From 0702410a9a946687f895f68a9a34d6eacf8aad67 Mon Sep 17 00:00:00 2001
From: Stephen Paul Weber <singpolyma@singpolyma.net>
Date: Sat, 27 May 2017 14:00:06 -0500
Subject: [PATCH] Allow inserting Blather handler before others

Mostly useful for extending the existing SGXcatapult application from
elsewhere.
---
 sgx-catapult.rb | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/sgx-catapult.rb b/sgx-catapult.rb
index 57319d08f3adc2a053da73a85105527c4bcb848d..410afc1352ebcf19560277ddd020bcad520cd322 100755
--- a/sgx-catapult.rb
+++ b/sgx-catapult.rb
@@ -48,15 +48,25 @@ end
 
 class SGXClient < Blather::Client
 	def register_handler(type, *guards, &block)
-		super(type, *guards) do |stanza|
-			begin
-				v = block.call(stanza)
-				v.catch(&method(:panic)) if v.is_a?(Promise)
-				true # Do not run other handlers unless throw :pass
-			rescue Exception => e
-				panic(e)
-			end
-		end
+		super(type, *guards) { |stanza| wrap_handler(stanza, &block) }
+	end
+
+	def register_handler_before(type, *guards, &block)
+		check_handler(type, guards)
+		handler = lambda { |stanza| wrap_handler(stanza, &block) }
+
+		@handlers[type] ||= []
+		@handlers[type].unshift([guards, handler])
+	end
+
+protected
+
+	def wrap_handler(stanza, &block)
+		v = block.call(stanza)
+		v.catch(&method(:panic)) if v.is_a?(Promise)
+		true # Do not run other handlers unless throw :pass
+	rescue Exception => e
+		panic(e)
 	end
 end
 
@@ -81,6 +91,10 @@ module SGXcatapult
 		client.write(stanza)
 	end
 
+	def self.before_handler(type, *guards, &block)
+		client.register_handler_before(type, *guards, &block)
+	end
+
 	def self.send_media(from, to, media_url, desc=nil, subject=nil)
 		# we assume media_url is of the form (always the case so far):
 		#  https://api.catapult.inetwork.com/v1/users/[uid]/media/[file]