From 172ce83318a4d4d14249891ef9d4c036c6122d8a Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Wed, 19 Apr 2023 17:26:21 +0300
Subject: [PATCH] Add option to disable reply fallbacks

---
 config/bridge.go    | 1 +
 config/upgrade.go   | 1 +
 example-config.yaml | 3 +++
 portal.go           | 5 ++++-
 4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/config/bridge.go b/config/bridge.go
index 3046d92..6f3d75f 100644
--- a/config/bridge.go
+++ b/config/bridge.go
@@ -118,6 +118,7 @@ type BridgeConfig struct {
 	CaptionInMessage      bool   `yaml:"caption_in_message"`
 	ExtEvPolls            bool   `yaml:"extev_polls"`
 	CrossRoomReplies      bool   `yaml:"cross_room_replies"`
+	DisableReplyFallbacks bool   `yaml:"disable_reply_fallbacks"`
 
 	MessageHandlingTimeout struct {
 		ErrorAfterStr string `yaml:"error_after"`
diff --git a/config/upgrade.go b/config/upgrade.go
index 4a137e6..32ba458 100644
--- a/config/upgrade.go
+++ b/config/upgrade.go
@@ -115,6 +115,7 @@ func DoUpgrade(helper *up.Helper) {
 		helper.Copy(up.Bool, "bridge", "extev_polls")
 	}
 	helper.Copy(up.Bool, "bridge", "cross_room_replies")
+	helper.Copy(up.Bool, "bridge", "disable_reply_fallbacks")
 	helper.Copy(up.Str|up.Null, "bridge", "message_handling_timeout", "error_after")
 	helper.Copy(up.Str|up.Null, "bridge", "message_handling_timeout", "deadline")
 
diff --git a/example-config.yaml b/example-config.yaml
index 93f1eb8..a636e58 100644
--- a/example-config.yaml
+++ b/example-config.yaml
@@ -313,6 +313,9 @@ bridge:
     extev_polls: false
     # Should cross-chat replies from WhatsApp be bridged? Most servers and clients don't support this.
     cross_room_replies: false
+    # Disable generating reply fallbacks? Some extremely bad clients still rely on them,
+    # but they're being phased out and will be completely removed in the future.
+    disable_reply_fallbacks: false
     # Maximum time for handling Matrix events. Duration strings formatted for https://pkg.go.dev/time#ParseDuration
     # Null means there's no enforced timeout.
     message_handling_timeout:
diff --git a/portal.go b/portal.go
index 4d3acf1..277a757 100644
--- a/portal.go
+++ b/portal.go
@@ -1912,10 +1912,13 @@ func (portal *Portal) SetReply(content *event.MessageEventContent, replyTo *Repl
 		}
 		return false
 	}
+	content.RelatesTo = (&event.RelatesTo{}).SetReplyTo(message.MXID)
+	if portal.bridge.Config.Bridge.DisableReplyFallbacks {
+		return true
+	}
 	evt, err := targetPortal.MainIntent().GetEvent(targetPortal.MXID, message.MXID)
 	if err != nil {
 		portal.log.Warnln("Failed to get reply target:", err)
-		content.RelatesTo = (&event.RelatesTo{}).SetReplyTo(message.MXID)
 		return true
 	}
 	_ = evt.Content.ParseRaw(evt.Type)