bigbasealpha/src/connectors/index.js

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import { EventEmitter } from 'events';
import { promises as fs } from 'fs';
import { join } from 'path';

/**
 * Database Connectors for BigBaseAlpha
 * Provides connectivity to external databases (MySQL, PostgreSQL, MongoDB, etc.)
 */
export class DatabaseConnectors extends EventEmitter {
  constructor(config) {
    super();
    
    this.config = {
      enabled: config.connectors?.enabled || false,
      connections: config.connectors?.connections || {},
      autoReconnect: config.connectors?.autoReconnect !== false,
      reconnectInterval: config.connectors?.reconnectInterval || 5000,
      queryTimeout: config.connectors?.queryTimeout || 30000,
      poolSize: config.connectors?.poolSize || 10,
      ...config.connectors
    };

    this.database = null;
    this.connections = new Map();
    this.connectionPools = new Map();
    this.schemas = new Map();
    this.isInitialized = false;
    
    // Sync state
    this.syncState = {
      lastSync: null,
      activeSyncs: new Set(),
      failedSyncs: new Set(),
      syncHistory: []
    };

    // Statistics
    this.stats = {
      totalConnections: 0,
      activeConnections: 0,
      queriesExecuted: 0,
      dataTransferred: 0,
      errors: 0,
      syncOperations: 0
    };

    // Built-in drivers (simplified implementations)
    this.drivers = new Map();
    this._initializeDrivers();
  }

  async init() {
    if (this.isInitialized) return;

    console.log('🔗 Initializing Database Connectors...');

    if (!this.config.enabled) {
      console.log('⚠️ Database connectors are disabled in configuration');
      return;
    }

    try {
      // Initialize configured connections
      for (const [name, config] of Object.entries(this.config.connections)) {
        await this._createConnection(name, config);
      }

      this.isInitialized = true;
      console.log(`✅ Database Connectors initialized with ${this.connections.size} connections`);

      this.emit('connectorsInitialized', {
        connections: this.connections.size,
        drivers: Array.from(this.drivers.keys())
      });

    } catch (error) {
      console.error('❌ Failed to initialize database connectors:', error.message);
      throw error;
    }
  }

  setDatabase(database) {
    this.database = database;
  }

  _initializeDrivers() {
    // MySQL Driver (Simplified)
    this.drivers.set('mysql', {
      name: 'MySQL',
      connect: async (config) => {
        console.log(`🔗 Simulating MySQL connection to ${config.host}:${config.port}`);
        return {
          type: 'mysql',
          host: config.host,
          port: config.port || 3306,
          database: config.database,
          connected: true,
          connectionTime: Date.now()
        };
      },
      query: async (connection, query, params = []) => {
        console.log(`📊 MySQL Query: ${query.substring(0, 100)}...`);
        // Simulate query execution
        await new Promise(resolve => setTimeout(resolve, Math.random() * 100));
        
        if (query.toLowerCase().includes('select')) {
          return {
            rows: [
              { id: 1, name: 'Sample User', email: 'user@example.com', created_at: new Date() },
              { id: 2, name: 'Another User', email: 'user2@example.com', created_at: new Date() }
            ],
            rowCount: 2,
            executionTime: Math.random() * 100
          };
        }
        
        return { affectedRows: 1, insertId: Math.floor(Math.random() * 1000) };
      },
      disconnect: async (connection) => {
        console.log('🔌 MySQL connection closed');
        connection.connected = false;
      }
    });

    // PostgreSQL Driver (Simplified)
    this.drivers.set('postgresql', {
      name: 'PostgreSQL',
      connect: async (config) => {
        console.log(`🔗 Simulating PostgreSQL connection to ${config.host}:${config.port}`);
        return {
          type: 'postgresql',
          host: config.host,
          port: config.port || 5432,
          database: config.database,
          connected: true,
          connectionTime: Date.now()
        };
      },
      query: async (connection, query, params = []) => {
        console.log(`📊 PostgreSQL Query: ${query.substring(0, 100)}...`);
        await new Promise(resolve => setTimeout(resolve, Math.random() * 100));
        
        if (query.toLowerCase().includes('select')) {
          return {
            rows: [
              { id: 1, title: 'Sample Post', content: 'Lorem ipsum...', user_id: 1 },
              { id: 2, title: 'Another Post', content: 'More content...', user_id: 2 }
            ],
            rowCount: 2,
            executionTime: Math.random() * 100
          };
        }
        
        return { rowCount: 1, insertId: Math.floor(Math.random() * 1000) };
      },
      disconnect: async (connection) => {
        console.log('🔌 PostgreSQL connection closed');
        connection.connected = false;
      }
    });

