From 0a7f7dc716a25b1071bacc16cb91b31441174453 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Mon, 13 Jun 2022 10:16:30 +0100
Subject: [PATCH 1/2] Add `--difference` to `resolve-state` tool

---
 cmd/resolve-state/main.go | 54 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

diff --git a/cmd/resolve-state/main.go b/cmd/resolve-state/main.go
index 6ed6ebdb8..da0f70f01 100644
--- a/cmd/resolve-state/main.go
+++ b/cmd/resolve-state/main.go
@@ -28,7 +28,9 @@ import (
 
 var roomVersion = flag.String("roomversion", "5", "the room version to parse events as")
 var filterType = flag.String("filtertype", "", "the event types to filter on")
+var difference = flag.Bool("difference", false, "whether to calculate the difference between snapshots")
 
+// nolint:gocyclo
 func main() {
 	ctx := context.Background()
 	cfg := setup.ParseFlags(true)
@@ -64,6 +66,58 @@ func main() {
 		RoomVersion: gomatrixserverlib.RoomVersion(*roomVersion),
 	})
 
+	if *difference {
+		if len(snapshotNIDs) != 2 {
+			panic("need exactly two state snapshot NIDs to calculate difference")
+		}
+
+		removed, added, err := stateres.DifferenceBetweeenStateSnapshots(ctx, snapshotNIDs[0], snapshotNIDs[1])
+		if err != nil {
+			panic(err)
+		}
+
+		var eventNIDs []types.EventNID
+		for _, entry := range append(removed, added...) {
+			eventNIDs = append(eventNIDs, entry.EventNID)
+		}
+
+		eventEntries, err := roomserverDB.Events(ctx, eventNIDs)
+		if err != nil {
+			panic(err)
+		}
+
+		events := make(map[types.EventNID]*gomatrixserverlib.Event, len(eventEntries))
+		for _, entry := range eventEntries {
+			events[entry.EventNID] = entry.Event
+		}
+
+		if len(removed) > 0 {
+			fmt.Println("Removed:")
+			for _, r := range removed {
+				event := events[r.EventNID]
+				fmt.Println()
+				fmt.Printf("* %s %s %q\n", event.EventID(), event.Type(), *event.StateKey())
+				fmt.Printf("  %s\n", string(event.Content()))
+			}
+		}
+
+		if len(removed) > 0 && len(added) > 0 {
+			fmt.Println()
+		}
+
+		if len(added) > 0 {
+			fmt.Println("Added:")
+			for _, a := range added {
+				event := events[a.EventNID]
+				fmt.Println()
+				fmt.Printf("* %s %s %q\n", event.EventID(), event.Type(), *event.StateKey())
+				fmt.Printf("  %s\n", string(event.Content()))
+			}
+		}
+
+		return
+	}
+
 	var stateEntries []types.StateEntry
 	for _, snapshotNID := range snapshotNIDs {
 		var entries []types.StateEntry

From e1136f4d3e372f9c0b8a309a387193621a53ae6d Mon Sep 17 00:00:00 2001
From: Till Faelligen <davidf@element.io>
Date: Mon, 13 Jun 2022 11:46:59 +0200
Subject: [PATCH 2/2] Make the linter happy again

---
 cmd/resolve-state/main.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/cmd/resolve-state/main.go b/cmd/resolve-state/main.go
index da0f70f01..c02140003 100644
--- a/cmd/resolve-state/main.go
+++ b/cmd/resolve-state/main.go
@@ -38,6 +38,7 @@ func main() {
 		Type:  "std",
 		Level: "error",
 	})
+	cfg.ClientAPI.RegistrationDisabled = true
 	base := base.NewBaseDendrite(cfg, "ResolveState", base.DisableMetrics)
 	args := flag.Args()
 
@@ -70,8 +71,8 @@ func main() {
 		if len(snapshotNIDs) != 2 {
 			panic("need exactly two state snapshot NIDs to calculate difference")
 		}
-
-		removed, added, err := stateres.DifferenceBetweeenStateSnapshots(ctx, snapshotNIDs[0], snapshotNIDs[1])
+		var removed, added []types.StateEntry
+		removed, added, err = stateres.DifferenceBetweeenStateSnapshots(ctx, snapshotNIDs[0], snapshotNIDs[1])
 		if err != nil {
 			panic(err)
 		}
@@ -81,7 +82,8 @@ func main() {
 			eventNIDs = append(eventNIDs, entry.EventNID)
 		}
 
-		eventEntries, err := roomserverDB.Events(ctx, eventNIDs)
+		var eventEntries []types.Event
+		eventEntries, err = roomserverDB.Events(ctx, eventNIDs)
 		if err != nil {
 			panic(err)
 		}