feat: implement subscription changes GET request

bruno/Subscriptions API/Get subscriptions changes for device.bru

@@ -0,0 +1,20 @@
+meta {
+  name: Get subscriptions changes for device
+  type: http
+  seq: 5
+}
+
+get {
+  url: http://localhost:8080/api/2/subscriptions/:username/:device_id?since=1740430923
+  body: none
+  auth: inherit
+}
+
+params:query {
+  since: 1740430923
+}
+
+params:path {
+  username: test
+  device_id: test.json
+}

bruno/Subscriptions API/Upload subscription changes for device.bru

@@ -4,13 +4,20 @@ meta {
   seq: 4
 }
 
-get {
+post {
   url: http://localhost:8080/api/2/subscriptions/:username/:device_id
-  body: none
-  auth: none
+  body: json
+  auth: inherit
 }
 
 params:path {
-  username: 
-  device_id: 
+  username: test
+  device_id: test.json
+}
+
+body:json {
+  {
+    "add": ["test_add_1"],
+    "remove": ["test_remove_1", "test_add_2"]
+  }
 }

src/db/models/subscription.rs

@@ -200,4 +200,19 @@ impl Subscription {
             Ok(())
         })
     }
+
+    pub fn updated_since_for_device(
+        pool: &DbPool,
+        device_id: i64,
+        timestamp: i64,
+    ) -> DbResult<Vec<Self>> {
+        Ok(subscriptions::table
+            .select(Self::as_select())
+            .filter(
+                subscriptions::device_id
+                    .eq(device_id)
+                    .and(subscriptions::time_changed.ge(timestamp)),
+            )
+            .get_results(&mut pool.get()?)?)
+    }
 }

src/server/gpodder/advanced/subscriptions.rs

@@ -1,9 +1,10 @@
 use axum::{
-    extract::{Path, State},
+    extract::{Path, Query, State},
     middleware,
     routing::post,
     Extension, Json, Router,
 };
+use serde::Deserialize;
 
 use crate::{
     db,
@@ -12,7 +13,10 @@ use crate::{
         gpodder::{
             auth_middleware,
             format::{Format, StringWithFormat},
-            models::{DeviceType, SubscriptionChangeResponse, SubscriptionDelta},
+            models::{
+                DeviceType, SubscriptionChangeResponse, SubscriptionDelta,
+                SubscriptionDeltaResponse,
+            },
         },
         Context,
     },
@@ -20,7 +24,10 @@ use crate::{
 
 pub fn router(ctx: Context) -> Router<Context> {
     Router::new()
-        .route("/{username}/{id}", post(post_subscription_changes))
+        .route(
+            "/{username}/{id}",
+            post(post_subscription_changes).get(get_subscription_changes),
+        )
         .layer(middleware::from_fn_with_state(ctx.clone(), auth_middleware))
 }
 
@@ -70,3 +77,55 @@ pub async fn post_subscription_changes(
         update_urls: vec![],
     }))
 }
+
+#[derive(Deserialize)]
+pub struct SinceQuery {
+    #[serde(default)]
+    since: i64,
+}
+
+pub async fn get_subscription_changes(
+    State(ctx): State<Context>,
+    Path((username, id)): Path<(String, StringWithFormat)>,
+    Extension(user): Extension<db::User>,
+    Query(query): Query<SinceQuery>,
+) -> AppResult<Json<SubscriptionDeltaResponse>> {
+    if id.format != Format::Json {
+        return Err(AppError::NotFound);
+    }
+
+    if username != user.username {
+        return Err(AppError::BadRequest);
+    }
+
+    let subscriptions = tokio::task::spawn_blocking(move || {
+        let device =
+            db::Device::by_device_id(&ctx.pool, user.id, &id)?.ok_or(AppError::NotFound)?;
+
+        Ok::<_, AppError>(db::Subscription::updated_since_for_device(
+            &ctx.pool,
+            device.id,
+            query.since,
+        )?)
+    })
+    .await
+    .unwrap()?;
+
+    let mut delta = SubscriptionDeltaResponse::default();
+    delta.timestamp = query.since;
+
+    for sub in subscriptions.into_iter() {
+        if sub.deleted {
+            delta.remove.push(sub.url);
+        } else {
+            delta.add.push(sub.url);
+        }
+
+        delta.timestamp = delta.timestamp.max(sub.time_changed);
+    }
+
+    // Timestamp should reflect the events *after* the last seen change
+    delta.timestamp += 1;
+
+    Ok(Json(delta))
+}

src/server/gpodder/models.rs

@@ -56,6 +56,13 @@ pub struct SubscriptionDelta {
     pub remove: Vec<String>,
 }
 
+#[derive(Serialize, Default)]
+pub struct SubscriptionDeltaResponse {
+    pub add: Vec<String>,
+    pub remove: Vec<String>,
+    pub timestamp: i64,
+}
+
 #[derive(Serialize)]
 pub struct SubscriptionChangeResponse {
     pub timestamp: i64,