Add SavedMessages channel type, add create DM.

src/routes/users/open_dm.rs

@@ -0,0 +1,53 @@
+use crate::database::entities::{Channel, User};
+use crate::database::guards::reference::Ref;
+use crate::util::result::{Error, Result};
+use crate::database::get_collection;
+use rocket_contrib::json::JsonValue;
+use mongodb::bson::doc;
+use ulid::Ulid;
+
+#[get("/<target>/dm")]
+pub async fn req(user: User, target: Ref) -> Result<JsonValue> {
+    let query = if user.id == target.id {
+        doc! {
+            "type": "SavedMessages",
+            "user": &user.id
+        }
+    } else {
+        doc! {
+            "type": "DirectMessage",
+            "recipients": {
+                "$all": [ &user.id, &target.id ]
+            }
+        }
+    };
+
+    let existing_channel = get_collection("channels")
+        .find_one(query, None)
+        .await
+        .map_err(|_| Error::DatabaseError { operation: "find_one", with: "channel" })?;
+
+    if let Some(doc) = existing_channel {
+        Ok(json!(doc))
+    } else {
+        let id = Ulid::new().to_string();
+        let channel = if user.id == target.id {
+            Channel::SavedMessages {
+                id,
+                user: user.id
+            }
+        } else {
+            Channel::DirectMessage {
+                id,
+                active: false,
+                recipients: vec! [
+                    user.id,
+                    target.id
+                ]
+            }
+        };
+
+        channel.save().await?;
+        Ok(json!(channel))
+    }
+}