Split the server into three crates (#56)

This will make it easier to build variations on the server, or embed it
into larger projects.

server/src/api/get_snapshot.rs

@@ -0,0 +1,115 @@
+use crate::api::{
+    client_id_header, failure_to_ise, ServerState, SNAPSHOT_CONTENT_TYPE, VERSION_ID_HEADER,
+};
+use actix_web::{error, get, web, HttpRequest, HttpResponse, Result};
+use std::sync::Arc;
+use taskchampion_sync_server_core::get_snapshot;
+
+/// Get a snapshot.
+///
+/// If a snapshot for this client exists, it is returned with content-type
+/// `application/vnd.taskchampion.snapshot`.  The `X-Version-Id` header contains the version of the
+/// snapshot.
+///
+/// If no snapshot exists, returns a 404 with no content.  Returns other 4xx or 5xx responses on
+/// other errors.
+#[get("/v1/client/snapshot")]
+pub(crate) async fn service(
+    req: HttpRequest,
+    server_state: web::Data<Arc<ServerState>>,
+) -> Result<HttpResponse> {
+    let mut txn = server_state.storage.txn().map_err(failure_to_ise)?;
+
+    let client_id = client_id_header(&req)?;
+
+    let client = txn
+        .get_client(client_id)
+        .map_err(failure_to_ise)?
+        .ok_or_else(|| error::ErrorNotFound("no such client"))?;
+
+    if let Some((version_id, data)) =
+        get_snapshot(txn, &server_state.config, client_id, client).map_err(failure_to_ise)?
+    {
+        Ok(HttpResponse::Ok()
+            .content_type(SNAPSHOT_CONTENT_TYPE)
+            .append_header((VERSION_ID_HEADER, version_id.to_string()))
+            .body(data))
+    } else {
+        Err(error::ErrorNotFound("no snapshot"))
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::api::CLIENT_ID_HEADER;
+    use crate::Server;
+    use actix_web::{http::StatusCode, test, App};
+    use chrono::{TimeZone, Utc};
+    use pretty_assertions::assert_eq;
+    use taskchampion_sync_server_core::{InMemoryStorage, Snapshot, Storage};
+    use uuid::Uuid;
+
+    #[actix_rt::test]
+    async fn test_not_found() {
+        let client_id = Uuid::new_v4();
+        let storage: Box<dyn Storage> = Box::new(InMemoryStorage::new());
+
+        // set up the storage contents..
+        {
+            let mut txn = storage.txn().unwrap();
+            txn.new_client(client_id, Uuid::new_v4()).unwrap();
+        }
+
+        let server = Server::new(Default::default(), storage);
+        let app = App::new().configure(|sc| server.config(sc));
+        let app = test::init_service(app).await;
+
+        let uri = "/v1/client/snapshot";
+        let req = test::TestRequest::get()
+            .uri(uri)
+            .append_header((CLIENT_ID_HEADER, client_id.to_string()))
+            .to_request();
+        let resp = test::call_service(&app, req).await;
+        assert_eq!(resp.status(), StatusCode::NOT_FOUND);
+    }
+
+    #[actix_rt::test]
+    async fn test_success() {
+        let client_id = Uuid::new_v4();
+        let version_id = Uuid::new_v4();
+        let snapshot_data = vec![1, 2, 3, 4];
+        let storage: Box<dyn Storage> = Box::new(InMemoryStorage::new());
+
+        // set up the storage contents..
+        {
+            let mut txn = storage.txn().unwrap();
+            txn.new_client(client_id, Uuid::new_v4()).unwrap();
+            txn.set_snapshot(
+                client_id,
+                Snapshot {
+                    version_id,
+                    versions_since: 3,
+                    timestamp: Utc.with_ymd_and_hms(2001, 9, 9, 1, 46, 40).unwrap(),
+                },
+                snapshot_data.clone(),
+            )
+            .unwrap();
+        }
+
+        let server = Server::new(Default::default(), storage);
+        let app = App::new().configure(|sc| server.config(sc));
+        let app = test::init_service(app).await;
+
+        let uri = "/v1/client/snapshot";
+        let req = test::TestRequest::get()
+            .uri(uri)
+            .append_header((CLIENT_ID_HEADER, client_id.to_string()))
+            .to_request();
+        let resp = test::call_service(&app, req).await;
+        assert_eq!(resp.status(), StatusCode::OK);
+
+        use actix_web::body::MessageBody;
+        let bytes = resp.into_body().try_into_bytes().unwrap();
+        assert_eq!(bytes.as_ref(), snapshot_data);
+    }
+}