Adding ability to specify a custom post thumbnail. (#4425)

* Adding ability to specify a custom post thumbnail.

- Context: #4204

* Fixing ts-rs serialization.

* Fixing conversion, adding checks.

* Proxying custom_thumbnail. Fixed logic for update.

* Only generate metadata thumbnail is theres no custom thumbnail.

crates/api_common/src/post.rs

@@ -28,6 +28,9 @@ pub struct CreatePost {
   pub honeypot: Option<String>,
   pub nsfw: Option<bool>,
   pub language_id: Option<LanguageId>,
+  #[cfg_attr(feature = "full", ts(type = "string"))]
+  /// Instead of fetching a thumbnail, use a custom one.
+  pub custom_thumbnail: Option<Url>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
@@ -114,6 +117,9 @@ pub struct EditPost {
   pub body: Option<String>,
   pub nsfw: Option<bool>,
   pub language_id: Option<LanguageId>,
+  #[cfg_attr(feature = "full", ts(type = "string"))]
+  /// Instead of fetching a thumbnail, use a custom one.
+  pub custom_thumbnail: Option<Url>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Copy, Default, PartialEq, Eq, Hash)]

crates/api_crud/src/post/create.rs

@@ -57,10 +57,12 @@ pub async fn create_post(
 
   let data_url = data.url.as_ref();
   let url = data_url.map(clean_url_params); // TODO no good way to handle a "clear"
+  let custom_thumbnail = data.custom_thumbnail.as_ref().map(clean_url_params);
 
   is_valid_post_title(&data.name)?;
   is_valid_body_field(&body, true)?;
-  check_url_scheme(&data.url)?;
+  check_url_scheme(&url)?;
+  check_url_scheme(&custom_thumbnail)?;
 
   check_community_user_action(
     &local_user_view.person,
@@ -84,9 +86,17 @@ pub async fn create_post(
     }
   }
 
+  // Only generate the thumbnail if there's no custom thumbnail provided,
+  // otherwise it will save it in pictrs
+  let generate_thumbnail = custom_thumbnail.is_none();
+
   // Fetch post links and pictrs cached image
-  let metadata = fetch_link_metadata_opt(url.as_ref(), true, &context).await;
+  let metadata = fetch_link_metadata_opt(url.as_ref(), generate_thumbnail, &context).await;
   let url = proxy_image_link_opt_apub(url, &context).await?;
+  let thumbnail_url = proxy_image_link_opt_apub(custom_thumbnail, &context)
+    .await?
+    .map(Into::into)
+    .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 +131,7 @@ 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

@@ -43,6 +43,7 @@ pub async fn update_post(
   // TODO No good way to handle a clear.
   // Issue link: https://github.com/LemmyNet/lemmy/issues/2287
   let url = data.url.as_ref().map(clean_url_params);
+  let custom_thumbnail = data.custom_thumbnail.as_ref().map(clean_url_params);
 
   let slur_regex = local_site_to_slur_regex(&local_site);
   check_slurs_opt(&data.name, &slur_regex)?;
@@ -53,7 +54,8 @@ pub async fn update_post(
   }
 
   is_valid_body_field(&body, true)?;
-  check_url_scheme(&data.url)?;
+  check_url_scheme(&url)?;
+  check_url_scheme(&custom_thumbnail)?;
 
   let post_id = data.post_id;
   let orig_post = Post::read(&mut context.pool(), post_id).await?;
@@ -70,10 +72,14 @@ pub async fn update_post(
     Err(LemmyErrorType::NoPostEditAllowed)?
   }
 
-  // Fetch post links and Pictrs cached image if url was updated
-  let (embed_title, embed_description, embed_video_url, thumbnail_url) = match &url {
+  // Fetch post links and thumbnail if url was updated
+  let (embed_title, embed_description, embed_video_url, metadata_thumbnail) = match &url {
     Some(url) => {
-      let metadata = fetch_link_metadata(url, true, &context).await?;
+      // Only generate the thumbnail if there's no custom thumbnail provided,
+      // otherwise it will save it in pictrs
+      let generate_thumbnail = custom_thumbnail.is_none();
+
+      let metadata = fetch_link_metadata(url, generate_thumbnail, &context).await?;
       (
         Some(metadata.opengraph_data.title),
         Some(metadata.opengraph_data.description),
@@ -83,11 +89,21 @@ pub async fn update_post(
     }
     _ => Default::default(),
   };
+
   let url = match url {
     Some(url) => Some(proxy_image_link_opt_apub(Some(url), &context).await?),
     _ => Default::default(),
   };
 
+  let custom_thumbnail = match custom_thumbnail {
+    Some(custom_thumbnail) => {
+      Some(proxy_image_link_opt_apub(Some(custom_thumbnail), &context).await?)
+    }
+    _ => Default::default(),
+  };
+
+  let thumbnail_url = custom_thumbnail.or(metadata_thumbnail);
+
   let language_id = data.language_id;
   CommunityLanguage::is_allowed_community_language(
     &mut context.pool(),