From 5f7ff41ed96dd460e3d6ef8278d8e8723adab6c3 Mon Sep 17 00:00:00 2001
From: Kegan Dougal <kegan@matrix.org>
Date: Tue, 17 Mar 2020 16:43:45 +0000
Subject: [PATCH] refactor: split out grabbing state to reduce cyclo complexity

---
 roomserver/query/query.go | 56 +++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 26 deletions(-)

diff --git a/roomserver/query/query.go b/roomserver/query/query.go
index a73ce699d..2de8e0d08 100644
--- a/roomserver/query/query.go
+++ b/roomserver/query/query.go
@@ -637,12 +637,6 @@ func (r *RoomserverQueryAPI) QueryStateAndAuthChain(
 	request *api.QueryStateAndAuthChainRequest,
 	response *api.QueryStateAndAuthChainResponse,
 ) error {
-	// TODO: get the correct room version
-	roomState, err := state.GetStateResolutionAlgorithm(state.StateResolutionAlgorithmV1, r.DB)
-	if err != nil {
-		return err
-	}
-
 	response.QueryStateAndAuthChainRequest = *request
 	roomNID, err := r.DB.RoomNID(ctx, request.RoomID)
 	if err != nil {
@@ -653,30 +647,12 @@ func (r *RoomserverQueryAPI) QueryStateAndAuthChain(
 	}
 	response.RoomExists = true
 
-	prevStates, err := r.DB.StateAtEventIDs(ctx, request.PrevEventIDs)
+	stateEvents, err := r.loadStateAtEventIDs(ctx, request.PrevEventIDs)
 	if err != nil {
-		switch err.(type) {
-		case types.MissingEventError:
-			return nil
-		default:
-			return err
-		}
+		return err
 	}
 	response.PrevEventsExist = true
 
-	// Look up the currrent state for the requested tuples.
-	stateEntries, err := roomState.LoadCombinedStateAfterEvents(
-		ctx, prevStates,
-	)
-	if err != nil {
-		return err
-	}
-
-	stateEvents, err := r.loadStateEvents(ctx, stateEntries)
-	if err != nil {
-		return err
-	}
-
 	// add the auth event IDs for the current state events too
 	var authEventIDs []string
 	authEventIDs = append(authEventIDs, request.AuthEventIDs...)
@@ -707,6 +683,34 @@ func (r *RoomserverQueryAPI) QueryStateAndAuthChain(
 	return err
 }
 
+func (r *RoomserverQueryAPI) loadStateAtEventIDs(ctx context.Context, eventIDs []string) ([]gomatrixserverlib.Event, error) {
+	// TODO: get the correct room version
+	roomState, err := state.GetStateResolutionAlgorithm(state.StateResolutionAlgorithmV1, r.DB)
+	if err != nil {
+		return nil, err
+	}
+
+	prevStates, err := r.DB.StateAtEventIDs(ctx, eventIDs)
+	if err != nil {
+		switch err.(type) {
+		case types.MissingEventError:
+			return nil, nil
+		default:
+			return nil, err
+		}
+	}
+
+	// Look up the currrent state for the requested tuples.
+	stateEntries, err := roomState.LoadCombinedStateAfterEvents(
+		ctx, prevStates,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return r.loadStateEvents(ctx, stateEntries)
+}
+
 // getAuthChain fetches the auth chain for the given auth events. An auth chain
 // is the list of all events that are referenced in the auth_events section, and
 // all their auth_events, recursively. The returned set of events contain the