--------------------------------------------------------------------------------------
-- PZB Kombi (1000/2000Hz) Inductor
-- (goes next to Hp or VR or Kombi signal)
-- KUJU / Rail Simulator
-- StS 03.04.2011
-- Slightly modified by Prellbock with the kind help of schuster 24-Okt-2012 (rail-sim.de)
	-- Changes: Added a request for distant signals
--------------------------------------------------------------------------------------

-- debugging stuff
DEBUG = true 					-- set to true to turn debugging on

function DebugPrint( message )
	if (DEBUG) then
		Print( message )
	end
end


-- global constants
CLEAR 			= 0
WARNING 			= 1
BLOCKED 			= 2

-- message ids
CUSTOM_MSG			= 15

-- args
PZB_1000_ARG		= "1000"
PZB_2000_ARG		= "2000"

--------------------------------------------------------------------------------------
-- INITIALISE
--
function Initialise ()
	mDone = 0
end

--------------------------------------------------------------------------------------
-- ON CONSIST PASS
--
function OnConsistPass ( prevFrontDist, prevBackDist, frontDist, backDist, linkIndex )

	-- if the consist is crossing the inductor now
	if ( frontDist > 0 and backDist < 0 ) or ( frontDist < 0 and backDist > 0 ) then
	
		-- if the consist was previously before signal then the crossing has just started
		if (prevFrontDist > 0 and prevBackDist > 0) then
			
			if (mDone ~= 1) then
			
				mDone = 1
				
				-- Request state of next main signal (german: Hauptsignal)
				local nextSignalState = Call( "GetNextSignalState", "", 1, 1, 0 )
				-- Request state of next distant signal (german: Vorsignal)
				local nextDistantState = Call( "GetNextDistantState", "", 1, 1, 0 )

				DebugPrint( ("DEBUG: PZB Kombi OnConsistPass: Crossing started, next main signal state is " .. nextSignalState) )
				DebugPrint( ("DEBUG: PZB Kombi OnConsistPass: Crossing started, next distant signal state is " .. nextDistantState) )

				-- If the distant signal ahead is on warning
				if (nextDistantState == WARNING) then
					Call( "SendConsistMessage", CUSTOM_MSG, PZB_1000_ARG )
				end

				-- If the main signal ahead is blocked
				if (nextSignalState == BLOCKED) then
					Call( "SendConsistMessage", CUSTOM_MSG, PZB_2000_ARG )
					Call( "SendConsistMessage", CUSTOM_MSG, PZB_1000_ARG )
				end
			end
		end
	else
		-- Reset once train has passed
		if (mDone ~= 0) then
			DebugPrint( ("DEBUG: PZB Kombi OnConsistPass: Crossing finished") )
			mDone = 0
		end
	end
end

--------------------------------------------------------------------------------------
-- ON SIGNAL MESSAGE
--
function OnSignalMessage( message, parameter, direction, linkIndex )

	-- Forward every message unchanged, unless it's from a train straddling our link
	if parameter ~= "DoNotForward" then
		Call( "SendSignalMessage", message, parameter, -direction, 1, linkIndex )
	end
end

--------------------------------------------------------------------------------------
-- JUNCTION STATE CHANGE
-- Left blank - PZB inductors always only have one link
--
function OnJunctionStateChange( junction_state, parameter, direction, linkIndex )
	
end