Post scheduling (fixes #234)

crates/api_common/src/post.rs

@@ -30,6 +30,8 @@ pub struct CreatePost {
   pub language_id: Option<LanguageId>,
   /// Instead of fetching a thumbnail, use a custom one.
   pub custom_thumbnail: Option<String>,
+  /// Time when this post should be scheduled. Null means publish immediately.
+  pub scheduled_publish_time: Option<i64>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone)]
@@ -124,6 +126,8 @@ pub struct EditPost {
   pub language_id: Option<LanguageId>,
   /// Instead of fetching a thumbnail, use a custom one.
   pub custom_thumbnail: Option<String>,
+  /// Time when this post should be scheduled. Null means publish immediately.
+  pub scheduled_publish_time: Option<i64>,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Copy, Default, PartialEq, Eq, Hash)]

crates/api_common/src/utils.rs

@@ -220,7 +220,7 @@ async fn check_community_deleted_removed(
   Ok(())
 }
 
-async fn check_community_ban(
+pub async fn check_community_ban(
   person: &Person,
   community_id: CommunityId,
   pool: &mut DbPool<'_>,

crates/api_crud/Cargo.toml

@@ -27,6 +27,7 @@ futures.workspace = true
 uuid = { workspace = true }
 moka.workspace = true
 anyhow.workspace = true
+chrono.workspace = true
 webmention = "0.6.0"
 accept-language = "3.1.0"
 

crates/api_crud/src/post/create.rs

@@ -1,3 +1,4 @@
+use super::convert_published_time;
 use activitypub_federation::config::Data;
 use actix_web::web::Json;
 use lemmy_api_common::{
@@ -130,6 +131,8 @@ pub async fn create_post(
     }
   };
 
+  let scheduled_publish_time =
+    convert_published_time(data.scheduled_publish_time, &local_user_view, &context).await?;
   let post_form = PostInsertForm::builder()
     .name(data.name.trim().to_string())
     .url(url.map(Into::into))
@@ -139,16 +142,23 @@ pub async fn create_post(
     .creator_id(local_user_view.person.id)
     .nsfw(data.nsfw)
     .language_id(language_id)
+    .scheduled_publish_time(scheduled_publish_time)
     .build();
 
   let inserted_post = Post::create(&mut context.pool(), &post_form)
     .await
     .with_lemmy_type(LemmyErrorType::CouldntCreatePost)?;
 
+  let federate_post = if scheduled_publish_time.is_none() {
+    send_webmention(inserted_post.clone(), community);
+    |post| Some(SendActivityData::CreatePost(post))
+  } else {
+    |_| None
+  };
   generate_post_link_metadata(
     inserted_post.clone(),
     custom_thumbnail.map(Into::into),
-    |post| Some(SendActivityData::CreatePost(post)),
+    federate_post,
     context.reset_request_count(),
   )
   .await?;
@@ -168,11 +178,14 @@ pub async fn create_post(
 
   mark_post_as_read(person_id, post_id, &mut context.pool()).await?;
 
-  if let Some(url) = inserted_post.url.clone() {
+  build_post_response(&context, community_id, local_user_view, post_id).await
+}
+
+pub fn send_webmention(post: Post, community: Community) {
+  if let Some(url) = post.url.clone() {
     if community.visibility == CommunityVisibility::Public {
       spawn_try_task(async move {
-        let mut webmention =
-          Webmention::new::<Url>(inserted_post.ap_id.clone().into(), url.clone().into())?;
+        let mut webmention = Webmention::new::<Url>(post.ap_id.clone().into(), url.clone().into())?;
         webmention.set_checked(true);
         match webmention
           .send()
@@ -186,6 +199,4 @@ pub async fn create_post(
       });
     }
   };
-
-  build_post_response(&context, community_id, local_user_view, post_id).await
 }

crates/api_crud/src/post/mod.rs

@@ -1,5 +1,38 @@
+use chrono::{DateTime, TimeZone, Utc};
+use lemmy_api_common::context::LemmyContext;
+use lemmy_db_schema::source::post::Post;
+use lemmy_db_views::structs::LocalUserView;
+use lemmy_utils::{error::LemmyResult, LemmyErrorType};
+
 pub mod create;
 pub mod delete;
 pub mod read;
 pub mod remove;
 pub mod update;
+
+async fn convert_published_time(
+  scheduled_publish_time: Option<i64>,
+  local_user_view: &LocalUserView,
+  context: &LemmyContext,
+) -> LemmyResult<Option<DateTime<Utc>>> {
+  const MAX_SCHEDULED_POSTS: i64 = 10;
+  if let Some(scheduled_publish_time) = scheduled_publish_time {
+    let converted = Utc
+      .timestamp_opt(scheduled_publish_time, 0)
+      .single()
+      .ok_or(LemmyErrorType::InvalidUnixTime)?;
+    if converted < Utc::now() {
+      Err(LemmyErrorType::PostScheduleTimeMustBeInFuture)?;
+    }
+    if !local_user_view.local_user.admin {
+      let count =
+        Post::user_scheduled_post_count(local_user_view.person.id, &mut context.pool()).await?;
+      if count >= MAX_SCHEDULED_POSTS {
+        Err(LemmyErrorType::TooManyScheduledPosts)?;
+      }
+    }
+    Ok(Some(converted))
+  } else {
+    Ok(None)
+  }
+}