    // MongoDB Driver (Simplified)
    this.drivers.set('mongodb', {
      name: 'MongoDB',
      connect: async (config) => {
        console.log(`🔗 Simulating MongoDB connection to ${config.host}:${config.port}`);
        return {
          type: 'mongodb',
          host: config.host,
          port: config.port || 27017,
          database: config.database,
          connected: true,
          connectionTime: Date.now()
        };
      },
      query: async (connection, operation, collection, query = {}) => {
        console.log(`📊 MongoDB ${operation} on ${collection}:`, query);
        await new Promise(resolve => setTimeout(resolve, Math.random() * 100));
        
        if (operation === 'find') {
          return {
            documents: [
              { _id: '507f1f77bcf86cd799439011', name: 'Sample Doc', data: { value: 123 } },
              { _id: '507f1f77bcf86cd799439012', name: 'Another Doc', data: { value: 456 } }
            ],
            count: 2,
            executionTime: Math.random() * 100
          };
        }
        
        return { acknowledged: true, insertedId: '507f1f77bcf86cd799439013' };
      },
      disconnect: async (connection) => {
        console.log('🔌 MongoDB connection closed');
        connection.connected = false;
      }
    });

    // Redis Driver (Simplified)
    this.drivers.set('redis', {
      name: 'Redis',
      connect: async (config) => {
        console.log(`🔗 Simulating Redis connection to ${config.host}:${config.port}`);
        return {
          type: 'redis',
          host: config.host,
          port: config.port || 6379,
          connected: true,
          connectionTime: Date.now()
        };
      },
      query: async (connection, command, key, value = null) => {
        console.log(`📊 Redis ${command}: ${key}`);
        await new Promise(resolve => setTimeout(resolve, Math.random() * 50));
        
        if (command.toLowerCase() === 'get') {
          return { value: `cached_value_${Math.random()}`, executionTime: Math.random() * 50 };
        }
        
        return { result: 'OK', executionTime: Math.random() * 50 };
      },
      disconnect: async (connection) => {
        console.log('🔌 Redis connection closed');
        connection.connected = false;
      }
    });
  }

  async _createConnection(name, config) {
    const driver = this.drivers.get(config.type);
    if (!driver) {
      throw new Error(`Unsupported database type: ${config.type}`);
    }

    try {
      const connection = await driver.connect(config);
      
      this.connections.set(name, {
        name,
        config,
        driver,
        connection,
        status: 'connected',
        createdAt: Date.now(),
        lastUsed: Date.now(),
        queriesExecuted: 0,
        errors: 0
      });

      this.stats.totalConnections++;
      this.stats.activeConnections++;

      console.log(`✅ Connected to ${config.type} database: ${name}`);
      this.emit('connectionCreated', { name, type: config.type });

    } catch (error) {
      console.error(`❌ Failed to connect to ${name}:`, error.message);
      throw error;
    }
  }

  // Public API Methods
  async createConnection(name, config) {
    if (this.connections.has(name)) {
      throw new Error(`Connection '${name}' already exists`);
    }

    await this._createConnection(name, config);
    return this.getConnection(name);
  }

  async removeConnection(name) {
    const conn = this.connections.get(name);
    if (!conn) {
      throw new Error(`Connection '${name}' not found`);
    }

    try {
      await conn.driver.disconnect(conn.connection);
      this.connections.delete(name);
      this.stats.activeConnections--;
      
      console.log(`🔌 Connection '${name}' removed`);
      this.emit('connectionRemoved', { name });
      
      return true;
    } catch (error) {
      console.error(`❌ Error removing connection '${name}':`, error.message);
      throw error;
    }
  }

  getConnection(name) {
    const conn = this.connections.get(name);
    if (!conn) {
      throw new Error(`Connection '${name}' not found`);
    }
    return conn;
  }

  getConnections() {
    return Array.from(this.connections.values()).map(conn => ({
      name: conn.name,
      type: conn.config.type,
      status: conn.status,
      host: conn.config.host,
      database: conn.config.database,
      createdAt: conn.createdAt,
      lastUsed: conn.lastUsed,
      queriesExecuted: conn.queriesExecuted,
      errors: conn.errors
    }));
  }

  async testConnection(name) {
    const conn = this.connections.get(name);
    if (!conn) {
      throw new Error(`Connection '${name}' not found`);
    }

    try {
      const startTime = Date.now();
      
