From 766993cebce40553fe3d90439efae53a798b66a8 Mon Sep 17 00:00:00 2001
From: Ole Eskild Steensen <ole@savvy.no>
Date: Mon, 19 Dec 2022 23:06:07 +0100
Subject: [PATCH] Implement link preview

---
 src/helpers/constants.js                      |   3 +-
 src/site/_includes/components/linkPreview.njk | 137 ++++++++++++++++++
 src/site/_includes/layouts/note.njk           |  12 +-
 src/site/index.njk                            |  11 +-
 src/site/styles/digital-garden-base.scss      |   5 +
 5 files changed, 159 insertions(+), 9 deletions(-)
 create mode 100644 src/site/_includes/components/linkPreview.njk

diff --git a/src/helpers/constants.js b/src/helpers/constants.js
index 110be22..dc6df6b 100644
--- a/src/helpers/constants.js
+++ b/src/helpers/constants.js
@@ -6,5 +6,6 @@ exports.ALL_NOTE_SETTINGS= [
     "dgShowInlineTitle",
     "dgShowFileTree",
     "dgEnableSearch",
-    "dgShowToc"
+    "dgShowToc",
+    "dgLinkPreview"
 ];
\ No newline at end of file
diff --git a/src/site/_includes/components/linkPreview.njk b/src/site/_includes/components/linkPreview.njk
new file mode 100644
index 0000000..ebdebf4
--- /dev/null
+++ b/src/site/_includes/components/linkPreview.njk
@@ -0,0 +1,137 @@
+<!-- All credit for this implementation goes to https://github.com/maximevaillancourt/digital-garden-jekyll-template/blob/master/_includes/link-previews.html -->
+<style>
+#tooltip-wrapper {
+  background: var(--background-primary);
+  padding: 1em;
+  border-radius: 4px;
+  overflow: hidden;
+  position: fixed;
+  width: 80%;
+  max-width: 400px;
+  height: auto;
+  max-height: 300px;
+  font-size: 0.8em;
+  box-shadow: 0 5px 10px rgba(0,0,0,0.1);
+  opacity: 0;
+  transition: opacity 100ms;
+  unicode-bidi: plaintext;
+  overflow-y: scroll;
+  z-index: 10;
+}
+
+#tooltip-wrapper:after {
+  content: "";
+  position: absolute;
+  z-index: 1;
+  bottom: 0;
+  left: 0;
+  pointer-events: none;
+  width: 100%;
+  unicode-bidi: plaintext;
+  height: 75px;
+}
+</style>
+<div style="opacity: 0; display: none;" id='tooltip-wrapper'>
+  <div id='tooltip-content'>
+  </div>
+</div>
+
+<iframe style="display: none; height: 0; width: 0;" id='link-preview-iframe' src="">
+</iframe>
+
+<script>
+  var opacityTimeout;
+  var contentTimeout;
+  var transitionDurationMs = 100;
+
+  var iframe = document.getElementById('link-preview-iframe')
+  var tooltipWrapper = document.getElementById('tooltip-wrapper')
+  var tooltipContent = document.getElementById('tooltip-content')
+
+  var linkHistories = {};
+
+  function hideTooltip() {
+    opacityTimeout = setTimeout(function () {
+      tooltipWrapper.style.opacity = 0;
+      contentTimeout = setTimeout(function () {
+        tooltipContent.innerHTML = '';
+        tooltipWrapper.style.display = 'none';
+      }, transitionDurationMs + 1);
+    }, transitionDurationMs)
+  }
+
+  function showTooltip(event) {
+    var elem = event.target;
+    var elem_props = elem.getClientRects()[elem.getClientRects().length - 1];
+    var top = window.pageYOffset || document.documentElement.scrollTop;
+    if (event.target.getAttribute("href").indexOf("http") === -1 || event.target.getAttribute("href").indexOf(window.location.host) !== -1) {
+      if (!linkHistories[event.target.getAttribute("href")]) {
+        iframe.src = event.target.getAttribute("href")
+        iframe.onload = function () {
+          tooltipContentHtml = ''
+          tooltipContentHtml += '<div style="font-weight: bold; unicode-bidi: plaintext;">' + iframe.contentWindow.document.querySelector('h1').innerHTML + '</div>'
+          tooltipContentHtml += iframe.contentWindow.document.querySelector('.content').innerHTML
+          tooltipContent.innerHTML = tooltipContentHtml
+          linkHistories[event.target.getAttribute("href")] = tooltipContentHtml
+          tooltipWrapper.style.display = 'block';
+          tooltipWrapper.scrollTop = 0;
+          setTimeout(function () {
+            tooltipWrapper.style.opacity = 1;
+          }, 1)
+        }
+      } else {
+        tooltipContent.innerHTML = linkHistories[event.target.getAttribute("href")]
+        tooltipWrapper.style.display = 'block';
+        setTimeout(function () {
+          tooltipWrapper.style.opacity = 1;
+        }, 1)
+      }
+
+      function getInnerWidth(elem) {
+        var style = window.getComputedStyle(elem);
+        return elem.offsetWidth - parseFloat(style.paddingLeft) - parseFloat(style.paddingRight) - parseFloat(style.borderLeft) - parseFloat(style.borderRight) - parseFloat(style.marginLeft) - parseFloat(style.marginRight);
+      }
+
+      tooltipWrapper.style.left = elem_props.left - (tooltipWrapper.offsetWidth / 2) + (elem_props.width / 2) + "px";
+
+      if ((window.innerHeight - elem_props.top) < (tooltipWrapper.offsetHeight)) {
+        tooltipWrapper.style.top = elem_props.top + top - tooltipWrapper.offsetHeight - 10 + "px";
+      } else if ((window.innerHeight - elem_props.top) > (tooltipWrapper.offsetHeight)) {
+        tooltipWrapper.style.top = elem_props.top + top + 35 + "px";
+      }
+
+      if ((elem_props.left + (elem_props.width / 2)) < (tooltipWrapper.offsetWidth / 2)) {
+        tooltipWrapper.style.left = "10px";
+      } else if ((document.body.clientWidth - elem_props.left - (elem_props.width / 2)) < (tooltipWrapper.offsetWidth / 2)) {
+        tooltipWrapper.style.left = document.body.clientWidth - tooltipWrapper.offsetWidth - 20 + "px";
+      }
+    }
+  }
+
+  function setupListeners(linkElement) {
+    linkElement.addEventListener('mouseleave', function (_event) {
+      hideTooltip();
+    });
+
+    tooltipWrapper.addEventListener('mouseleave', function (_event) {
+      hideTooltip();
+    });
+
+    linkElement.addEventListener('mouseenter', function (event) {
+      clearTimeout(opacityTimeout);
+      clearTimeout(contentTimeout);
+      showTooltip(event);
+    });
+
+    tooltipWrapper.addEventListener('mouseenter', function (event) {
+      clearTimeout(opacityTimeout);
+      clearTimeout(contentTimeout);
+    });
+  }
+
+  window.addEventListener("load", function(event) 
+  {
+    document.querySelectorAll('.internal-link').forEach(setupListeners);
+    document.querySelectorAll('.backlink-card a').forEach(setupListeners);
+  });
+</script>
diff --git a/src/site/_includes/layouts/note.njk b/src/site/_includes/layouts/note.njk
index 4c09231..8114454 100644
--- a/src/site/_includes/layouts/note.njk
+++ b/src/site/_includes/layouts/note.njk
@@ -26,10 +26,14 @@ permalink: "notes/{{ page.fileSlug | slugify }}/"
         <h1>{{ page.fileSlug }}</h1>
       {% endif %}
       {{ content | link | highlight | safe}}
-
-      {% if settings.dgShowBacklinks === true or settings.dgShowLocalGraph === true or settings.dgShowToc === true%}
-        {%include "components/sidebar.njk"%}
-      {% endif %}
     </div>
+
+    {% if settings.dgShowBacklinks === true or settings.dgShowLocalGraph === true or settings.dgShowToc === true%}
+      {%include "components/sidebar.njk"%}
+    {% endif %}
+
+    {% if settings.dgLinkPreview === true %}
+      {%include "components/linkPreview.njk"%}
+    {% endif %}
   </body>
 </html>
diff --git a/src/site/index.njk b/src/site/index.njk
index d2b1019..22f1447 100644
--- a/src/site/index.njk
+++ b/src/site/index.njk
@@ -22,11 +22,14 @@
       {%- for garden in collections.gardenEntry -%}
         {{garden.templateContent | link | highlight | safe }}
       {%- endfor -%}
+    </div>
 