crates/api_crud/src/post/update.rs

@@ -1,3 +1,4 @@
+use super::{convert_published_time, create::send_webmention};
 use activitypub_federation::config::Data;
 use actix_web::web::Json;
 use lemmy_api_common::{
@@ -16,6 +17,7 @@ use lemmy_api_common::{
 use lemmy_db_schema::{
   source::{
     actor_language::CommunityLanguage,
+    community::Community,
     local_site::LocalSite,
     post::{Post, PostUpdateForm},
   },
@@ -109,6 +111,21 @@ pub async fn update_post(
   )
   .await?;
 
+  // handle changes to scheduled_publish_time
+  let scheduled_publish_time = match (
+    orig_post.scheduled_publish_time,
+    data.scheduled_publish_time,
+  ) {
+    // schedule time can be changed if post is still scheduled (and not published yet)
+    (Some(_), Some(_)) => {
+      Some(convert_published_time(data.scheduled_publish_time, &local_user_view, &context).await?)
+    }
+    // post was scheduled, gets changed to publish immediately
+    (Some(_), None) => Some(None),
+    // unchanged
+    (_, _) => None,
+  };
+
   let post_form = PostUpdateForm {
     name: data.name.clone(),
     url,
@@ -117,6 +134,7 @@ pub async fn update_post(
     nsfw: data.nsfw,
     language_id: data.language_id,
     updated: Some(Some(naive_now())),
+    scheduled_publish_time,
     ..Default::default()
   };
 
@@ -125,13 +143,38 @@ pub async fn update_post(
     .await
     .with_lemmy_type(LemmyErrorType::CouldntUpdatePost)?;
 
-  generate_post_link_metadata(
-    updated_post.clone(),
-    custom_thumbnail.flatten().map(Into::into),
-    |post| Some(SendActivityData::UpdatePost(post)),
-    context.reset_request_count(),
-  )
-  .await?;
+  // send out federation/webmention if necessary
+  match (
+    orig_post.scheduled_publish_time,
+    data.scheduled_publish_time,
+  ) {
+    // schedule was removed, send create activity and webmention
+    (Some(_), None) => {
+      let community = Community::read(&mut context.pool(), orig_post.community_id)
+        .await?
+        .ok_or(LemmyErrorType::CouldntFindPost)?;
+      send_webmention(updated_post.clone(), community);
+      generate_post_link_metadata(
+        updated_post.clone(),
+        custom_thumbnail.flatten().map(Into::into),
+        |post| Some(SendActivityData::CreatePost(post)),
+        context.reset_request_count(),
+      )
+      .await?;
+    }
+    // post was already public, send update
+    (None, _) => {
+      generate_post_link_metadata(
+        updated_post.clone(),
+        custom_thumbnail.flatten().map(Into::into),
+        |post| Some(SendActivityData::UpdatePost(post)),
+        context.reset_request_count(),
+      )
+      .await?
+    }
+    // schedule was changed, do nothing
+    (Some(_), Some(_)) => {}
+  };
 
   build_post_response(
     context.deref(),

crates/db_schema/src/impls/post.rs

@@ -1,7 +1,7 @@
 use crate::{
-  diesel::OptionalExtension,
+  diesel::{BoolExpressionMethods, OptionalExtension},
   newtypes::{CommunityId, DbUrl, PersonId, PostId},
-  schema::{post, post_hide, post_like, post_read, post_saved},
+  schema::{community, person, post, post_hide, post_like, post_read, post_saved},
   source::post::{
     Post,
     PostHide,
@@ -20,6 +20,7 @@ use crate::{
     functions::coalesce,
     get_conn,
     naive_now,
+    now,
     DbPool,
     DELETED_REPLACEMENT_TEXT,
     FETCH_LIMIT_MAX,
@@ -30,7 +31,7 @@ use crate::{
 use ::url::Url;
 use chrono::{DateTime, Utc};
 use diesel::{
-  dsl::insert_into,
+  dsl::{count, insert_into, not},
   result::Error,
   DecoratableTarget,
   ExpressionMethods,
@@ -169,6 +170,7 @@ impl Post {
     let object_id: DbUrl = object_id.into();
     post::table
       .filter(post::ap_id.eq(object_id))
+      .filter(post::scheduled_publish_time.is_null())
       .first(conn)
       .await
       .optional()
@@ -242,6 +244,28 @@ impl Post {
     .get_results::<Self>(conn)
     .await
   }
+
+  pub async fn user_scheduled_post_count(
+    person_id: PersonId,
+    pool: &mut DbPool<'_>,
+  ) -> Result<i64, Error> {
+    let conn = &mut get_conn(pool).await?;
+
+    post::table
+      .inner_join(person::table)
+      .inner_join(community::table)
+      // find all posts which have scheduled_publish_time that is in the  past
+      .filter(post::scheduled_publish_time.is_not_null())
+      .filter(coalesce(post::scheduled_publish_time, now()).lt(now()))
+      // make sure the post and community are still around
+      .filter(not(post::deleted.or(post::removed)))
+      .filter(not(community::removed.or(community::deleted)))
+      // only posts by specified user
+      .filter(post::creator_id.eq(person_id))
+      .select(count(post::id))
+      .first::<i64>(conn)
+      .await
+  }
 }
 