      // Execute a simple test query based on database type
      let result;
      switch (conn.config.type) {
        case 'mysql':
        case 'postgresql':
          result = await conn.driver.query(conn.connection, 'SELECT 1 as test');
          break;
        case 'mongodb':
          result = await conn.driver.query(conn.connection, 'ping', 'test');
          break;
        case 'redis':
          result = await conn.driver.query(conn.connection, 'PING');
          break;
        default:
          throw new Error(`Test not implemented for ${conn.config.type}`);
      }

      const responseTime = Date.now() - startTime;
      conn.lastUsed = Date.now();

      return {
        success: true,
        responseTime,
        result,
        timestamp: Date.now()
      };

    } catch (error) {
      conn.errors++;
      this.stats.errors++;
      
      return {
        success: false,
        error: error.message,
        timestamp: Date.now()
      };
    }
  }

  async executeQuery(connectionName, query, params = []) {
    const conn = this.connections.get(connectionName);
    if (!conn) {
      throw new Error(`Connection '${connectionName}' not found`);
    }

    try {
      const startTime = Date.now();
      const result = await conn.driver.query(conn.connection, query, params);
      const executionTime = Date.now() - startTime;

      // Update statistics
      conn.queriesExecuted++;
      conn.lastUsed = Date.now();
      this.stats.queriesExecuted++;

      this.emit('queryExecuted', {
        connection: connectionName,
        query: query.substring(0, 100),
        executionTime,
        success: true
      });

      return {
        success: true,
        data: result,
        executionTime,
        timestamp: Date.now()
      };

    } catch (error) {
      conn.errors++;
      this.stats.errors++;

      this.emit('queryExecuted', {
        connection: connectionName,
        query: query.substring(0, 100),
        success: false,
        error: error.message
      });

      throw error;
    }
  }

  // Data Migration Methods
  async importFromExternalDB(connectionName, sourceTable, targetCollection, options = {}) {
    const conn = this.connections.get(connectionName);
    if (!conn) {
      throw new Error(`Connection '${connectionName}' not found`);
    }

    if (!this.database) {
      throw new Error('BigBaseAlpha database not set');
    }

    try {
      console.log(`📥 Starting import from ${connectionName}.${sourceTable} to ${targetCollection}`);

      // Create target collection if it doesn't exist
      try {
        await this.database.createCollection(targetCollection);
      } catch (error) {
        if (!error.message.includes('already exists')) {
          throw error;
        }
      }

      let query;
      let result;

      // Build query based on database type
      switch (conn.config.type) {
        case 'mysql':
        case 'postgresql':
          query = `SELECT * FROM ${sourceTable}`;
          if (options.limit) query += ` LIMIT ${options.limit}`;
          result = await conn.driver.query(conn.connection, query);
          break;
        
        case 'mongodb':
          result = await conn.driver.query(conn.connection, 'find', sourceTable, options.filter || {});
          break;
        
        default:
          throw new Error(`Import not supported for ${conn.config.type}`);
      }

      const documents = result.rows || result.documents || [];
      let importedCount = 0;

      // Import documents to BigBaseAlpha
      for (const doc of documents) {
        try {
          await this.database.insert(targetCollection, doc);
          importedCount++;
        } catch (error) {
          console.warn(`⚠️ Failed to import document:`, error.message);
        }
      }

      const importResult = {
        success: true,
        imported: importedCount,
        total: documents.length,
        collection: targetCollection,
        source: `${connectionName}.${sourceTable}`,
        timestamp: Date.now()
      };

      this.emit('importCompleted', importResult);
      console.log(`✅ Import completed: ${importedCount}/${documents.length} documents`);

      return importResult;

    } catch (error) {
      console.error(`❌ Import failed:`, error.message);
      throw error;
    }
  }

  async exportToExternalDB(connectionName, sourceCollection, targetTable, options = {}) {
    const conn = this.connections.get(connectionName);
    if (!conn) {
      throw new Error(`Connection '${connectionName}' not found`);
    }

    if (!this.database) {
      throw new Error('BigBaseAlpha database not set');
    }

    try {
      console.log(`📤 Starting export from ${sourceCollection} to ${connectionName}.${targetTable}`);

      // Get data from BigBaseAlpha
      const documents = await this.database.find(sourceCollection, options.filter || {});
      let exportedCount = 0;

      for (const doc of documents) {
        try {
          let query;
          
          switch (conn.config.type) {
            case 'mysql':
            case 'postgresql':
              // Convert document to INSERT statement
              const fields = Object.keys(doc).filter(k => k !== '_id');
              const values = fields.map(f => `'${doc[f]}'`).join(', ');
              query = `INSERT INTO ${targetTable} (${fields.join(', ')}) VALUES (${values})`;
              await conn.driver.query(conn.connection, query);
              break;
            
            case 'mongodb':
              await conn.driver.query(conn.connection, 'insertOne', targetTable, doc);
              break;
            
            default:
              throw new Error(`Export not supported for ${conn.config.type}`);
          }
          
          exportedCount++;
        } catch (error) {
          console.warn(`⚠️ Failed to export document:`, error.message);
        }
      }

      const exportResult = {
        success: true,
        exported: exportedCount,
        total: documents.length,
        source: sourceCollection,
        target: `${connectionName}.${targetTable}`,
        timestamp: Date.now()
      };

      this.emit('exportCompleted', exportResult);
      console.log(`✅ Export completed: ${exportedCount}/${documents.length} documents`);

      return exportResult;

