Added authentication

.gitignore

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+.idea/
+node_modules/
+bin/

package.json

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+{
+  "name": "spotify-local",
+  "version": "1.0.0",
+  "description": "",
+  "bin": "src/index.js",
+  "main": "src/index.js",
+  "scripts": {
+    "build": "pkg package.json"
+  },
+  "pkg": {
+    "scripts": "src/**/*.js",
+    "targets": [
+      "node18-linux-x64",
+      "node18-macos-x64",
+      "node18-win-x64"
+    ],
+    "outputPath": "bin"
+  },
+  "author": "Ian Wijma",
+  "license": "ISC",
+  "dependencies": {
+    "@inquirer/prompts": "^3.2.0",
+    "express": "^4.18.2",
+    "nanoid": "^3.3.6",
+    "pkg": "^5.8.1",
+    "yargs": "^17.7.2"
+  },
+  "devDependencies": {
+    "@types/node": "^20.8.10",
+    "@types/yargs": "^17.0.29"
+  }
+}

src/commands/authenticate.js

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+const {findAvailablePort} = require("../utilities/findAvailablePort");
+const {input} = require("@inquirer/prompts");
+const querystring = require("querystring");
+const {nanoid} = require("nanoid");
+const express = require('express')
+const {setAuth, hasAuth, authFile} = require("../utilities/authentication");
+
+exports.command = 'authenticate'
+exports.description = 'starts the Spotity authentication process'
+exports.builder = function (argv) {
+    return argv.option('client-id')
+}
+;
+exports.handler = async function (argv) {
+    if (hasAuth()) {
+        console.log(`spotify.local is already authenticated, remove "${authFile}" is you want to log out.`);
+        return;
+    }
+
+    const port = await findAvailablePort();
+
+    const authenticateRoute = 'authenticate';
+    const authenticateUrl = `http://localhost:${port}/${authenticateRoute}`;
+
+    const tutorial = [
+        'Visit https://developer.spotify.com/dashboard and click "Create app"',
+        'Set the "App name" as "spotify.local"',
+        'Set the "App description" as "My spotify.local"',
+        'Set the "Website" as "https://code.tmp.dev/ian/spotify.local"',
+        `Set the "Redirect URI" as "${authenticateUrl}"`,
+        'Select under "Which API/SDKs are you planning to use?" the "Web API"',
+        'Sign your life away by agreeing with the "Developer Terms of Service and Design Guidelines"',
+        'Click on the "Save" button',
+        'Copy the "Client ID" from the settings page',
+    ];
+
+    tutorial.forEach((string, index) => console.log(`${index+1} ${string}`));
+
+    const clientId = argv.clientId ?? await input({ message: `${tutorial.length}. Paste the clientId here` })
+    const originalState = nanoid();
+    const redirectUrl = new URL('https://accounts.spotify.com/authorize');
+    redirectUrl.search = querystring.stringify({
+        response_type: 'code',
+        client_id: clientId,
+        scope: [
+            'user-library-read',
+            'user-read-private',
+            'user-library-modify',
+            'user-follow-modify',
+            'user-follow-read',
+            'playlist-read-private',
+            'playlist-modify-public',
+            'playlist-modify-private',
+            'playlist-read-collaborative',
+            'user-top-read',
+            'user-read-recently-played',
+            'user-read-playback-state',
+            'user-modify-playback-state',
+            'user-read-currently-playing',
+            'user-read-playback-position'
+        ].join(' '),
+        redirect_uri: authenticateUrl,
+        state:  originalState
+    });
+
+    const app = express();
+
+    let server;
+    app.get(`/${authenticateRoute}`, (req, res) => {
+        const {state, code} = req.query;
+        if (originalState === state) {
+            setAuth(code);
+
+            res.send('<script>(() => close())()</script>');
+
+            server?.close();
+
+            console.log(`${tutorial.length+2}. Spotify.local has been authenticated`);
+        } else {
+            res.status(400);
+            res.send('NO')
+        }
+    });
+
+    server = app.listen(port, () => console.log(`${tutorial.length+1}. Follow the following URL to authenticate: ${redirectUrl}`));
+}

src/index.js

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+const Yargs = require('yargs');
+
+Yargs(process.argv.splice(2))
+    .commandDir('commands')
+    .demandCommand()
+    .help()
+    .argv;

src/utilities/authentication.js

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+const { existsSync, mkdirSync, writeFileSync, readFileSync } = require('fs');
+const { homedir } = require('os');
+
+const configDir = `${homedir()}/.spotify-local`
+const authenticationFile = `${configDir}/authentication`
+
+const ensure = () => {
+    if (!existsSync(configDir)) mkdirSync(configDir);
+    if (!existsSync(authenticationFile)) writeFileSync(authenticationFile, '');
+    return true;
+};
+
+exports.authFile = authenticationFile;
+exports.setAuth = (code) => ensure() && writeFileSync(authenticationFile, code);
+exports.getAuth = () => ensure() && readFileSync(authenticationFile).toString();
+exports.hasAuth = () => ensure() && readFileSync(authenticationFile).toString() !== '';

src/utilities/findAvailablePort.js

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+const net = require('net');
+
+const startPort = 5000;
+const endPort = 10000;
+
+const portAvailable = (port) => new Promise((resolve, reject) => {
+    const server = net.createServer();
+
+    server.once('error', function(err) {
+        if (err.code === 'EADDRINUSE') {
+            reject([null, false])
+        }
+
+        reject([err])
+    });
+
+    server.once('listening', function() {
+        server.close();
+        resolve([null, true])
+    });
+
+    console.log(`Checking port ${port}`);
+
+    server.listen(port);
+});
+
+/**
+ * @returns {Promise<number>}
+ */
+exports.findAvailablePort = async function () {
+    for (let port = startPort; startPort <= endPort; port++) {
+        const [error, available] = await portAvailable(port);
+        if (error) throw error;
+        if (available) return port;
+    }
+}