/**
 * V3 MCP Stdio Transport
 *
 * Standard I/O transport for MCP communication:
 * - Optimized JSON parsing with streaming
 * - Buffer management for large messages
 * - Graceful shutdown handling
 *
 * Performance Targets:
 * - Message parsing: <5ms
 * - Response sending: <2ms
 */
import { EventEmitter } from 'events';
import * as readline from 'readline';
/**
 * Stdio Transport Implementation
 *
 * Uses readline for efficient line-by-line processing of JSON-RPC messages
 */
export class StdioTransport extends EventEmitter {
    logger;
    type = 'stdio';
    requestHandler;
    notificationHandler;
    rl;
    running = false;
    messageBuffer = '';
    // Statistics
    messagesReceived = 0;
    messagesSent = 0;
    errors = 0;
    inputStream;
    outputStream;
    maxMessageSize;
    constructor(logger, config = {}) {
        super();
        this.logger = logger;
        this.inputStream = config.inputStream || process.stdin;
        this.outputStream = config.outputStream || process.stdout;
        this.maxMessageSize = config.maxMessageSize || 10 * 1024 * 1024; // 10MB default
    }
    /**
     * Start the transport
     */
    async start() {
        if (this.running) {
            throw new Error('Stdio transport already running');
        }
        this.logger.info('Starting stdio transport');
        // Create readline interface for efficient line processing
        this.rl = readline.createInterface({
            input: this.inputStream,
            crlfDelay: Infinity,
        });
        // Handle incoming lines
        this.rl.on('line', (line) => {
            this.handleLine(line);
        });
        // Handle close
        this.rl.on('close', () => {
            this.handleClose();
        });
        // Handle errors on input stream
        this.inputStream.on('error', (error) => {
            this.handleError(error);
        });
        this.running = true;
        this.logger.info('Stdio transport started');
    }
    /**
     * Stop the transport
     */
    async stop() {
        if (!this.running) {
            return;
        }
        this.logger.info('Stopping stdio transport');
        this.running = false;
        if (this.rl) {
            this.rl.close();
            this.rl = undefined;
        }
        this.logger.info('Stdio transport stopped');
    }
    /**
     * Register request handler
     */
    onRequest(handler) {
        this.requestHandler = handler;
    }
    /**
     * Register notification handler
     */
    onNotification(handler) {
        this.notificationHandler = handler;
    }
    /**
     * Get health status
     */
    async getHealthStatus() {
        return {
            healthy: this.running,
            metrics: {
                messagesReceived: this.messagesReceived,
                messagesSent: this.messagesSent,
                errors: this.errors,
            },
        };
    }
    /**
     * Handle incoming line
     */
    async handleLine(line) {
        if (!line.trim()) {
            return;
        }
        // Check message size
        if (line.length > this.maxMessageSize) {
            this.logger.error('Message exceeds maximum size', {
                size: line.length,
                max: this.maxMessageSize,
            });
            this.errors++;
            return;
        }
        try {
            const message = JSON.parse(line);
            this.messagesReceived++;
            // Validate JSON-RPC format
            if (message.jsonrpc !== '2.0') {
                this.logger.warn('Invalid JSON-RPC version', { received: message.jsonrpc });
                await this.sendError(message.id, -32600, 'Invalid JSON-RPC version');
                return;
            }
            if (!message.method) {
                this.logger.warn('Missing method in request');
                await this.sendError(message.id, -32600, 'Missing method');
                return;
            }
            // Determine if this is a request or notification
            if (message.id !== undefined) {
                // Request - needs response
                await this.handleRequest(message);
            }
            else {
                // Notification - no response needed
                await this.handleNotification(message);
            }
        }
        catch (error) {
            this.errors++;
            this.logger.error('Failed to parse message', { error, line: line.substring(0, 100) });
            await this.sendError(null, -32700, 'Parse error');
        }
    }
    /**
     * Handle MCP request
     */
    async handleRequest(request) {
        if (!this.requestHandler) {
            this.logger.warn('No request handler registered');
            await this.sendError(request.id, -32603, 'No request handler');
            return;
        }
        try {
            const startTime = performance.now();
            const response = await this.requestHandler(request);
            const duration = performance.now() - startTime;
            this.logger.debug('Request processed', {
                method: request.method,
                duration: `${duration.toFixed(2)}ms`,
            });
            await this.sendResponse(response);
        }
        catch (error) {
            this.logger.error('Request handler error', { method: request.method, error });
            await this.sendError(request.id, -32603, error instanceof Error ? error.message : 'Internal error');
        }
    }
    /**
     * Handle MCP notification
     */
    async handleNotification(notification) {
        if (!this.notificationHandler) {
            this.logger.debug('Notification received but no handler', { method: notification.method });
            return;
        }
        try {
            await this.notificationHandler(notification);
        }
        catch (error) {
            this.logger.error('Notification handler error', { method: notification.method, error });
            // Notifications don't send error responses
        }
    }
    /**
     * Send response to stdout
     */
    async sendResponse(response) {
        const json = JSON.stringify(response);
        await this.write(json);
        this.messagesSent++;
    }
    /**
     * Send error response
     */
    async sendError(id, code, message) {
        const response = {
            jsonrpc: '2.0',
            id,
            error: { code, message },
        };
        await this.sendResponse(response);
        this.errors++;
    }
    /**
     * Send notification to stdout
     */
    async sendNotification(notification) {
        const json = JSON.stringify(notification);
        await this.write(json);
        this.messagesSent++;
    }
    /**
     * Write to output stream
     */
    write(data) {
        return new Promise((resolve, reject) => {
            this.outputStream.write(data + '\n', (error) => {
                if (error) {
                    this.errors++;
                    reject(error);
                }
                else {
                    resolve();
                }
            });
        });
    }
    /**
     * Handle stream close
     */
    handleClose() {
        this.logger.info('Stdio stream closed');
        this.running = false;
        this.emit('close');
    }
    /**
     * Handle stream error
     */
    handleError(error) {
        this.logger.error('Stdio stream error', error);
        this.errors++;
        this.emit('error', error);
    }
}
/**
 * Create stdio transport
 */
export function createStdioTransport(logger, config = {}) {
    return new StdioTransport(logger, config);
}
//# sourceMappingURL=stdio.js.map