From 29765a96d22c68091eadc3cfa29a31390a36c889 Mon Sep 17 00:00:00 2001
From: Naomi Pentrel <5212232+npentrel@users.noreply.github.com>
Date: Thu, 14 Sep 2023 12:56:56 -0400
Subject: [PATCH] DOCS-792: Persist tab selection to local storage (#1825)

---
 layouts/shortcodes/tabs.html |   4 +-
 static/js/tabpane-persist.js | 109 +++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+), 2 deletions(-)
 create mode 100644 static/js/tabpane-persist.js

diff --git a/layouts/shortcodes/tabs.html b/layouts/shortcodes/tabs.html
index 4882c4b608..e2505add5c 100644
--- a/layouts/shortcodes/tabs.html
+++ b/layouts/shortcodes/tabs.html
@@ -7,9 +7,9 @@
 		{{- range $i, $e := $tabs -}}
 		{{- $id := printf "%s-%d" $tab_set_id $i -}}
 		{{- if (eq $i 0) -}}
-<li class="nav-item"><a data-toggle="tab" class="nav-link active" href="#{{ $id }}" role="tab" aria-controls="{{ $id }}" aria-selected="true">{{- trim .name " " -}}</a></li>
+<li class="nav-item"><a data-toggle="tab" class="nav-link active" data-td-tp-persist="{{- trim .name " " -}}" data-bs-toggle="tab" data-bs-target="#{{ $id }}" href="#{{ $id }}" role="tab" aria-controls="{{ $id }}" aria-selected="true">{{- trim .name " " -}}</a></li>
 		{{ else }}
-<li class="nav-item"><a data-toggle="tab" class="nav-link" href="#{{ $id }}" role="tab" aria-controls="{{ $id }}">{{- trim .name " " -}}</a></li>
+<li class="nav-item"><a data-toggle="tab" class="nav-link" data-td-tp-persist="{{- trim .name " " -}}" data-bs-toggle="tab" data-bs-target="#{{ $id }}" href="#{{ $id }}" role="tab" aria-controls="{{ $id }}">{{- trim .name " " -}}</a></li>
 		{{- end -}}
 		{{- end -}}
 </ul>
diff --git a/static/js/tabpane-persist.js b/static/js/tabpane-persist.js
new file mode 100644
index 0000000000..6256ffe90c
--- /dev/null
+++ b/static/js/tabpane-persist.js
@@ -0,0 +1,109 @@
+// Utilities
+const _tdStoragePersistKey = (tabKey) =>
+   'td-tp-persist:' + (tabKey || '');
+
+const _tdSupportsLocalStorage = () => typeof Storage !== 'undefined';
+
+// Helpers
+function tdPersistKey(key, value) {
+  // @requires: tdSupportsLocalStorage();
+    console.log("key", key, "value", value);
+  try {
+    if (value) {
+      localStorage.setItem(key, value);
+    } else {
+      localStorage.removeItem(key);
+    }
+  } catch (error) {
+    const action = value ? 'add' : 'remove';
+    console.error(
+      `Docsy tabpane: unable to ${action} localStorage key '${key}': `,
+      error
+    );
+  }
+}
+
+// Retrieve, increment, and store tab-select event count, then returns it.
+function tdGetTabSelectEventCountAndInc() {
+  // @requires: tdSupportsLocalStorage();
+
+  const storedCount = localStorage.getItem('td-tp-persist-count');
+  let numTabSelectEvents = parseInt(storedCount) || 0;
+  numTabSelectEvents++;
+  tdPersistKey('td-tp-persist-count', numTabSelectEvents.toString());
+  return numTabSelectEvents;
+}
+
+// Main functions
+
+function tdActivateTabsWithKey(key) {
+  console.log(key)
+
+  if (!key) return;
+
+  document.querySelectorAll(`.nav-tabs > .nav-item > a[data-td-tp-persist='${key}']`).forEach((element) => {
+    console.log(element)
+    new bootstrap.Tab(element).show();
+  });
+}
+
+function tdPersistActiveTab(activeTabKey) {
+  if (!_tdSupportsLocalStorage()) return;
+
+  tdPersistKey(
+    _tdStoragePersistKey(activeTabKey),
+    tdGetTabSelectEventCountAndInc()
+  );
+  tdActivateTabsWithKey(activeTabKey);
+}
+
+// Handlers
+
+function tdGetAndActivatePersistedTabs(tabs) {
+  // Get unique persistence keys of tabs in this page
+  var keyOfTabsInThisPage = [
+    ...new Set(
+      Array.from(tabs).map((el) => el.getAttribute("data-td-tp-persist"))
+    ),
+  ];
+
+  // Create a list of active tabs with their age:
+  let key_ageList = keyOfTabsInThisPage
+    // Map to [tab-key, last-activated-age]
+    .map((k) => [
+      k,
+      parseInt(localStorage.getItem(_tdStoragePersistKey(k))) || 0,
+    ])
+    // Exclude tabs that have never been activated
+    .filter(([k, v]) => v)
+    // Sort from oldest selected to most recently selected
+    .sort((a, b) => a[1] - b[1]);
+
+  // Activate tabs from the oldest to the newest
+  key_ageList.forEach(([key]) => {
+    tdActivateTabsWithKey(key);
+  });
+
+  return key_ageList;
+}
+
+function tdRegisterTabClickHandler(tabs) {
+  tabs.forEach((tab) => {
+    tab.addEventListener('click', () => {
+      const activeTabKey = tab.getAttribute("data-td-tp-persist");
+      console.log("!!", activeTabKey)
+      tdPersistActiveTab(activeTabKey);
+      tdActivateTabsWithKey(activeTabKey)
+    });
+  });
+}
+
+// Register listeners and activate tabs
+window.addEventListener('DOMContentLoaded', () => {
+  if (!_tdSupportsLocalStorage()) return;
+
+  var allTabsInThisPage = document.querySelectorAll(".nav-tabs > .nav-item > a");
+  console.log(allTabsInThisPage);
+  tdRegisterTabClickHandler(allTabsInThisPage);
+  tdGetAndActivatePersistedTabs(allTabsInThisPage);
+});
\ No newline at end of file