import { createLogger } from '@gongt/ts-stl-library/debug/create-logger';
import { LOG_LEVEL } from '@gongt/ts-stl-library/debug/levels';
import { Application } from 'express-serve-static-core';
import { createServer, Server } from 'http';
import { createWaiter, IWaitter } from '../boot/wait';
import { getWebAppListenPort } from '../communication/listen';
import { globalWorkingCallback } from '../boot/gracefull';

const info = createLogger(LOG_LEVEL.INFO, 'express.load');
const sill = createLogger(LOG_LEVEL.SILLY, 'express.load');

export type ExpressApplicationCreator = () => Application;

let wait: IWaitter;
let waitPromise: Promise<void>;

function initWaiter() {
	if (!wait) {
		sill('create express boot waiter.');
		waitPromise = new Promise((resolve, reject) => {
			wait = createWaiter((err) => {
				sill('express boot wait complete.');
				wait = null;
				waitPromise = null;
				if (err) {
					reject(err);
				} else {
					resolve();
				}
			});
		});
	}
}

export function expressWait(what: string, promise: Promise<any>) {
	sill('expressWait(%s)', what);
	initWaiter();
	wait(what, promise);
}

export function bootExpressApp(appOrCreate: Application|ExpressApplicationCreator): Promise<Server> {
	let app: Application;
	if (appOrCreate.constructor === Function) {
		sill('bootExpressApp(creator: %s)', appOrCreate.name);
		app = (<any>appOrCreate)();
	} else {
		sill('bootExpressApp(application)');
		app = (<any>appOrCreate);
	}
	process.emit('express:build' as any, app as any);
	if (wait) {
		return waitPromise.then(() => {
			wait = null;
			return bootExpressAppInternal(app);
		});
	} else {
		return bootExpressAppInternal(app);
	}
}

function bootExpressAppInternal(app: Application): Promise<Server> {
	const appPort = getWebAppListenPort();
	sill('express will listen to port: %s', appPort);
	return new Promise<any>((resolve, reject) => {
		app.set('port', appPort);
		process.emit('express:start' as any, app as any);
		
		const server = createServer(app);
		server.listen(appPort);
		
		globalWorkingCallback('express-server@' + appPort, server);
		
		server.on('error', onError);
		server.on('listening', onListening);
		
		/**
		 * Event listener for HTTP server "error" event.
		 */
		function onError(error) {
			if (error.syscall !== 'listen') {
				return reject(error);
			}
			
			const bind = typeof appPort === 'string'
				? 'Pipe ' + appPort
				: 'Port ' + appPort;
			
			// handle specific listen errors with friendly messages
			switch (error.code) {
			case 'EACCES':
				console.error(bind + ' requires elevated privileges');
				break;
			case 'EADDRINUSE':
				console.error(bind + ' is already in use');
				break;
			}
			reject(error);
		}
		
		/**
		 * Event listener for HTTP server "listening" event.
		 */
		function onListening() {
			const addr = server.address();
			const bind = typeof addr === 'string'
				? 'pipe ' + addr
				: 'port ' + addr.port;
			info('express is up, listen on port \x1B[38;5;10m%s\x1B[0m', bind);
			process.emit('express:listen' as any, server as any);
			resolve(server);
		}
	});
}