import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { SSEServerTransport } from '@modelcontextprotocol/sdk/server/sse.js';
import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
import { Logger } from '../utils/logger.util';
import configLoader from '../config/config-loader';
import { PACKAGE_NAME, VERSION } from '../utils/constants.util';
import posthogLlmTools from '../tools/posthog-llm.tool.js';
import openTelemetryTools from '../tools/opentelemetry-llm.tool.js';

export function createServer() {
	const serverLogger = Logger.forContext('utils/server.util.ts', 'getServer');

	// Load configuration
	serverLogger.info('Starting MCP server initialization...');
	configLoader.load();

	const commonConfig = configLoader.getCommonConfig();
	if (commonConfig.debug) {
		serverLogger.debug('Debug mode enabled');
	}

	serverLogger.info(`Initializing LLM Log MCP server v${VERSION}`);
	const server = new McpServer({
		name: PACKAGE_NAME,
		version: VERSION,
	});

	// Register tools
	serverLogger.info('Registering MCP tools...');
	posthogLlmTools.registerTools(server);
	openTelemetryTools.registerTools(server);
	serverLogger.debug('All tools registered');

	return server;
}

/**
 * Graceful shutdown handler
 */
export function shutdownServer(
	transports:
		| Record<string, SSEServerTransport | StreamableHTTPServerTransport>
		| undefined,
) {
	const shutdownLogger = Logger.forContext(
		'utils/server.util.ts',
		'shutdown',
	);

	const shutdown = async () => {
		try {
			shutdownLogger.info('Shutting down server...');

			// Close all active transports to properly clean up resources
			if (transports) {
				for (const sessionId in transports) {
					try {
						shutdownLogger.debug(
							`Closing transport for session ${sessionId}`,
						);
						const transport = transports[sessionId];
						if (
							transport &&
							'close' in transport &&
							typeof transport.close === 'function'
						) {
							await transport.close();
							delete transports[sessionId];
						}
					} catch (error) {
						shutdownLogger.error(
							`Error closing transport for session ${sessionId}:`,
							error,
						);
					}
				}
			}

			shutdownLogger.info('Server shutdown complete');
			process.exit(0);
		} catch (err) {
			shutdownLogger.error('Error during shutdown', err);
			process.exit(1);
		}
	};

	['SIGINT', 'SIGTERM'].forEach((signal) => {
		process.on(signal as NodeJS.Signals, shutdown);
	});
}