feat(PostBlock): Implement New XKit migration

src/features/postblock/index.js

@@ -1,7 +1,7 @@
 import { dom } from '../../utils/dom.js';
-import { getTimelineItemWrapper, filterPostElements } from '../../utils/interface.js';
+import { filterPostElements, getTimelineItemWrapper } from '../../utils/interface.js';
 import { registerMeatballItem, unregisterMeatballItem } from '../../utils/meatballs.js';
-import { showModal, hideModal, modalCancelButton } from '../../utils/modals.js';
+import { hideModal, modalCancelButton, modalCompleteButton, showModal } from '../../utils/modals.js';
 import { onNewPosts, pageModifications } from '../../utils/mutations.js';
 import { timelineObject } from '../../utils/react_props.js';
 
@@ -56,12 +56,58 @@ export const onStorageChanged = async function (changes) {
   }
 };
 
+const migrateBlockedPosts = async ({ detail }) => {
+  const newBlockedPostRootIDs = JSON.parse(detail);
+
+  if (Array.isArray(newBlockedPostRootIDs)) {
+    window.dispatchEvent(new CustomEvent('xkit-postblock-migration-success'));
+
+    const toAdd = newBlockedPostRootIDs
+      .map(id => String(id))
+      .filter(id => !blockedPostRootIDs.includes(id));
+
+    if (toAdd.length) {
+      await new Promise(resolve => {
+        showModal({
+          title: 'Add blocked posts?',
+          message: [
+            `Would you like to import ${toAdd.length} blocked post id${
+              toAdd.length === 1 ? '' : 's'
+            } from New XKit to XKit Rewritten?`,
+          ],
+          buttons: [
+            modalCancelButton,
+            dom('button', { class: 'blue' }, { click: resolve }, ['Confirm']),
+          ],
+        });
+      });
+
+      blockedPostRootIDs.push(...toAdd);
+      await browser.storage.local.set({ [storageKey]: blockedPostRootIDs });
+
+      showModal({
+        title: 'Success',
+        message: `Imported ${toAdd.length > 1 ? `${toAdd.length} blocked posts` : 'a blocked post'}!`,
+        buttons: [modalCompleteButton],
+      });
+    } else {
+      showModal({
+        title: 'No new blocked posts!',
+        message: 'Your XKit Rewritten configuration has these posts blocked already.',
+        buttons: [modalCompleteButton],
+      });
+    }
+  }
+};
+
 export const main = async function () {
   ({ [storageKey]: blockedPostRootIDs = [] } = await browser.storage.local.get(storageKey));
 
   registerMeatballItem({ id: meatballButtonId, label: meatballButtonLabel, onclick: onButtonClicked });
 
   onNewPosts.addListener(processPosts);
+
+  window.addEventListener('xkit-postblock-migration', migrateBlockedPosts);
 };
 
 export const clean = async function () {