randomise background if no album cover exists

pages/index.php

@@ -7,6 +7,16 @@ if($reqPath === '/about' || $reqPath === '/about.html' || $reqPath === '/about.p
     return FM_HIT | 302;
 }
 
+if($reqPath === '/header-bgs.json') {
+    if($reqMethod !== 'GET')
+        return FM_ERR | 405;
+
+    header('Content-Type: application/json; charset=utf-8');
+    echo json_encode(FM_BGS);
+
+    return FM_HIT;
+}
+
 if($reqPath === '/now-listening') {
     if($reqMethod !== 'GET')
         return FM_ERR | 405;

public/assets/2020v2.js

@@ -6,6 +6,26 @@ window.fm = (function() {
     this.indexPlayingCover = null;
     this.indexPlayingTitle = null;
     this.indexPlayingArtist = null;
+    this.indexLastNp = null;
+
+    if(sessionStorage.getItem('header-bgs') === null
+        || sessionStorage.getItem('header-bgs-loaded') < Date.now() - 86400000) {
+        var hXhr = new XMLHttpRequest;
+        hXhr.onload = function() {
+            console.log(JSON.parse(hXhr.responseText));
+            sessionStorage.setItem('header-bgs', hXhr.responseText);
+            sessionStorage.setItem('header-bgs-loaded', Date.now());
+        };
+        hXhr.open('GET', '/header-bgs.json');
+        hXhr.send();
+    }
+
+    this.getRandomHeaderBackground = function() {
+        var set = JSON.parse(sessionStorage.getItem('header-bgs'));
+        if(!set)
+            return '/assets/errors/404.jpg';
+        return set[parseInt(Math.random() * set.length) - 1];
+    };
 
     this.selectTextInElement = function(elem) {
         // MSIE
@@ -53,6 +73,14 @@ window.fm = (function() {
 
     this.updateIndexNowListening = function() {
         window.fm.getNowListening(function(info) {
+            if(this.indexLastNp === null
+                || this.indexLastNp.url != info.url
+                || this.indexLastNp.now_playing != info.now_playing) {
+                if(this.indexLastNp !== null)
+                    this.originalHeaderBackground = this.getRandomHeaderBackground();
+                this.indexLastNp = info;
+            } else return;
+
             this.indexPlayingContainer.classList[info.now_playing ? 'remove' : 'add']('header-now-playing-hidden');
             this.indexPlayingCover.alt = this.indexPlayingCover.src = (info.cover !== this.defaultCoverImage ? info.cover : '//now.flash.moe/resources/no-cover.png');
             this.indexPlayingTitle.textContent = this.indexPlayingTitle.title = info.name;