require("dotenv").config();
var child_process = require("child_process");
var EventEmitter = require("events").EventEmitter;
var colors = require("colors");
var Discord = require("discord.js");
process.chdir("/srv/jpland");

String.prototype.capitalize = function() {
    return this[0].toUpperCase() + this.substring(1);
};

var MAX_IDLE_MINUTES = 60;
var CMD_PREFIX = '%';

class MinecraftServer extends EventEmitter {
	constructor (cwd, jar) {
		super();
		this.cwd = cwd;
		this.java = "java";
		this.jvm_args = ["-Xmx4G"];
		this.jar = jar;
		this.idleMinutes = 0;
		this.locked = false;
		// paper 1.16.2
		this.listCommand = "minecraft:list"; 
		this.listEmptyRegex = /^\[\d\d:\d\d:\d\d INFO\]: There are 0 of a max of \d{1,} players online:$/;
		this.listNotEmptyRegex = /^\[\d\d:\d\d:\d\d INFO\]: There are [1-9]\d{0,} of a max of \d{1,} players online:/;
	}

	start() {
		this._log("Starting server".green);
		this.process = child_process.spawn("nice", ["-n", "1", this.java].concat(this.jvm_args).concat(["-jar", this.jar]), {cwd: this.cwd});
		this.process.on("error", error => {
			this.process.emit("exit");
			this._log(error.stack.red, true);
		});
		this.process.stdout.on("data", data => {
			data = data.toString().trim().split("\n");
			data.forEach(data => {
				this._log(data);
				this._handleOutput(data);
			});
		});
		this.process.stderr.on("data", data => {
			data = data.toString().trim().split("\n");
			this._log(data, true);
		});
		this.process.once("exit", () => {
			this.process = undefined;
			clearInterval(this.listInterval);
			this._log("Server has exited".red);
		});
		this.idleMinutes = 0;
		this.listInterval = setInterval(()=>{
			this.process.stdin.write(this.listCommand + "\n");
		}, 60000);
		return this;
	}

	stop() {
		return this.process && this.process.stdin.write("stop\n");
	}

	restart() {
		if (!this.process) return;
		this.process.on("exit", () => this.start());
		return this.stop();
	}

	_log(msg, isError) {
		return console[isError ? "error" : "log"](`[${this.cwd}]`[isError ? "red" : "green"], msg);
	}
	_handleOutput(line) {
		if (this._testIfConsoleLineIndicatesNoPlayersOnline(line)) {
			// no players are online
			this._log("Detected no players online; incrementing idleMinutes".yellow);
			this.idleMinutes++;
			if (this.idleMinutes >= MAX_IDLE_MINUTES)  {
				if (!this.locked) {
					this.idleMinutes = 0;
					this.stop();
					this._log("Shutting down due to inactivity".red);
					this.emit("idle timeout");
				} else {
					this._log("Idle timeout exceeded but ignoring because server is locked".yellow);
				}
			}
		} else if (this._testIfConsoleLineIndicatesPlayersOnline(line)) {
			// players are online
			this._log("Detected players online; resetting idle minutes".yellow);
			this.idleMinutes = 0;
		}
	}

	_testIfConsoleLineIndicatesPlayersOnline(line) {
		return this.listNotEmptyRegex.test(line);
	}

	_testIfConsoleLineIndicatesNoPlayersOnline(line) {
		return this.listEmptyRegex.test(line);
	}
	
}


var servers = {
	creative: new MinecraftServer("creative", "paper.jar"),
	survival: new MinecraftServer("survival", "paper.jar"),
	modded: new MinecraftServer("forge", "forge.jar"),
	modded2: new MinecraftServer("modded2", "forge.jar"),
	multiverse: new MinecraftServer("multiverse", "paper-1618.jar"),
};

//TODO regex but if it's not broken, don't fix it 🤷
servers.modded._testIfConsoleLineIndicatesPlayersOnline = function(line) {
	var fojat = line.substr(line.indexOf("] [Server thread/INFO] [minecraft/DedicatedServer]: There are "));
	return (fojat.startsWith("] [Server thread/INFO] [minecraft/DedicatedServer]: There are ") && fojat.endsWith(" players online:"));
}
servers.modded._testIfConsoleLineIndicatesNoPlayersOnline = function(line) {
	return line.endsWith("] [Server thread/INFO] [minecraft/DedicatedServer]: There are 0/20 players online:");
}
servers.modded.listCommand = "list";
servers.modded.java = "/usr/bin/java"; // java 8
servers.modded2._testIfConsoleLineIndicatesPlayersOnline = servers.modded._testIfConsoleLineIndicatesPlayersOnline;
servers.modded2._testIfConsoleLineIndicatesNoPlayersOnline = servers.modded._testIfConsoleLineIndicatesNoPlayersOnline;
servers.modded2.listCommand = servers.modded.listCommand;
servers.modded2.java = "/usr/bin/java";

