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#!/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=${num_connected})`);
socket.on("disconnect", () => {
num_connected--;
console.log(`disconnect id=${socket_id} (nc=${num_connected})`);
});
socket.on("new", string => {
const res = database.add_new(string);
if (res != null) socket.emit("error", res);
});
socket.on("set_votes", (string, votes) => {
const res = database.set_votes(string, votes);
if (res != null) socket.emit("error", res);
});
socket.on("delete", string =>{
const res = database.remove(string);
if (res != null) socket.emit("error", res);
});
socket.emit("init", database.get());
});
// ------------------------------
// setup
// ------------------------------
const server = httpServer.listen(PORT, () => {
const host = server.address().address;
const port = server.address().port;
console.log("Server listening at http://" + host + ":" + port);
});
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