From 90537f9d120dde173c956a8cbca2e886c42f7365 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Mon, 22 Jul 2024 21:40:19 -0700
Subject: [PATCH] Fix not being able to resolve remote Mastodon posts

Closes #515
---
 .../ConversationViewController.swift          | 21 ++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/Tusker/Screens/Conversation/ConversationViewController.swift b/Tusker/Screens/Conversation/ConversationViewController.swift
index dde6534d45..5b00a9d5e7 100644
--- a/Tusker/Screens/Conversation/ConversationViewController.swift
+++ b/Tusker/Screens/Conversation/ConversationViewController.swift
@@ -221,10 +221,16 @@ class ConversationViewController: UIViewController {
                 completionHandler(nil)
             }
         }
-        if isLikelyMastodonRemoteStatus(url: url),
-           let (_, response) = try? await URLSession.appDefault.data(from: url, delegate: RedirectBlocker()),
-           let location = (response as? HTTPURLResponse)?.value(forHTTPHeaderField: "location") {
-            effectiveURL = location
+        if isLikelyMastodonRemoteStatus(url: url) {
+            var request = URLRequest(url: url)
+            // Mastodon uses an intermediate redirect page for browsers which requires user input that we don't want.
+            request.addValue("application/activity+json", forHTTPHeaderField: "accept")
+            if let (_, response) = try? await URLSession.appDefault.data(for: request, delegate: RedirectBlocker()),
+              let location = (response as? HTTPURLResponse)?.value(forHTTPHeaderField: "location") {
+               effectiveURL = location
+           } else {
+               effectiveURL = WebURL(url)!.serialized(excludingFragment: true)
+           }
         } else {
             effectiveURL = WebURL(url)!.serialized(excludingFragment: true)
         }
@@ -232,9 +238,14 @@ class ConversationViewController: UIViewController {
         let request = Client.search(query: effectiveURL, types: [.statuses], resolve: true)
         do {
             let (results, _) = try await mastodonController.run(request)
-            guard let status = results.statuses.compactMap(\.value).first(where: { $0.url?.serialized() == effectiveURL }) else {
+            let statuses = results.statuses.compactMap(\.value)
+            // Don't try to exactly match effective URL because the URL form Mastodon
+            // uses for the ActivityPub redirect doesn't match what's returned by the API.
+            // Instead we just assume that, if only one status was returned, it worked.
+            guard statuses.count == 1 else {
                 throw UnableToResolveError()
             }
+            let status = statuses[0]
             _ = mastodonController.persistentContainer.addOrUpdateOnViewContext(status: status)
             mode = .localID(status.id)
             return status.id