'use strict';
const path = require('path');
const childProcess = require('child_process');
const fs = require('fs');
const stdoutWebProxyPrefix = 'gRPC Web proxy started at: ';
const { app, dialog, shell } = require('electron');
const Util = require('./util.js');
const winShutdownStdinMessage = 'shutdown\n';

let maxStdErrChunksBuffer = 10;

class Server {

	start (binPath, workingDir) {
		console.log('[Server]: start', binPath, workingDir);

		const logPath = Util.logPath();
		const env = process.env;

		return new Promise((resolve, reject) => {

			// stop will resolve immediately in case child process is not running
			this.stop().then(() => {
				this.isRunning = false;

				try {
					if (!process.stdout.isTTY) {
						env['GOLOG_FILE'] = path.join(logPath, `anytype_${Util.dateForFile()}.log`);
					};
					
					this.cp = childProcess.spawn(binPath, [ '127.0.0.1:0', '127.0.0.1:0' ], { windowsHide: false, env });
				} catch (err) {
					console.error('[Server] Process start error: ', err.toString());
					reject(err);
				};
				
				this.cp.on('error', err => {
					this.isRunning = false;
					console.error('[Server] Failed to start server: ', err.toString());
					reject(err);
				});
				
				this.cp.stdout.on('data', data => {
					const str = data.toString();

					if (!this.isRunning && str && (str.indexOf(stdoutWebProxyPrefix) >= 0)) {
						const regex = new RegExp(stdoutWebProxyPrefix + '([^\n^\s]+)');

						this.address = 'http://' + regex.exec(str)[1];
						this.isRunning = true;

						resolve(true);
					};

					// Do not delete
					console.log(str);
				});

				this.cp.stderr.on('data', data => {
					const chunk = data.toString();
					
					// max chunk size is 8192 bytes
					// https://github.com/nodejs/node/issues/12921
					// https://nodejs.org/api/buffer.html#buffer_class_property_buffer_poolsize
					
					if (chunk.length > 8000) {
						// in case we've got a crash lets change the max buffer to collect the whole stack trace
						maxStdErrChunksBuffer = 2048; // 2048x8192 = 16 Mb max
					};
					
					if (!this.lastErrors) {
						this.lastErrors = [];
					} else 
					if (this.lastErrors.length >= maxStdErrChunksBuffer) {
						this.lastErrors.shift();
					};
					
					this.lastErrors.push(chunk);
					console.log(chunk);
				});
				
				this.cp.on('exit', () => {
					if (this.stopTriggered) {
						return;
					};
					
					this.isRunning = false;
					
					const log = path.join(logPath, `crash_${Util.dateForFile()}.log`);
					try {
						fs.writeFileSync(log, this.lastErrors.join('\n'), 'utf-8');
					} catch(e) {
						console.log('[Server]: Failed to save log file', log);
					};
					
					dialog.showErrorBox('Anytype helper crashed', 'You will be redirected to the crash log file. You can send it to Anytype developers by creating issue at https://community.anytype.io');
					shell.showItemInFolder(log);
					
					app.exit(0);
				});
			});
		});
	};
	
	stop (signal) {
		signal = String(signal || 'SIGTERM');

		return new Promise((resolve, reject) => {
			if (this.cp && this.isRunning) {
				this.cp.on('exit', () => {
					resolve(true);

					this.isRunning = false;
					this.cp = null;
				});
				
				this.stopTriggered = true;
 				if (process.platform === 'win32') {
					 // it is not possible to handle os signals on windows, so we can't do graceful shutdown on go side
					this.cp.stdin.write(winShutdownStdinMessage);
				} else {
					this.cp.kill(signal);
				};
			} else {
				resolve();
			};
		});
	};

	getAddress () {
		return this.address;
	};
	
	setAddress (address) {
		this.address = address;
	};
	
};

module.exports = new Server();
