console.log();

  // ============================================================================
  // Step 9: Transaction Statistics
  // ============================================================================

  console.log('Step 9: Transaction statistics...\n');

  const stats = transactionManager.getStats();

  console.log('Transaction Manager Statistics:');
  console.log(`  Total started: ${stats.totalStarted}`);
  console.log(`  Total committed: ${stats.totalCommitted}`);
  console.log(`  Total rolled back: ${stats.totalRolledBack}`);
  console.log(`  Total failed: ${stats.totalFailed}`);
  console.log(`  Total operations: ${stats.totalOperations}`);
  console.log(`  Total conflicts: ${stats.totalConflicts}`);
  console.log(`  Total retries: ${stats.totalRetries}`);
  console.log(`  Success rate: ${(stats.successRate * 100).toFixed(2)}%`);
  console.log(`  Avg duration: ${stats.avgDuration.toFixed(2)}ms`);
  console.log(`  Avg operations/txn: ${stats.avgOperationsPerTransaction.toFixed(2)}`);
  console.log(`  Active transactions: ${stats.activeTransactions}`);

  console.log();

  // ============================================================================
  // Step 10: Cleanup
  // ============================================================================

  console.log('Step 10: Cleanup...');

  await transactionManager.destroy();
  await connectionManager.destroy();

  console.log('✓ Cleanup complete\n');

  console.log('=== Transaction System Example Complete ===');
  console.log('\nKey Features Demonstrated:');
  console.log('  ✓ ACID-like transaction semantics');
  console.log('  ✓ Optimistic concurrency control');
  console.log('  ✓ Automatic rollback on error');
  console.log('  ✓ Compensation-based rollback');
  console.log('  ✓ Savepoints for partial rollback');
  console.log('  ✓ Conflict detection and retry');
  console.log('  ✓ Multi-document transactions');
  console.log('  ✓ Isolation levels (read_committed, repeatable_read)');
  console.log('  ✓ Transaction callbacks and hooks');
  console.log('  ✓ Comprehensive statistics');
}

// Run the example
main().catch((error) => {
  console.error('Example failed:', error);
  process.exit(1);
});