add environment variables for default configuration

index.mjs

@@ -1,3 +1,4 @@
+import 'dotenv/config';
 import express from 'express';
 import fs from 'fs';
 import corsPassThru from './cors/index.mjs';
@@ -20,7 +21,39 @@ app.get('/playlist.json', playlist);
 // version
 const { version } = JSON.parse(fs.readFileSync('package.json'));
 
+// read and parse environment variables to append to the query string
+// use the permalink (share) button on the web app to generate a starting point for your configuration
+// then take each key/value in the querystring and append WSQS_ to the beginning, and then replace any
+// hyphens with underscores in the key name
+// environment variables are read from the command line and .env file via the dotenv package
+
+const qsVars = {};
+
+Object.entries(process.env).forEach(([key, value]) => {
+	// test for key matching pattern described above
+	if (key.match(/^WSQS_[A-Za-z0-9_]+$/)) {
+		// convert the key to a querystring formatted key
+		const formattedKey = key.replace(/^WSQS_/, '').replaceAll('_', '-');
+		qsVars[formattedKey] = value;
+	}
+});
+
+// single flag to determine if environment variables are present
+const hasQsVars = Object.entries(qsVars).length > 0;
+
+// turn the environment query string into search params
+const defaultSearchParams = (new URLSearchParams(qsVars)).toString();
+
 const index = (req, res) => {
+	// test for no query string in request and if environment query string values were provided
+	if (hasQsVars && Object.keys(req.query).length === 0) {
+		// redirect the user to the query-string appended url
+		const url = new URL(`${req.protocol}://${req.host}${req.url}`);
+		url.search = defaultSearchParams;
+		res.redirect(307, url.toString());
+		return;
+	}
+	// return the standard page
 	res.render('index', {
 		production: false,
 		version,