refactor sync server into modules

sync-server/src/api/get_child_version.rs

@@ -0,0 +1,19 @@
+use crate::server::SyncServer;
+use crate::types::{ClientId, VersionId};
+use actix_web::{error, get, http::StatusCode, web, HttpResponse, Result};
+use std::sync::Arc;
+
+#[get("/client/{client_id}/get-child-version/{parent_version_id}")]
+pub(crate) async fn service(
+    data: web::Data<Arc<SyncServer>>,
+    web::Path((client_id, parent_version_id)): web::Path<(ClientId, VersionId)>,
+) -> Result<HttpResponse> {
+    let result = data
+        .get_child_version(client_id, parent_version_id)
+        .map_err(|e| error::InternalError::new(e, StatusCode::INTERNAL_SERVER_ERROR))?;
+    if let Some(result) = result {
+        Ok(HttpResponse::Ok().json(result))
+    } else {
+        Err(error::ErrorNotFound("no such version"))
+    }
+}