Integrate utterances comments

_includes/comments/disqus.html

@@ -0,0 +1,54 @@
+<!--
+  The Disqus lazy loading.
+-->
+<div id="disqus_thread" class="pt-2 pb-2">
+  <p class="text-center text-muted small">
+    Comments powered by <a href="https://disqus.com/">Disqus</a>.
+  </p>
+</div>
+
+<script type="text/javascript">
+
+  var disqus_config = function () {
+    this.page.url = '{{ page.url | absolute_url }}';
+    this.page.identifier = '{{ page.url }}';
+  };
+
+  /* Lazy loading */
+
+  var disqus_observer = new IntersectionObserver(function (entries) {
+    if(entries[0].isIntersecting) {
+        (function () {
+            var d = document, s = d.createElement('script');
+            s.src = 'https://{{ site.comments.disqus.shortname }}.disqus.com/embed.js';
+            s.setAttribute('data-timestamp', +new Date());
+            (d.head || d.body).appendChild(s);
+        })();
+
+        disqus_observer.disconnect();
+    }
+  }, { threshold: [0] });
+
+  disqus_observer.observe(document.querySelector('#disqus_thread'));
+
+  /* Auto switch theme */
+
+  function reloadDisqus() {
+    /* Disqus hasn't been loaded */
+    if (typeof DISQUS === "undefined") {
+      return;
+    }
+
+    if (document.readyState == 'complete') {
+      DISQUS.reset({ reload: true, config: disqus_config });
+    }
+  }
+
+  const modeToggle = document.querySelector(".mode-toggle");
+
+  if (typeof modeToggle !== "undefined") {
+    /*  modeToggle.addEventListener('click', reloadDisqus); // not pretty for 'color-scheme'  */
+    window.matchMedia('(prefers-color-scheme: dark)').addEventListener('change', reloadDisqus);
+  }
+
+</script>