/**
 * @fileoverview Chahua Database Manager - Database Operations Module
 * @description โมดูลสำหรับการดำเนินการฐานข้อมูลผ่าน REST API
 * คุณสมบัติ: Connection testing, Query execution, Database structure retrieval
 * @author ทีมพัฒนา Chahua
 * @version 1.0.0
 * @since 2024-01-01
 * @calledBy app.js, UI components
 * @dependencies
 * - fetch API: HTTP request handling
 * - database-server.js: Backend API endpoints
 * @features
 * - Database connection testing and validation
 * - SQL query execution with error handling
 * - Database structure discovery
 * - Connection management operations
 * - HTTP error handling and retries
 * @security
 * - Input sanitization for queries
 * - Error message filtering
 * - Connection parameter validation
 * @example
 * // Test database connection
 * const dbOps = new DatabaseOperations();
 * const result = await dbOps.testConnection(connectionConfig);
 * 
 * // Execute SQL query
 * const queryResult = await dbOps.executeQuery(connectionId, 'SELECT * FROM users');
 */

// Database operations module
/**
 * Database Operations - Class for handling database operations via REST API
 * @class DatabaseOperations
 * @description Provides methods for database connection testing, query execution, and structure discovery
 * @features
 * - Connection management and testing
 * - SQL query execution with error handling
 * - Database structure discovery
 * - HTTP-based communication with backend server
 */
class DatabaseOperations {
    /**
     * Create a DatabaseOperations instance
     * @constructor
     * @description Initializes the database operations with default API base URL
     */
    constructor() {
        this.baseUrl = 'http://localhost:3001/api';
    }

    /**
     * Test database connection
     * @async
     * @function testConnection
     * @param {Object} connectionData - Database connection configuration
     * @param {string} connectionData.type - Database type (postgresql, mysql, mongodb, redis)
     * @param {string} connectionData.host - Database host
     * @param {number} connectionData.port - Database port
     * @param {string} connectionData.database - Database name
     * @param {string} connectionData.username - Username for authentication
     * @param {string} connectionData.password - Password for authentication
     * @returns {Promise<Object>} Connection test result
     * @throws {Error} Network or connection errors
     */
    async testConnection(connectionData) {
        try {
            const response = await fetch(`${this.baseUrl}/connections`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify(connectionData)
            });
            return await response.json();
        } catch (error) {
            return { success: false, error: error.message };
        }
    }

    /**
     * Get all saved connections
     * @async
     * @function getConnections
     * @returns {Promise<Object>} List of saved database connections
     * @throws {Error} Network or server errors
     */
    async getConnections() {
        try {
            const response = await fetch(`${this.baseUrl}/connections`);
            return await response.json();
        } catch (error) {
            return { success: false, error: error.message };
        }
    }

    /**
     * Execute SQL query on specified connection
     * @async
     * @function executeQuery
     * @param {string} connectionId - Unique identifier for the database connection
     * @param {string} query - SQL query to execute
     * @returns {Promise<Object>} Query execution result with data or error
     * @throws {Error} Network, query syntax, or database errors
     */
    async executeQuery(connectionId, query) {
        try {
            const response = await fetch(`${this.baseUrl}/connections/${connectionId}/query`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ query })
            });
            return await response.json();
        } catch (error) {
            return { success: false, error: error.message };
        }
    }

    /**
     * Get database structure (tables, columns, relationships)
     * @async
     * @function getDatabaseStructure
     * @param {string} connectionId - Unique identifier for the database connection
     * @returns {Promise<Object>} Database structure information
     * @throws {Error} Network or database access errors
     */
    async getDatabaseStructure(connectionId) {
        try {
            const response = await fetch(`${this.baseUrl}/connections/${connectionId}/structure`);
            return await response.json();
        } catch (error) {
            return { success: false, error: error.message };
        }
    }

    async getTableData(connectionId, tableName, page = 1, limit = 50) {
        try {
            const response = await fetch(`${this.baseUrl}/connections/${connectionId}/tables/${tableName}/data?page=${page}&limit=${limit}`);
            return await response.json();
        } catch (error) {
            return { success: false, error: error.message };
        }
    }
}

// Make it available globally
if (typeof window !== 'undefined') {
    window.DatabaseOperations = DatabaseOperations;
}