Add API method for retrieving tag timeline

README.md

@@ -132,6 +132,7 @@ POST /api/v1/statuses/{status_id}/unfavourite
 POST /api/v1/statuses/{status_id}/reblog
 POST /api/v1/statuses/{status_id}/unreblog
 GET /api/v1/timelines/home
+GET /api/v1/timelines/tag/{hashtag}
 ```
 
 Additional methods:

docs/openapi.yaml

@@ -18,7 +18,7 @@ paths:
           description: Post does not belong to user
         404:
           description: Post not found
-  /api/v1/{status_id}/make_permanent:
+  /api/v1/statuses/{status_id}/make_permanent:
     post:
       summary: Save post to IPFS
       parameters:
@@ -38,7 +38,7 @@ paths:
           description: IPFS integration is not enabled
         422:
           description: Post already saved to IPFS
-  /api/v1/{status_id}/signature:
+  /api/v1/statuses/{status_id}/signature:
     get:
       summary: Sign post data with instance key
       parameters:
@@ -69,7 +69,7 @@ paths:
           description: Ethereum integration is not enabled
         422:
           description: Post is not saved to IPFS
-  /api/v1/{status_id}/token_minted:
+  /api/v1/statuses/{status_id}/token_minted:
     post:
       summary: Register transaction that mints a token
       parameters:
@@ -95,6 +95,40 @@ paths:
           description: Post not found
         422:
           description: Transaction already registered
+  /api/v1/timelines/tag/{hashtag}:
+    get:
+      summary: View public posts containing the given hashtag
+      parameters:
+        - name: hashtag
+          in: path
+          description: Hashtag name
+          required: true
+          schema:
+            type: string
+        - name: max_id
+          in: query
+          description: Return results older than this ID.
+          required: false
+          schema:
+            type: string
+            format: uuid
+        - name: limit
+          in: query
+          description: Maximum number of results to return.
+          required: false
+          schema:
+            type: integer
+            default: 20
+      responses:
+        200:
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                description: Post list
+                type: array
+                items:
+                  $ref: '#/components/schemas/Status'
 
 components:
   parameters:
@@ -113,6 +147,14 @@ components:
         id:
           type: string
           format: uuid
+        content:
+          description: HTML-encoded status content.
+          type: string
+        tags:
+          description: Hashtags used within the status content.
+          type: array
+          items:
+            $ref: '#/components/schemas/Tag'
         ipfs_cid:
           type: string
           nullable: true
@@ -121,3 +163,11 @@ components:
           type: string
           nullable: true
           example: '0x5fe80cdea7f...'
+    Tag:
+      type: object
+      properties:
+        name:
+          description: 'The value of the hashtag after the # sign.'
+          type: string
+        url:
+          description: A link to the hashtag on the instance.

src/mastodon_api/timelines/views.rs

@@ -11,7 +11,7 @@ use crate::models::posts::helpers::{
     get_actions_for_posts,
     get_reposted_posts,
 };
-use crate::models::posts::queries::get_home_timeline;
+use crate::models::posts::queries::{get_home_timeline, get_posts_by_tag};
 use super::types::TimelineQueryParams;
 
 #[get("/home")]
@@ -42,7 +42,42 @@ async fn home_timeline(
     Ok(HttpResponse::Ok().json(statuses))
 }
 
+#[get("/tag/{hashtag}")]
+async fn hashtag_timeline(
+    auth: Option<BearerAuth>,
+    config: web::Data<Config>,
+    db_pool: web::Data<Pool>,
+    web::Path(hashtag): web::Path<String>,
+    query_params: web::Query<TimelineQueryParams>,
+) -> Result<HttpResponse, HttpError> {
+    let db_client = &**get_database_client(&db_pool).await?;
+    let maybe_current_user = match auth {
+        Some(auth) => Some(get_current_user(db_client, auth.token()).await?),
+        None => None,
+    };
+    let mut posts = get_posts_by_tag(
+        db_client,
+        &hashtag,
+        query_params.max_id,
+        query_params.limit,
+    ).await?;
+    get_reposted_posts(db_client, posts.iter_mut().collect()).await?;
+    if let Some(user) = maybe_current_user {
+        get_actions_for_posts(
+            db_client,
+            &user.id,
+            posts.iter_mut().collect(),
+        ).await?;
+    };
+    let statuses: Vec<Status> = posts
+        .into_iter()
+        .map(|post| Status::from_post(post, &config.instance_url()))
+        .collect();
+    Ok(HttpResponse::Ok().json(statuses))
+}
+
 pub fn timeline_api_scope() -> Scope {
     web::scope("/api/v1/timelines")
         .service(home_timeline)
+        .service(hashtag_timeline)
 }

src/models/posts/queries.rs

@@ -329,6 +329,46 @@ pub async fn get_posts_by_author(
     Ok(posts)
 }
 
+pub async fn get_posts_by_tag(
+    db_client: &impl GenericClient,
+    tag_name: &str,
+    max_post_id: Option<Uuid>,
+    limit: i64,
+) -> Result<Vec<Post>, DatabaseError> {
+    let statement = format!(
+        "
+        SELECT
+            post, actor_profile,
+            {related_attachments},
+            {related_mentions},
+            {related_tags}
+        FROM post
+        JOIN actor_profile ON post.author_id = actor_profile.id
+        WHERE
+            post.visibility = {visibility_public}
+            AND EXISTS (
+                SELECT 1 FROM post_tag JOIN tag ON post_tag.tag_id = tag.id
+                WHERE post_tag.post_id = post.id AND tag.tag_name = $1
+            )
+            AND ($2::uuid IS NULL OR post.id < $2)
+        ORDER BY post.id DESC
+        LIMIT $3
+        ",
+        related_attachments=RELATED_ATTACHMENTS,
+        related_mentions=RELATED_MENTIONS,
+        related_tags=RELATED_TAGS,
+        visibility_public=i16::from(&Visibility::Public),
+    );
+    let rows = db_client.query(
+        statement.as_str(),
+        &[&tag_name.to_lowercase(), &max_post_id, &limit],
+    ).await?;
+    let posts: Vec<Post> = rows.iter()
+        .map(Post::try_from)
+        .collect::<Result<_, _>>()?;
+    Ok(posts)
+}
+
 pub async fn get_post_by_id(
     db_client: &impl GenericClient,
     post_id: &Uuid,