From 00a195f0b561e204d565e6ddd229fabe21c5ad39 Mon Sep 17 00:00:00 2001
From: Victor-AcostaCNC <victor.acosta@netcentric.biz>
Date: Tue, 3 Oct 2023 09:23:58 +0200
Subject: [PATCH] Fix #336-add animations on a Metadata level

---
 scripts/lib-franklin.js | 62 ++++++++++++++++++++++++++
 styles/styles.css       | 96 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 158 insertions(+)

diff --git a/scripts/lib-franklin.js b/scripts/lib-franklin.js
index 9a45d90..61c6780 100644
--- a/scripts/lib-franklin.js
+++ b/scripts/lib-franklin.js
@@ -316,6 +316,66 @@ export function readBlockConfig(block) {
   return config;
 }
 
+/**
+ * adds animation on metadata level
+ */
+export function addAnimation() {
+  const addClass = (elem, className) => {
+    elem.classList.add(className);
+  };
+
+  const animationTypeMeta = getMetadata('animation');
+
+  const elementsToAnimate = document.querySelectorAll('h1, h2, h3, h4, h5, h6, a, img');
+
+  const applyAnimation = (entries) => {
+    entries.forEach((entry) => {
+      if (entry.isIntersecting && entry.intersectionRatio >= 0.3) {
+        switch (animationTypeMeta) {
+          case 'up':
+            addClass(entry.target, 'animated-up');
+            break;
+          case 'down':
+            addClass(entry.target, 'animated-down');
+            break;
+          case 'left':
+            addClass(entry.target, 'animated-left');
+            break;
+          case 'right':
+            addClass(entry.target, 'animated-right');
+            break;
+          default:
+            break;
+        }
+        // eslint-disable-next-line no-use-before-define
+        observer.unobserve(entry.target); // Stop observing once animation is applied
+      }
+    });
+  };
+
+  const observer = new IntersectionObserver(applyAnimation, { threshold: 0.3 });
+
+  elementsToAnimate.forEach((element) => {
+    observer.observe(element);
+  });
+
+  // Observe the body for changes
+  const bodyObserver = new MutationObserver(() => {
+    elementsToAnimate.forEach((element) => {
+      observer.observe(element);
+    });
+  });
+
+  bodyObserver.observe(document.body, { childList: true, subtree: true });
+
+  // Observe the window for scrolling
+  window.addEventListener('scroll', () => {
+    elementsToAnimate.forEach((element) => {
+      observer.observe(element);
+    });
+  });
+}
+
 /**
  * Decorates all sections in a container element.
  * @param {Element} $main The container element
@@ -650,6 +710,8 @@ function init() {
   window.addEventListener('error', (event) => {
     sampleRUM('error', { source: event.filename, target: event.lineno });
   });
+
+  addAnimation();
 }
 
 init();
diff --git a/styles/styles.css b/styles/styles.css
index beb751c..958dff7 100644
--- a/styles/styles.css
+++ b/styles/styles.css
@@ -653,3 +653,99 @@ main .section.text-white {
   white-space: nowrap;
   width: 1px;
 }
+
+/* animations */
+
+@keyframes fade-in {
+  0% {
+    opacity: 0;
+  }
+
+  100% {
+    opacity: 1;
+  }
+}
+
+@keyframes animated-up {
+  0% {
+    opacity: 0;
+    transform: translateY(20px);
+  }
+
+  100% {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+@keyframes animated-down {
+  0% {
+    opacity: 0;
+    transform: translateY(-20px);
+  }
+
+  100% {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+@keyframes animated-right {
+  0% {
+    opacity: 0;
+    transform: translateX(-20px);
+  }
+
+  100% {
+    opacity: 1;
+    transform: translateX(0);
+  }
+}
+
+@keyframes animated-left {
+  0% {
+    opacity: 0;
+    transform: translateX(20px);
+  }
+
+  100% {
+    opacity: 1;
+    transform: translateX(0);
+  }
+}
+
+/* animations written on metadata level */
+
+.animated-up {
+  animation: animated-up 0.5s ease-in-out forwards;
+}
+
+.animated-down {
+  animation: animated-down 0.5s ease-in-out forwards;
+}
+
+.animated-right {
+  animation: animated-right 0.5s ease-in-out forwards;
+}
+
+.animated-left {
+  animation: animated-left 0.5s ease-in-out forwards;
+}
+
+/* animations written on section-metadata level */
+
+ .section-animated-up {
+  animation: animated-up 0.5s ease-in-out forwards;
+}
+
+  .section-animated-down {
+  animation: animated-down 0.5s ease-in-out forwards;
+}
+
+ .section-animated-right {
+  animation: animated-right 0.5s ease-in-out forwards;
+}
+
+ .section-animated-left {
+  animation: animated-left 0.5s ease-in-out forwards;
+}