// This script aims to bridge Minecraft to a guild of your choice by piping
// the Minecraft output into this script. RCON isrequired for messages to
// be sent to Minecraft.

// Running example - working directory: project root:
//  (cd ~/minecraft_server/ ; exec ~/minecraft_server/start.sh) | RCON_PASSWORD="your rcon password" node scripts/minecraft.js 

import fetch from "node-fetch";
import { WebSocket } from "ws";
import { spawn } from "node:child_process";
import Rcon from "rcon";



const TOKEN = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6InN0YWdpbmctbWluZWNyYWZ0LWJyaWRnZSIsImF2YXRhclVSTCI6bnVsbCwiZGlzY29yZElEIjoiMCIsImd1aWxkQWNjZXNzIjpbIjczNjI5MjUwOTEzNDc0OTgwNyJdLCJpc1N1cGVyVG9rZW4iOnRydWUsImlhdCI6MTY0NDQ1MzM4MX0.-XIBl6VLnXVwve9iqhWs51ABZkm1i_v1tS6X01SPk3U"; // A supertoken is required to send messages from Minecraft.
const TARGET_GUILD_ID = "_";
const TARGET_CHANNEL_ID = "_";
const ORIGIN = "http://localhost:4050";
const GATEWAY_ORIGIN = "ws://localhost:4050/gateway";


const chatMessageRegex = /^\[(?:.*?)\]: \<(?<username>[a-zA-Z0-9]+)\> (?<message>.*)/;
const joinNotificationRegex = /^\[(?:.*?)\]: (?<username>[a-zA-Z0-9]+) joined the game/;
const leaveNotificationRegex = /^\[(?:.*?)\]: (?<username>[a-zA-Z0-9]+) left the game/;
const messageSchema = { t: "number", d: "object" };
const messageTypes = {
    HELLO: 0,
    YOO: 1,
    READY: 2,
    EVENT: 3
};

const createServerChildProcess = () => {
    const serverJar = process.env.SERVER_JAR;
    if (!serverJar) {
        throw new Error("SERVER_JAR not found in env");
    }

    const serverPwd = process.env.SERVER_PWD;
    if (!serverPwd) {
        throw new Error("SERVER_PWD not found in env");
    }

    return spawn("java", [
        "-Xms1G", "-Xmx5G", "-XX:+UseG1GC", "-XX:+ParallelRefProcEnabled", "-XX:MaxGCPauseMillis=200", "-XX:+UnlockExperimentalVMOptions", "-XX:+DisableExplicitGC", "-XX:+AlwaysPreTouch", "-XX:G1NewSizePercent=30",
        "-XX:G1MaxNewSizePercent=40", "-XX:G1HeapRegionSize=8M", "-XX:G1ReservePercent=20", "-XX:G1HeapWastePercent=5", "-XX:G1MixedGCCountTarget=4", "-XX:InitiatingHeapOccupancyPercent=15", "-XX:G1MixedGCLiveThresholdPercent=90",
        "-XX:G1RSetUpdatingPauseTimePercent=5", "-XX:SurvivorRatio=32", "-XX:+PerfDisableSharedMem", "-XX:MaxTenuringThreshold=1", "-Dusing.aikars.flags=https://mcflags.emc.gs",
        "-Daikars.new.flags=true", "-jar", serverJar, "nogui"
    ], {
        cwd: serverPwd
    });
};

class GatewayClient {
    constructor(gatewayPath) {
        this.gatewayPath = gatewayPath;
        this.ws = null;
        this.token = null;
        this.user = null;
        this.onEvent = (e) => {};
    }

    connect(token) {
        if (!token)
            token = this.token;

        if (this.ws) {
            console.log("gateway: connect() but connection already exists, killing existing connection...");
            try {
                this.ws.removeAllListeners();
                this.ws.close();
                this.ws = null;
            } catch (e) {
                console.log("gateway: error while closing existing connection - it might not be established yet");
            }
        }

        console.log("gateway: connecting");

        this.ws = new WebSocket(this.gatewayPath);

        this.ws.on("message", (data, isBinary) => {
            if (isBinary) {
                console.warn("gateway: got binary data from server, ignoring...");
                return;
            }

            let message = data.toString();
            try {
                message = JSON.parse(data);
            } catch(e) {
                console.warn("gateway: got invalid JSON from server (failed to parse), ignoring...");
                return;
            }