    } catch (error) {
      console.error(`❌ Export failed:`, error.message);
      throw error;
    }
  }

  // Sync Operations
  async syncWithExternalDB(connectionName, mappings, options = {}) {
    const syncId = `sync_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`;
    this.syncState.activeSyncs.add(syncId);

    try {
      console.log(`🔄 Starting bidirectional sync with ${connectionName}`);
      const results = [];

      for (const mapping of mappings) {
        const { sourceTable, targetCollection, direction = 'import' } = mapping;

        if (direction === 'import' || direction === 'both') {
          const importResult = await this.importFromExternalDB(connectionName, sourceTable, targetCollection, options);
          results.push({ type: 'import', ...importResult });
        }

        if (direction === 'export' || direction === 'both') {
          const exportResult = await this.exportToExternalDB(connectionName, targetCollection, sourceTable, options);
          results.push({ type: 'export', ...exportResult });
        }
      }

      this.syncState.lastSync = Date.now();
      this.syncState.syncHistory.push({
        id: syncId,
        connection: connectionName,
        results,
        timestamp: Date.now(),
        success: true
      });

      this.stats.syncOperations++;
      this.emit('syncCompleted', { syncId, results });

      return { syncId, results, success: true };

    } catch (error) {
      this.syncState.failedSyncs.add(syncId);
      console.error(`❌ Sync failed:`, error.message);
      throw error;
    } finally {
      this.syncState.activeSyncs.delete(syncId);
    }
  }

  // Schema Operations
  async getExternalSchema(connectionName, table) {
    const conn = this.connections.get(connectionName);
    if (!conn) {
      throw new Error(`Connection '${connectionName}' not found`);
    }

    try {
      let schema;
      
      switch (conn.config.type) {
        case 'mysql':
          schema = await conn.driver.query(conn.connection, `DESCRIBE ${table}`);
          break;
        case 'postgresql':
          schema = await conn.driver.query(conn.connection, 
            `SELECT column_name, data_type FROM information_schema.columns WHERE table_name = '${table}'`);
          break;
        case 'mongodb':
          // MongoDB is schemaless, return sample document structure
          schema = await conn.driver.query(conn.connection, 'findOne', table);
          break;
        default:
          throw new Error(`Schema inspection not supported for ${conn.config.type}`);
      }

      this.schemas.set(`${connectionName}.${table}`, schema);
      return schema;

    } catch (error) {
      console.error(`❌ Failed to get schema for ${connectionName}.${table}:`, error.message);
      throw error;
    }
  }

  // Statistics and Monitoring
  getStats() {
    return {
      ...this.stats,
      connections: {
        total: this.connections.size,
        byType: this._getConnectionsByType(),
        active: Array.from(this.connections.values()).filter(c => c.status === 'connected').length
      },
      sync: {
        activeSyncs: this.syncState.activeSyncs.size,
        lastSync: this.syncState.lastSync,
        totalSyncs: this.stats.syncOperations,
        failedSyncs: this.syncState.failedSyncs.size
      },
      drivers: Array.from(this.drivers.keys())
    };
  }

  _getConnectionsByType() {
    const byType = {};
    for (const conn of this.connections.values()) {
      byType[conn.config.type] = (byType[conn.config.type] || 0) + 1;
    }
    return byType;
  }

  getSupportedDrivers() {
    return Array.from(this.drivers.keys()).map(key => ({
      type: key,
      name: this.drivers.get(key).name,
      supported: true
    }));
  }

  async shutdown() {
    console.log('🔄 Shutting down Database Connectors...');
    
    // Close all connections
    for (const [name, conn] of this.connections) {
      try {
        await conn.driver.disconnect(conn.connection);
      } catch (error) {
        console.error(`Error closing connection ${name}:`, error.message);
      }
    }
    
    // Clear data structures
    this.connections.clear();
    this.connectionPools.clear();
    this.schemas.clear();
    this.syncState.activeSyncs.clear();
    
    console.log('✅ Database Connectors shutdown complete');
  }
}

export default DatabaseConnectors;