import EventEmitter from "events";
import * as net from "net";
import * as dgram from "dgram";
import { Buffer } from "buffer";
import type TypedEmitter from "typed-emitter";

type Events = {
  error: (error: Error) => void;
  auth: () => void;
  response: (response: string) => void;
  connect: () => void;
  end: () => void;
  done: () => void;
};

export const PacketType = {
  COMMAND: 0x02,
  AUTH: 0x03,
  RESPONSE_VALUE: 0x00,
  RESPONSE_AUTH: 0x02,
};

interface Options {
  tcp?: boolean;
  challenge?: boolean;
  id?: number;
}
export class Rcon extends (EventEmitter as new () => TypedEmitter<Events>) {
  private host: string;
  private port: number;
  private password: string;
  private rconId: number;
  private hasAuthed: boolean;
  private outstandingData: Uint8Array | null;
  private tcp: boolean;
  private challenge: boolean;
  private _challengeToken: string;
  private _tcpSocket!: net.Socket;
  private _udpSocket!: dgram.Socket;

  constructor(host: string, port: number, password: string, options?: Options) {
    super();
    options = options || {};
    this.host = host;
    this.port = port;
    this.password = password;
    this.rconId = options.id || 0x0012d4a6; // This is arbitrary in most cases
    this.hasAuthed = false;
    this.outstandingData = null;
    this.tcp = options.tcp ? options.tcp : true;
    this.challenge = options.challenge ? options.challenge : true;
    this._challengeToken = "";
  }

  public send = (data: string, cmd?: number, id?: number): void => {
    let sendBuf: Buffer;
    if (this.tcp) {
      cmd = cmd || PacketType.COMMAND;
      id = id || this.rconId;

      const length = Buffer.byteLength(data);
      sendBuf = Buffer.alloc(length + 14);
      sendBuf.writeInt32LE(length + 10, 0);
      sendBuf.writeInt32LE(id, 4);
      sendBuf.writeInt32LE(cmd, 8);
      sendBuf.write(data, 12);
      sendBuf.writeInt16LE(0, length + 12);
    } else {
      if (this.challenge && !this._challengeToken) {
        this.emit("error", new Error("Not authenticated"));
        return;
      }
      let str = "rcon ";
      if (this._challengeToken) str += this._challengeToken + " ";
      if (this.password) str += this.password + " ";
      str += data + "\n";
      sendBuf = Buffer.alloc(4 + Buffer.byteLength(str));
      sendBuf.writeInt32LE(-1, 0);
      sendBuf.write(str, 4);
    }
    this._sendSocket(sendBuf);
  };

  private _sendSocket = (buf: Buffer) => {
    if (this._tcpSocket) {
      this._tcpSocket.write(buf.toString("binary"), "binary");
    } else if (this._udpSocket) {
      this._udpSocket.send(buf, 0, buf.length, this.port, this.host);
    }
  };

  public connect = (): void => {
    if (this.tcp) {
      this._tcpSocket = net.createConnection(this.port, this.host);
      this._tcpSocket.on("data", (data) => {
        this._tcpSocketOnData(data);
      });
      this._tcpSocket.on("connect", () => {
        this.socketOnConnect();
      });
      this._tcpSocket.on("error", (err) => {
        //this.emit("error", err);
        this.socketOnEnd()
      });
      this._tcpSocket.on("end", () => {
        this.socketOnEnd();
      });
    } else {
      this._udpSocket = dgram.createSocket("udp4");
      this._udpSocket
        .on("message", (data) => {
          this._udpSocketOnData(data);
        })
        .on("listening", () => {
          this.socketOnConnect();
        })
        .on("error", (err) => {
          this.emit("error", err);
        })
        .on("close", () => {
          this.socketOnEnd();
        });
      this._udpSocket.bind(0);
    }
  };

  public disconnect = (): void => {
    if (this._tcpSocket) this._tcpSocket.end();
    if (this._udpSocket) this._udpSocket.close();
  };

  public setTimeout = (timeout: number, callback: () => void): void => {
    if (!this._tcpSocket) return;
    this._tcpSocket.setTimeout(timeout, () => {
      this._tcpSocket.end();
      if (callback) callback();
    });
  };

  private _udpSocketOnData = (data: Buffer) => {
    const a = data.readUInt32LE(0);
    if (a === 0xffffffff) {
      const str = data.toString("utf-8", 4);
      const tokens = str.split(" ");
      if (
        tokens.length === 3 &&
        tokens[0] === "challenge" &&
        tokens[1] === "rcon"
      ) {
        this._challengeToken = tokens[2]
          .substring(0, tokens[2].length - 1)
          .trim();
        this.hasAuthed = true;
        this.emit("auth");
      } else {
        this.emit("response", str.substring(1, str.length - 2));
      }
    } else {
      this.emit("error", new Error("Received malformed packet"));
    }
  };

  private _tcpSocketOnData = (data: Buffer) => {
    if (this.outstandingData != null) {
      data = Buffer.concat(
        [this.outstandingData, data],
        this.outstandingData.length + data.length
      );
      this.outstandingData = null;
    }

    while (data.length) {
      const len = data.readInt32LE(0);
      if (!len) return;

      const id = data.readInt32LE(4);
      const type = data.readInt32LE(8);

      if (len >= 10 && data.length >= len + 4) {
        if (id === this.rconId) {
          if (!this.hasAuthed && type === PacketType.RESPONSE_AUTH) {
            this.hasAuthed = true;
            this.emit("auth");
          } else if (type === PacketType.RESPONSE_VALUE) {
            // Read just the body of the packet (truncate the last null byte)
            // See https://developer.valvesoftware.com/wiki/Source_RCON_Protocol for details
            let str = data.toString("utf8", 12, 12 + len - 10);

            if (str.charAt(str.length - 1) === "\n") {
              // Emit the response without the newline.
              str = str.substring(0, str.length - 1);
            }

            this.emit("response", str);
          }
        } else {
          this.emit("error", new Error("Authentication failed"));
        }

        data = data.slice(12 + len - 8);
      } else {
        // Keep a reference to the chunk if it doesn't represent a full packet
        this.outstandingData = data;
        break;
      }
    }
  };

  public socketOnConnect = (): void => {
    this.emit("connect");

    if (this.tcp) {
      this.send(this.password, PacketType.AUTH);
    } else if (this.challenge) {
      const str = "challenge rcon\n";
      const sendBuf = Buffer.alloc(str.length + 4);
      sendBuf.writeInt32LE(-1, 0);
      sendBuf.write(str, 4);
      this._sendSocket(sendBuf);
    } else {
      const sendBuf = Buffer.alloc(5);
      sendBuf.writeInt32LE(-1, 0);
      sendBuf.writeUInt8(0, 4);
      this._sendSocket(sendBuf);

      this.hasAuthed = true;
      this.emit("auth");
    }
  };

  public socketOnEnd = (): void => {
    this.emit("end");
    this.hasAuthed = false;
  };
}