#!/usr/bin/env node
/**
 * MySQL MCP Server - Node.js 实现
 * 提供 execute_sql 工具用于执行 SQL 语句
 */

const mysql = require('mysql2/promise');
const readline = require('readline');

const config = {
    host: process.env.MYSQL_HOST || 'localhost',
    port: parseInt(process.env.MYSQL_PORT) || 3306,
    user: process.env.MYSQL_USER || 'root',
    password: process.env.MYSQL_PASSWORD || '',
    database: process.env.MYSQL_DATABASE || 'test'
};

let pool = null;

async function getPool() {
    if (!pool) {
        pool = mysql.createPool(config);
    }
    return pool;
}

async function executeSQL(query) {
    const p = await getPool();
    const [rows, fields] = await p.query(query);
    return { rows, fields };
}

function sendResponse(id, result) {
    const response = { jsonrpc: '2.0', id, result };
    process.stdout.write(JSON.stringify(response) + '\n');
}

function sendError(id, code, message) {
    const response = { jsonrpc: '2.0', id, error: { code, message } };
    process.stdout.write(JSON.stringify(response) + '\n');
}

async function handleRequest(request) {
    const { id, method, params } = request;

    try {
        switch (method) {
            case 'initialize':
                sendResponse(id, {
                    protocolVersion: '2024-11-05',
                    capabilities: { tools: {} },
                    serverInfo: { name: 'mysql-node-mcp', version: '1.0.0' }
                });
                break;

            case 'tools/list':
                sendResponse(id, {
                    tools: [{
                        name: 'execute_sql',
                        description: 'Execute SQL query on MySQL database',
                        inputSchema: {
                            type: 'object',
                            properties: {
                                query: { type: 'string', description: 'SQL query to execute' }
                            },
                            required: ['query']
                        }
                    }]
                });
                break;

            case 'tools/call':
                if (params.name === 'execute_sql') {
                    const query = params.arguments.query;
                    const result = await executeSQL(query);
                    
                    let content;
                    if (Array.isArray(result.rows) && result.rows.length > 0) {
                        content = JSON.stringify(result.rows, null, 2);
                    } else if (result.rows && result.rows.affectedRows !== undefined) {
                        content = `Rows affected: ${result.rows.affectedRows}`;
                    } else {
                        content = 'Query executed successfully';
                    }
                    
                    sendResponse(id, {
                        content: [{ type: 'text', text: content }]
                    });
                } else {
                    sendError(id, -32601, `Unknown tool: ${params.name}`);
                }
                break;

            case 'notifications/initialized':
            case 'notifications/cancelled':
                // 忽略通知
                break;

            default:
                if (id !== undefined) {
                    sendError(id, -32601, `Method not found: ${method}`);
                }
        }
    } catch (err) {
        if (id !== undefined) {
            sendError(id, -32000, err.message);
        }
    }
}

const rl = readline.createInterface({ input: process.stdin });

rl.on('line', async (line) => {
    try {
        const request = JSON.parse(line);
        await handleRequest(request);
    } catch (err) {
        // 忽略解析错误
    }
});

process.on('SIGINT', async () => {
    if (pool) await pool.end();
    process.exit(0);
});