+    {% if settings.dgShowBacklinks === true or settings.dgShowLocalGraph === true or settings.dgShowToc === true%}
+      {%include "components/sidebar.njk" %}
+    {%endif%}
 
-      {% if settings.dgShowBacklinks === true or settings.dgShowLocalGraph === true or settings.dgShowToc === true%}
-        {%include "components/sidebar.njk" %}
-      {%endif%}
-      </div>
+    {% if settings.dgLinkPreview === true %}
+      {%include "components/linkPreview.njk"%}
+    {% endif %}
     </body>
   </html>
diff --git a/src/site/styles/digital-garden-base.scss b/src/site/styles/digital-garden-base.scss
index b1f4a21..29bdf11 100644
--- a/src/site/styles/digital-garden-base.scss
+++ b/src/site/styles/digital-garden-base.scss
@@ -13,6 +13,7 @@ body {
     font-size: 22px;
     line-height: 1.5;
     margin-top: 90px;
+    position: relative;
 
     @media(max-width: 800px) {
         margin-top: 150px;
@@ -212,6 +213,8 @@ ul.task-list {
         transform: none;
         border-radius: 4px;
         margin-top: 50px;
+        max-width: 800px;
+        margin: auto;
     }
 
     .graph {
@@ -224,6 +227,8 @@ ul.task-list {
 
     .backlinks {
         margin-top: 0;
+        border-top: 3px solid var(--background-secondary); 
+        border-radius: 0;
     }
 }