MM-19508 Extend ShouldProcessMessage to filter out from_webhoo… (#13270)

Extend ShouldProcessMessage to filter out from_webhook posts

plugin/helpers_bots.go

@@ -66,6 +66,7 @@ type ShouldProcessMessageOption func(*shouldProcessMessageOptions)
 type shouldProcessMessageOptions struct {
 	AllowSystemMessages bool
 	AllowBots           bool
+	AllowWebhook        bool
 	FilterChannelIDs    []string
 	FilterUserIDs       []string
 	OnlyBotDMs          bool
@@ -89,6 +90,15 @@ func AllowBots() ShouldProcessMessageOption {
 	}
 }
 
+// AllowWebhook configures a call to ShouldProcessMessage to return true for posts from webhook.
+//
+// As it is typically desirable only to consume messages from human users of the system, ShouldProcessMessage ignores webhook messages by default.
+func AllowWebhook() ShouldProcessMessageOption {
+	return func(options *shouldProcessMessageOptions) {
+		options.AllowWebhook = true
+	}
+}
+
 // FilterChannelIDs configures a call to ShouldProcessMessage to return true only for the given channels.
 //
 // By default, posts from all channels are allowed to be processed.
@@ -138,6 +148,10 @@ func (p *HelpersImpl) ShouldProcessMessage(post *model.Post, options ...ShouldPr
 		return false, nil
 	}
 
+	if !messageProcessOptions.AllowWebhook && post.Props["from_webhook"] == "true" {
+		return false, nil
+	}
+
 	if !messageProcessOptions.AllowBots {
 		user, appErr := p.API.GetUser(post.UserId)
 		if appErr != nil {