Adding ability to specify a custom post thumbnail.

- Context: #4204

crates/api_common/src/post.rs

@@ -28,6 +28,8 @@ pub struct CreatePost {
   pub honeypot: Option<String>,
   pub nsfw: Option<bool>,
   pub language_id: Option<LanguageId>,
+  /// Instead of fetching a thumbnail, use a custom one.
+  pub custom_thumbnail: Option<Url>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
@@ -114,6 +116,8 @@ pub struct EditPost {
   pub body: Option<String>,
   pub nsfw: Option<bool>,
   pub language_id: Option<LanguageId>,
+  /// Instead of fetching a thumbnail, use a custom one.
+  pub custom_thumbnail: Option<Url>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Default)]

crates/api_crud/src/post/create.rs

@@ -87,6 +87,7 @@ pub async fn create_post(
   // Fetch post links and pictrs cached image
   let metadata = fetch_link_metadata_opt(url.as_ref(), true, &context).await;
   let url = proxy_image_link_opt_apub(url, &context).await?;
+  let thumbnail_url = data.custom_thumbnail.or(metadata.thumbnail);
 
   // Only need to check if language is allowed in case user set it explicitly. When using default
   // language, it already only returns allowed languages.
@@ -121,7 +122,7 @@ pub async fn create_post(
     .embed_description(metadata.opengraph_data.description)
     .embed_video_url(metadata.opengraph_data.embed_video_url)
     .language_id(language_id)
-    .thumbnail_url(metadata.thumbnail)
+    .thumbnail_url(thumbnail_url)
     .build();
 
   let inserted_post = Post::create(&mut context.pool(), &post_form)

crates/api_crud/src/post/update.rs

@@ -70,7 +70,7 @@ pub async fn update_post(
     Err(LemmyErrorType::NoPostEditAllowed)?
   }
 
-  // Fetch post links and Pictrs cached image if url was updated
+  // Fetch post links and thumbnail if url was updated
   let (embed_title, embed_description, embed_video_url, thumbnail_url) = match &url {
     Some(url) => {
       let metadata = fetch_link_metadata(url, true, &context).await?;
@@ -78,7 +78,7 @@ pub async fn update_post(
         Some(metadata.opengraph_data.title),
         Some(metadata.opengraph_data.description),
         Some(metadata.opengraph_data.embed_video_url),
-        Some(metadata.thumbnail),
+        Some(data.custom_thumbnail.or(metadata.thumbnail)),
       )
     }
     _ => Default::default(),