            if (!this._checkMessageSchema(message)) {
                console.warn("gateway: got invalid JSON from server (does not match schema), ignoring...");
                return;
            }

            switch (message.t) {
                case messageTypes.HELLO: {
                    console.log("gateway: HELLO");
                    this.ws.send(JSON.stringify({
                        t: messageTypes.YOO,
                        d: {
                            token
                        }
                    }));
                    break;
                }
                case messageTypes.READY: {
                    console.log("gateway: READY");
                    this.user = message.d.user;
                    break;
                }
                case messageTypes.EVENT: {
                    this.onEvent(message.d);
                    break;
                }
                default: {
                    console.warn("gateway: got invalid JSON from server (invalid type), ignoring...");
                    return;
                }
            }
        });
        this.ws.on("open", () => {
            console.log("gateway: open");
        });
        this.ws.on("close", () => {
            console.log("gateway: closed, reconnecting in 4000ms");
            setTimeout(() => {
                console.log("gateway: reconnecting");
                this.connect(token);
            }, 4000);
        });
        this.ws.on("error", (e) => {
            console.error("gateway: error", e);
            console.log("gateway: reconnecting in 4000ms due to previous error");
            setTimeout(() => {
                console.log("gateway: reconnecting");
                this.connect(token);
            }, 4000);
        });
    }

    _checkMessageSchema(message) {
        for (const [key, value] of Object.entries(message)) {
            if (!messageSchema[key])
                return false;

            if (typeof value !== messageSchema[key])
                return false;
        }
        return true;
    }
}

class Bridge {
    constructor() {
        this.gatewayConnection = new GatewayClient(GATEWAY_ORIGIN);
        this.process = null;
        this.rconConnection = null;
        this.playerCount = 0;
        this.serverStartedAt = null;

        this.gatewayConnection.onEvent = (e) => {
            if (
                e.eventType === "MESSAGE_CREATE" &&
                e.message.channel_id === TARGET_CHANNEL_ID &&
                e.message.guild_id === TARGET_GUILD_ID &&
                !e.message.webhook_id
            ) {
                if (e.message.content === "!:mc-start") {
                    this.userRequestedServerJob();
                    return;
                } else if (e.message.content === "!:mc-status") {
                    this.sendBridgeMessageAs(TARGET_GUILD_ID,
                        TARGET_CHANNEL_ID,
                        `:scroll: **Server information**\n**Player Count**: ${this.playerCount}\n**Started**: <t:${this.serverStartedAt}:R>`,
                        null,
                        null
                    );
                    return;
                }

                this.sendMinecraftMessageAs(
                    e.message.author.username,
                    e.message.content,
                    e.message.attachments,
                    e.message.referenced_message
                );
            }
        };
    }

    rconConnect() {
        if (this.rconConnection) {
            this.rconConnection.disconnect();
            this.rconConnection = null;
        }

        this.rconConnection = new Rcon("localhost", "25575", process.env.RCON_PASSWORD);
        this.rconConnection.connect();
        this.rconConnection.on("error", (e) => {
            if (e.code === "ECONNREFUSED" && e.syscall === "connect") {
                console.warn("rcon: ECONNREFUSED, reconnecting in 5s...");
                setTimeout(() => {
                    console.log("rcon: reconnecting...");
                    this.rconConnect();
                }, 5000);
            } else {
                console.error("rcon: got error", e);
                console.error("rcon: don't know what to do, disconnecting rcon due to previous error");
                this.rconConnection.disconnect();
                this.rconConnection = null;
            }
        });
        this.rconConnection.on("connect", () => {
            this.serverStartedAt = Date.now();
            this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":zap: Server started!", null, null);
        });
    }

    start() {
        this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":bridge_at_night: The bridge server has started! Type `!:mc-start` in the chat to start the Minecraft server. Any further updates related to the server's status will be sent in this channel.", null, null);
        this.gatewayConnection.connect(TOKEN);
    }

    spawnProcess() {
        if (this.process) {
            console.warn("server job: spawnProcess(): another instance already exists");
            this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":thinking: It seems like the server is already running! If you think this is a mistake, contact the server manager.", null, null);
            return;
        }

        console.log("server job: spawning");
        this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":clock5: Starting server...", null, null);

        this.process = createServerChildProcess();

        process.stdin.pipe(this.process.stdin);

