Support auto-redirection by <link>

src/_locales/en/messages.json

@@ -163,6 +163,10 @@
     "message": "Prevents the use of an extra tab and instead redirects the action on the main page.",
     "description": "This is an option shown in the add-on settings."
   },
+  "optionRedirectImmediately": {
+    "message": "Redirect immediately on page load, instead of on action.",
+    "description": "This is an option shown in the add-on settings."
+  },
   "translatorCredit": {
     "message": "This add-on has been translated into English by $TRANSLATORS$.",
     "description": "The credit text for the translator. See https://github.com/TinyWebEx/common/blob/master/CONTRIBUTING.md#translator-credit-inside-of-add-on for how to translate this.",

src/background/modules/ActivityPubRedirect.js

@@ -0,0 +1,46 @@
+import * as NetworkTools from "/common/modules/NetworkTools.js";
+import * as AddonSettings from "/common/modules/AddonSettings/AddonSettings.js";
+import { resolveActivityPubId } from "/common/modules/MastodonApi.js";
+
+/**
+ * Scrapes the ActivityPub <link> destination from the HTML page, if needed and exists.
+ *
+ * @param {number} tabId
+ * @param {URL} url
+ * @returns {Promise}
+ */
+export async function redirectByActivityPubLink(tabId, url) {
+    if (!tabId || !url) {
+        throw new Error("Needs a tab id and a page URL");
+    }
+
+    const [objectId] = await browser.tabs.executeScript(tabId, {
+        code: `document.querySelector("link[rel=alternate][type='application/activity+json']")?.href`,
+        runAt: "document_end",
+    });
+    if (!objectId) {
+        return;
+    }
+
+    const ownMastodon = await AddonSettings.get("ownMastodon");
+    if (ownMastodon.server === url.hostname) {
+        return;
+    }
+
+    const body = await resolveActivityPubId(ownMastodon.server, objectId);
+
+    const baseUrl = `https://${ownMastodon.server}`;
+    let homeUrl;
+    if (body.accounts[0]) {
+        homeUrl = new URL(`@${body.accounts[0].acct}`, baseUrl);
+    } else if (body.statuses[0]) {
+        homeUrl = new URL(
+            `@${body.statuses[0].account.acct}/${body.statuses[0].id}`,
+            baseUrl
+        );
+    } else {
+        return;
+    }
+
+    await NetworkTools.redirectToWebsite(homeUrl, tabId);
+}

src/background/modules/AutoRemoteFollow.js

@@ -15,6 +15,7 @@ import * as MisskeyDetect from "./Detect/Misskey.js";
 
 import * as NetworkTools from "/common/modules/NetworkTools.js";
 import * as MastodonRedirect from "./MastodonRedirect.js";
+import { redirectByActivityPubLink } from "./ActivityPubRedirect.js";
 
 import * as AddonSettings from "/common/modules/AddonSettings/AddonSettings.js";
 import * as MastodonHandleCheck from "/common/modules/MastodonHandle/ConfigCheck.js";
@@ -149,12 +150,18 @@ function getInteractionType(url) {
 
 /**
  * Handles changes to the URL of a tab.
- * 
+ *
  * @param {string} tabId
  * @param {Object} changeInfo
  * @returns {void}
  */
 async function onTabUpdate(tabId, changeInfo) {
+    // clear cache of settings
+    await AddonSettings.loadOptions();
+    if (await AddonSettings.get("redirectImmediately")) {
+        redirectByActivityPubLink(tabId, changeInfo.url);
+    }
+
     const ownMastodon = await AddonSettings.get("ownMastodon");
     const currentURL = new URL(changeInfo.url);
     if (ownMastodon.server !== currentURL.hostname){

src/common/modules/MastodonApi.js

@@ -99,3 +99,22 @@ export function getTootStatus(mastodonServer, localTootId) {
         return response.json();
     });
 }
+
+/**
+ * Resolves the ActivityPub object ID on a given server
+ *
+ * @param {string} mastodonServer
+ * @param {string} objectId
+ */
+export async function resolveActivityPubId(mastodonServer, objectId) {
+    const apiUrl = new URL("api/v2/search", `https://${mastodonServer}`);
+    apiUrl.searchParams.set("q", objectId);
+    apiUrl.searchParams.set("resolve", "true");
+
+    const response = await NetworkTools.fetch(apiUrl);
+    if (!response.ok) {
+        throw new MastodonApiError(mastodonServer, response, `Failed to resolve ${objectId}.`);
+    }
+
+    return await response.json();
+}

src/common/modules/data/DefaultSettings.js

@@ -6,5 +6,6 @@
 
 export const DEFAULT_SETTINGS = Object.freeze({
     ownMastodon: null,
-    redirectInMainWindow: false
+    redirectInMainWindow: false,
+    redirectImmediately: false,
 });

src/options/options.html

@@ -85,6 +85,10 @@
 						<img class="icon-dismiss invisible" src="/common/img/close.svg" width="24" height="24" tabindex="0" data-i18n data-i18n-aria-label="__MSG_dismissIconDescription__"></span>
 					</div>
 				</div>
+				<div class="line indent">
+					<input class="setting save-on-change" type="checkbox" id="redirectImmediately" name="redirectImmediately">
+					<label data-i18n="__MSG_optionRedirectImmediately__" for="redirectImmediately">Redirect immediately on page load, instead of on action.</label>
+				</div>
 			</li>
 		</ul>