#!/usr/bin/env node
const express = require("express");
const http = require("http");
const socketio = require("socket.io");
const fs = require("fs");

const [DBFILE, PORT] = (() => {
  if (process.argv.length == 3) {
    return [process.argv[2], 8000];
  } else if (process.argv.length == 4) {
    return [process.argv[2], +process.argv[3]];
  } else {
    console.log("Usage: ./server.js <dbfile.txt> [port]");
    process.exit(1);
  }
})();

const app = express();
const httpServer = http.Server(app);
const io = socketio(httpServer);

const STATIC = __dirname + "/static";


// ------------------------------
//           "database"
// ------------------------------

class Database {
  #filename;
  #list;
  #lastbackup;

  constructor(filename) {
    this.#filename = filename;
    this.#list = JSON.parse(fs.readFileSync(this.#filename));
    this.#lastbackup = new Date();
  }

  add_new(string) {
    for (let i = 0; i < this.#list.length; i++) {
      if (this.#list[i][1] == string) {
        return "already existed";
      }
    }

    this.#list.push([0, string]);
    this.#sort();
    this.#persist();

    return null;
  }

  set_votes(string, votes) {
    for (let i = 0; i < this.#list.length; i++) {
      if (this.#list[i][1] == string) {
        this.#list[i][0] = votes;
        this.#sort();
        this.#persist();
        return null;
      }
    }

    return `'${string}' does not exist`;
  }

  remove(string) {
    for (let i = 0; i < this.#list.length; i++) {
      if (this.#list[i][1] == string) {
        this.#list.splice(i, 1);
        this.#persist();
        return null;
      }
    }

    return "does not exist";
  }

  get() {
    return this.#list;
  }

  #sort() {
    this.#list.sort((a, b) => {
      if (a[0] != b[0]) return b[0] - a[0];
      if (a[1] < b[1]) return -1;
      if (a[1] > b[1]) return 1;
      return 0;
    });
  }

  #persist() {
    fs.writeFile(this.#filename, JSON.stringify(this.#list), err => {
      if (err != null) {
        console.error("Error writing to file:", err);
        console.log(JSON.stringify(this.#list));
      }
    });

    const now = new Date();
    if (now - this.#lastbackup > 60 * 1000) {
      const dotidx = this.#filename.lastIndexOf(".");
      const bakfname =
        dotidx == -1
          ? this.#filename + now.getTime()
          : this.#filename.slice(0, dotidx) + "." + now.getTime() + this.#filename.slice(dotidx);
      fs.writeFile(bakfname, JSON.stringify(this.#list), err => {
        if (err != null) {
          console.error("Error copying to backup file:", err);
        } else {
          console.log(`Copied to ${bakfname}`);
        }
      });

      this.#lastbackup = now;
    }
  }
};

const database = new Database(DBFILE);


// ------------------------------
//         Express routes
// ------------------------------

app.use(express.static(STATIC));

app.get("/", (req, res) => {
    res.sendFile(STATIC + "/index.html");
});


// ------------------------------
//       socket.io bindings
// ------------------------------

let next_socket_id = 1;
let num_connected = 0;

io.on("connection", socket => {
  const socket_id = next_socket_id++;
  if (++num_connected >= 2) {
    socket.emit("alert", `You're user number ${num_connected}, multi-user settings will mess up!`);
  }
  console.log(`new socket connection id=${socket_id} (nc=${num_connected})`);

  let logged_in = false;

  socket.on("disconnect", () => {
    num_connected--;
    console.log(`disconnect id=${socket_id} (nc=${num_connected})`);
  });

  socket.on("login", pass => {
    if (pass == fs.readFileSync(__dirname + "/password.txt").toString().trim()) {
      console.log(`login id=${socket_id}`);
      logged_in = true;
      socket.emit("init", database.get());
    } else {
      socket.emit("unauth");
    }
  });

  socket.on("new", string => {
    if (!logged_in) { socket.emit("unauth"); return; }
    const res = database.add_new(string);
    if (res != null) socket.emit("error", res);
  });

  socket.on("set_votes", (string, votes) => {
    if (!logged_in) { socket.emit("unauth"); return; }
    const res = database.set_votes(string, votes);
    if (res != null) socket.emit("error", res);
  });

  socket.on("delete", string =>{
    if (!logged_in) { socket.emit("unauth"); return; }
    const res = database.remove(string);
    if (res != null) socket.emit("error", res);
  });
});


// ------------------------------
//             setup
// ------------------------------

const server = httpServer.listen(PORT, () => {
  let host = server.address().address;
  if (host == "::") host = "localhost";
  const port = server.address().port;
  console.log("Server listening at http://" + host + ":" + port);
});