 #[async_trait]
@@ -456,6 +480,7 @@ mod tests {
       featured_community: false,
       featured_local: false,
       url_content_type: None,
+      scheduled_publish_time: None,
     };
 
     // Post Like

crates/db_schema/src/schema.rs

@@ -732,6 +732,7 @@ diesel::table! {
         featured_local -> Bool,
         url_content_type -> Nullable<Text>,
         alt_text -> Nullable<Text>,
+        scheduled_publish_time -> Nullable<Timestamptz>
     }
 }
 

crates/db_schema/src/source/post.rs

@@ -58,6 +58,8 @@ pub struct Post {
   pub url_content_type: Option<String>,
   /// An optional alt_text, usable for image posts.
   pub alt_text: Option<String>,
+  /// Time at which the post will be published. None means publish immediately.
+  pub scheduled_publish_time: Option<DateTime<Utc>>,
 }
 
 #[derive(Debug, Clone, TypedBuilder)]
@@ -90,6 +92,7 @@ pub struct PostInsertForm {
   pub featured_local: Option<bool>,
   pub url_content_type: Option<String>,
   pub alt_text: Option<String>,
+  pub scheduled_publish_time: Option<DateTime<Utc>>,
 }
 
 #[derive(Debug, Clone, Default)]
@@ -116,6 +119,7 @@ pub struct PostUpdateForm {
   pub featured_local: Option<bool>,
   pub url_content_type: Option<Option<String>>,
   pub alt_text: Option<Option<String>>,
+  pub scheduled_publish_time: Option<Option<DateTime<Utc>>>,
 }
 
 #[derive(PartialEq, Eq, Debug)]

crates/db_views/src/comment_view.rs

@@ -1083,6 +1083,7 @@ mod tests {
         featured_community: false,
         featured_local: false,
         url_content_type: None,
+        scheduled_publish_time: None,
       },
       community: Community {
         id: data.inserted_community.id,

crates/db_views/src/post_view.rs

@@ -317,11 +317,18 @@ fn queries<'a>() -> Queries<
     // hide posts from deleted communities
     query = query.filter(community::deleted.eq(false));
 
-    // only show deleted posts to creator
+    // only creator can see deleted posts and unpublished scheduled posts
     if let Some(person_id) = options.local_user.person_id() {
       query = query.filter(post::deleted.eq(false).or(post::creator_id.eq(person_id)));
+      query = query.filter(
+        post::scheduled_publish_time
+          .is_null()
+          .or(post::creator_id.eq(person_id)),
+      );
     } else {
-      query = query.filter(post::deleted.eq(false));
+      query = query
+        .filter(post::deleted.eq(false))
+        .filter(post::scheduled_publish_time.is_null());
     }
 
     // only show removed posts to admin when viewing user profile
@@ -1686,6 +1693,7 @@ mod tests {
         featured_community: false,
         featured_local: false,
         url_content_type: None,
+        scheduled_publish_time: None,
       },
       my_vote: None,
       unread_comments: 0,

crates/utils/src/error.rs

@@ -181,6 +181,8 @@ pub enum LemmyErrorType {
   Unknown(String),
   CantDeleteSite,
   UrlLengthOverflow,
+  PostScheduleTimeMustBeInFuture,
+  TooManyScheduledPosts,
 }
 
 cfg_if! {

migrations/2024-09-16-095656_schedule-post/down.sql

@@ -0,0 +1,3 @@
+ALTER TABLE post
+    DROP COLUMN scheduled_publish_time;
+

migrations/2024-09-16-095656_schedule-post/up.sql

@@ -0,0 +1,5 @@
+ALTER TABLE post
+    ADD COLUMN scheduled_publish_time timestamptz;
+
+CREATE INDEX idx_post_scheduled_publish_time ON post (scheduled_publish_time);
+