Animate avatar GIFs on-hover on public profiles (#10549)

* Third time is the charm?

* Use full asset URL for data-static and data-original

̀image_tag` expands to the full asset URL, we have to do the same in `data` attributes so that it can work when assets and user data are stored on a different host

app/javascript/packs/public.js

@@ -173,6 +173,21 @@ function main() {
     avatar.src = url;
   });
 
+  const getProfileAvatarAnimationHandler = (swapTo) => {
+    //animate avatar gifs on the profile page when moused over
+    return ({ target }) => {
+      const swapSrc = target.getAttribute(swapTo);
+      //only change the img source if autoplay is off and the image src is actually different
+      if(target.getAttribute('data-autoplay') === 'false' && target.src !== swapSrc) {
+        target.src = swapSrc;
+      }
+    };
+  };
+
+  delegate(document, 'img#profile_page_avatar', 'mouseover', getProfileAvatarAnimationHandler('data-original'));
+
+  delegate(document, 'img#profile_page_avatar', 'mouseout', getProfileAvatarAnimationHandler('data-static'));
+
   delegate(document, '#account_header', 'change', ({ target }) => {
     const header = document.querySelector('.card .card__img img');
     const [file] = target.files || [];

app/views/accounts/_header.html.haml

@@ -3,7 +3,7 @@
     = image_tag (current_account&.user&.setting_auto_play_gif ? account.header_original_url : account.header_static_url), class: 'parallax'
   .public-account-header__bar
     = link_to short_account_url(account), class: 'avatar' do
-      = image_tag (current_account&.user&.setting_auto_play_gif ? account.avatar_original_url : account.avatar_static_url)
+      = image_tag (current_account&.user&.setting_auto_play_gif ? account.avatar_original_url : account.avatar_static_url), id: 'profile_page_avatar', data: {original: full_asset_url(account.avatar_original_url), static: full_asset_url(account.avatar_static_url), autoplay: current_account&.user&.setting_auto_play_gif}
     .public-account-header__tabs
       .public-account-header__tabs__name
         %h1