--[[

	Description: 
	SIP Diversion Header manipulation for Melbourne UCCX callback number handling.
	Applies to outbound calls processed by agents using callback queueing feature.
	This examines the directory number (DN) associated with the TO and DIVERSION headers
	and if they are the same it replaces the DIVERSION header DN with the FROM header DN.
	This should only ever apply for calls generated by the UCCX callback feature for the
	Melbourne call center.  

--]]


M = {}

function M.outbound_INVITE(msg)

	-- This script is applicable only for initial INVITE
		if msg:isReInviteRequest()
		then
			return
		end

	-- Get DIVERSION header - If there is no DIVERSION header then return
		local divHeader = msg:getHeader("Diversion")
		if not divHeader
		then
			return
		end
		
	-- Get URI from the DIVERSION header
		local divString = msg:getUri("Diversion")
		if divString
		then
			-- Parse URI and get DN
			local divUri = sipUtils.parseUri(divString)
			if divUri
			then
				divDN = divUri:getUser()
			end
		end
		
	-- Get URI from the TO header
		local toString = msg:getUri("To")
		if toString
		then
			-- Parse URI and get DN
			local toUri = sipUtils.parseUri(toString)
			if toUri
 			then
				toDN = toUri:getUser()
			end
		end	
		
	-- Get URI from the FROM header
		local fromString = msg:getUri("From")
		if fromString
		then
			-- Parse URI and get DN
			local fromUri = sipUtils.parseUri(fromString)
			if fromUri
			then
				fromDN = fromUri:getUser()
			end
		end	
 
	-- Compare the DNs from the DIVERSION and TO headers, if equal then this is an Invite generated
	-- by the UCCX agent callback queueing script.  This should be the only case where these DNs are
	-- the same.  In this case we want to set the DIVERSION header DN to be the same as the FROM header
	-- DN, as DIVERSION header DN must be the same as the redirecting agent phone DN.  
		if (string.match(divDN, toDN))
		then
			newHeader = string.gsub(divHeader, divDN, fromDN)
			msg:modifyHeader("Diversion", newHeader)
		end
		
end

return M