feat(task_queue): web push task

closes #113

src/task_queue/task_web_push.rs

@@ -0,0 +1,67 @@
+// Queue Type: Linear
+use async_channel::{ Sender, Receiver, bounded };
+use mongodb::bson::{doc};
+use web_push::{ContentEncoding, SubscriptionInfo, SubscriptionKeys, VapidSignatureBuilder, WebPushClient, WebPushMessageBuilder};
+use rauth::entities::{Model, Session};
+use futures::StreamExt;
+
+use crate::util::variables::VAPID_PRIVATE_KEY;
+use crate::database::*;
+
+type Message = (Vec<String>, String);
+
+lazy_static! {
+    static ref CHANNEL: (Sender<Message>, Receiver<Message>) = bounded(100);
+}
+
+pub async fn queue(recipients: Vec<String>, payload: String) {
+    CHANNEL.0.send((recipients, payload)).await.ok();
+}
+
+pub async fn run() {
+    let client = WebPushClient::new();
+    let key = base64::decode_config(VAPID_PRIVATE_KEY.clone(), base64::URL_SAFE)
+        .expect("valid `VAPID_PRIVATE_KEY`");
+
+    while let Ok((recipients, payload)) = CHANNEL.1.recv().await {
+        if let Ok(mut cursor) = Session::find(
+            &get_db(),
+            doc! {
+                "_id": {
+                    "$in": recipients
+                },
+                "subscription": {
+                    "$exists": true
+                }
+            },
+            None
+        )
+        .await {
+            while let Some(Ok(session)) = cursor.next().await {
+                if let Some(sub) = session.subscription {
+                    let subscription = SubscriptionInfo {
+                        endpoint: sub.endpoint,
+                        keys: SubscriptionKeys {
+                            auth: sub.auth,
+                            p256dh: sub.p256dh
+                        }
+                    };
+
+                    let mut builder = WebPushMessageBuilder::new(&subscription).unwrap();
+                    let sig_builder = VapidSignatureBuilder::from_pem(
+                        std::io::Cursor::new(&key),
+                        &subscription,
+                    )
+                    .unwrap();
+
+                    let signature = sig_builder.build().unwrap();
+                    builder.set_vapid_signature(signature);
+                    builder.set_payload(ContentEncoding::AesGcm, payload.as_bytes());
+
+                    let msg = builder.build().unwrap();
+                    client.send(msg).await.ok();
+                }
+            }
+        }
+    }
+}