servers.multiverse.listEmptyRegex = /^\[\d\d:\d\d:\d\d INFO\]: There are 0\/\d{1,} players online:$/;
servers.multiverse.listNotEmptyRegex = /^\[\d\d:\d\d:\d\d INFO\]: There are [1-9]\d{0,}\/\d{1,} players online:$/;


function commandHandler(input, priviledged) {
	var args = input.split(' ');
	var cmd = args[0];
	var unauthorized = "You are not permitted to perform this command.";

	var serverName = args[1] && args[1].toLowerCase();
	var server = servers[serverName];

	if (cmd == "start") {
		if (!server) return `Unknown server ${serverName}`
		if (server.process) return `${serverName.capitalize()} server is already running.`;
		server.start();
		return `Starting ${serverName} server.`;
	} else if (cmd == "stop") {
		if (!priviledged) return unauthorized;
		if (!server) return `Unknown server ${serverName}`
		if (!server.process) return `${serverName.capitalize()} server is not running.`;
		server.stop();
		return `Stopping ${serverName} server.`;
	} else if (cmd == "input") {
		if (!priviledged) return unauthorized;
		if (!server) return `Unknown server ${serverName}`
		if (!server.process) return `${serverName.capitalize()} server is not running.`;
		if (args[2] == "list" || args[2] == "minecraft:list") return "`{CMD_PREFIX}list` command is prohibited from running in console because it would interfere with idle minute counting.";
		server.process.stdin.write(args.slice(2).join(" ") + '\n');
		return;
	} else if (cmd == "list") {
		return `Servers: ${Object.keys(servers).map(x => `${x} (${servers[x].process ? 'running' : 'stopped'})`).join(', ')}`;
	} else if (cmd == "lock") {
		if (!priviledged) return unauthorized;
		if (!server) return `Unknown server ${serverName}`;
		if (server.locked = !server.locked) {
			return `${serverName.capitalize()} server will be exempt from idle timeout.`;
		} else {
			return `${serverName.capitalize()} server will no longer be exempt from idle timeout.`;
		}
	} else if (cmd == "eval") {
		if (!priviledged) return unauthorized;
		try {
			return String(eval(args.slice(1).join(' ')));
		} catch (error) {
			return String(error);
		}
	} else if (cmd == "help") {
		return "JPLand Manager automatically shuts down Minecraft servers after "+MAX_IDLE_MINUTES+" minutes to save resources, and allows you to start servers again using the `{CMD_PREFIX}start <server>` command.\n" +
			"Use `{CMD_PREFIX}list` to see the list of servers and their statuses.\n" +
			(priviledged ? "\nYou are an admin and may also use these commands: `{CMD_PREFIX}stop <server>`, `{CMD_PREFIX}input <server> <command>` (input a command into a server's console), `{CMD_PREFIX}lock <server>` (prevent automatic shutdown), `{CMD_PREFIX}eval <code>` (evaluate javascript in the Node.js process)." : "");
	} else {
		return `Unknown command \`{CMD_PREFIX}${cmd}\`, use \`{CMD_PREFIX}help\` for the list of commands.`;
	}
}

process.openStdin();
process.stdin.on("data", data => {
	data = data.toString().trim();
	var response = commandHandler(data, true);
	if (response) console.log(response.replace(/{CMD_PREFIX}/g, '').blue);
});


if (process.env.DISCORD_TOKEN) {
	var dClient = new Discord.Client();
	dClient.login(process.env.DISCORD_TOKEN);
	dClient.on("error", error => console.error(colors.red("Discord client error: " + error.message)));
	function setStatus() {
		dClient.user.setActivity(`${CMD_PREFIX}help`);
	}
	setInterval(setStatus, 1000*60*30);
	dClient.on("ready", () => {
		console.log("Discord client is ready.".green);
		setStatus();
	});
	dClient.on("message", message => {
		if (message.content.startsWith(CMD_PREFIX)) {
			let response = commandHandler(message.content.substr(CMD_PREFIX.length), message.member && message.member.guild.id == "357038384121905152" && message.member.roles.map(x => x.name).includes("Minecraft admin"));
			if (response) message.channel.send(response.replace(/{CMD_PREFIX}/g, CMD_PREFIX));
		}
	});
	for (let serverName in servers) {
		let server = servers[serverName];
		server.on("idle timeout", () => {
			let channel = dClient.channels.get("452025433328975872");
			if (channel) channel.send(`${serverName.capitalize()} server has been shut down due to 1 hour of inactivity. Run \`${CMD_PREFIX}start ${serverName}\` when you want to play on it again.`);
		});
	}
}


console.log("JPLand Manager is now running.".green);