        this.process.stderr.on("data", async (rawDataBuffer) => {
            const stringData = rawDataBuffer.toString().trim();
            console.error(`[server process stderr]: ${stringData}`);
        });

        this.process.stdout.on("data", async (rawDataBuffer) => {
            const stringData = rawDataBuffer.toString().trim();
            console.log(`[server process stdout]: ${stringData}`);
    
            const joinResult = joinNotificationRegex.exec(stringData);
            if (joinResult) {
                this.onPlayerCountUpdate(1);
                await this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, `:door: **${joinResult.groups.username}** joined the game. Player count is ${this.playerCount}.`, null, null);
                return;
            }
    
            const leaveResult = leaveNotificationRegex.exec(stringData);
            if (leaveResult) {
                this.onPlayerCountUpdate(-1);
                await this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, `:door: **${leaveResult.groups.username}** left the game. Player count is ${this.playerCount}.`, null, null);
                return;
            }
    
            const messageResult = chatMessageRegex.exec(stringData);
            if (messageResult) {
                await this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, messageResult.groups.message, messageResult.groups.username, null);
            }
        });

        this.process.on("spawn", () => {
            console.log("server process: spawn");
            this.process.stdout.resume();
            this.process.stderr.resume();
            this.rconConnect();
        });
    
        this.process.on("exit", (code) => {
            console.log(`server process: exited with code ${code}`);
            this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":zap: Server is now closed.", null, null);
            this.process = null;
        });

        this.process.on("error", (e) => {
            console.error("server process: error", e);
            this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":flushed: Server process error.", null, null);
            this.process = null;
        });
    }

    async sendBridgeMessageAs(guildId, channelId, content, username=undefined, avatarURL=undefined) {
        return await fetch(`${ORIGIN}/api/v1/guilds/${guildId}/channels/${channelId}/messages/create`, {
            method: "POST",
            body: JSON.stringify({
                content,
                username,
                avatarURL
            }),
            headers: {
                "content-type": "application/json",
                "authorization": TOKEN
            }
        });
    }

    sendMinecraftMessageAs(username, content, attachments=[], referencedMessage=null) {  
        const tellrawPayload = [
            { text: "[" },
            { text: `${username}`, color: "gray" },
            { text: "]" },
            { text: " " },
        ];
    
        if (referencedMessage) {
            let trimmedContent = referencedMessage.content.substring(0, 70);
            if (trimmedContent !== referencedMessage.content) {
                trimmedContent += "...";
            }
            tellrawPayload.push({
                text: `<replying to ${referencedMessage.author.username}: ${trimmedContent}>`,
                color: "gray"
            });
            tellrawPayload.push({
                text: " "
            });
        }
    
        attachments.forEach((e) => {
            tellrawPayload.push({
                text: `<open attachment: ${e.filename || "[unknown]"}>`,
                color: "gray",
                clickEvent: {
                    action: "open_url",
                    value: e.proxy_url
                }
            });
            tellrawPayload.push({
                text: " "
            });
        });
    
        tellrawPayload.push({ text: content });
        
        if (this.rconConnection)
            this.rconConnection.send(`tellraw @a ${JSON.stringify(tellrawPayload)}`);
    }

    onPlayerCountUpdate(amount) {
        this.playerCount += amount;

        if (this.playerCount === 0) {
            this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":wave: Everyone has left the server. Closing...", null, null);
            console.log("server job: playerCount has reached 0, will close child server process");
            if (this.process) {
                console.log("server job: closing process...");
                this.process.kill("SIGINT");
            } else {
                console.warn("server job: no process to kill");
            }
        }
    }

    userRequestedServerJob() {
        console.log("server job: user requested server job, spawning...");
        this.spawnProcess();

        // wait for 5 minutes - if no one has joined the server in that time, close it
        setTimeout(() => {
            if (this.playerCount === 0) {
                console.log("server job: no players on server after 5 minutes, closing...");
                this.sendBridgeMessageAs(TARGET_GUILD_ID, TARGET_CHANNEL_ID, ":pensive: Server was started, yet no one joined after 5 minutes. Closing again...", null, null);
            }
        }, 300000);
    }
}

function main() {
    const bridge = new Bridge();
    bridge.start();

    process.on("beforeExit", () => {
        if (bridge.process) {
            console.log("server process: killing on parent exit");
            bridge.process.kill("SIGINT");
        }
    });
}

main();