database/migrations/2024_01_01_000015_store_numeric_community_id_on_platform_channels.php

@@ -67,6 +67,9 @@ public function down(): void
         });
     }
 
+    /** @var array<string, array{api: LemmyApiService, token: string}> */
+    private array $sessions = [];
+
     private function resolve(object $channel): int
     {
         if (is_numeric($channel->channel_id)) {
@@ -79,21 +82,38 @@ private function resolve(object $channel): int
             throw new RuntimeException("Channel {$channel->id} has no platform instance; cannot resolve its community id.");
         }
 
-        $account = PlatformAccount::where('instance_url', $instance->url)
+        $session = $this->session($instance->url, $channel->channel_id);
+
+        return $session['api']->getCommunityId($channel->channel_id, $session['token']);
+    }
+
+    /**
+     * Lemmy rate-limits logins, so authenticate once per instance rather than
+     * once per channel.
+     *
+     * @return array{api: LemmyApiService, token: string}
+     */
+    private function session(string $url, string $community): array
+    {
+        if (isset($this->sessions[$url])) {
+            return $this->sessions[$url];
+        }
+
+        $account = PlatformAccount::where('instance_url', $url)
             ->where('is_active', true)
             ->first();
 
         if (! $account) {
-            throw new RuntimeException("No active account for {$instance->url}; cannot resolve community '{$channel->channel_id}'.");
+            throw new RuntimeException("No active account for {$url}; cannot resolve community '{$community}'.");
         }
 
-        $api = new LemmyApiService($instance->url);
+        $api = new LemmyApiService($url);
         $token = $api->login($account->username, $account->password);
 
         if (! $token) {
-            throw new RuntimeException("Could not authenticate against {$instance->url} to resolve community '{$channel->channel_id}'.");
+            throw new RuntimeException("Could not authenticate against {$url} to resolve community '{$community}'.");
         }
 
-        return $api->getCommunityId($channel->channel_id, $token);
+        return $this->sessions[$url] = ['api' => $api, 'token' => $token];
     }
 };