--[[
    Cross 3	Standard Schedule Program
]]
require("libevent")
require("util")
require("checkarg")
require("queue")
local sides = require("sides")

-- Config your update functions here (Do not change variable name)
local redin1 = proxy("redstone", "")
local redin2 = proxy("redstone", "")
local redin3 = proxy("redstone", "")
local redout1 = proxy("redstone", "")

-- Redirect Table
local redirect_tb = {
    ["ab_st"]={redin1,sides.north},
	["ab_sr"]={redin1,sides.east},
	["ab_lout"]={redin1,sides.south},
	["ab_left"]={redin1,sides.west},
	
	["ba_st"]={redin2,sides.north},
	["ba_sr"]={redin2,sides.east},
	["ba_lout"]={redin2,sides.south},
	["ba_left"]={redin2,sides.west},

	["c_st"]={redin3,sides.north},
	["c_sr"]={redin3,sides.east},
	["c_lout"]={redin3,sides.south},
	["c_left"]={redin3,sides.west},
	
	["ab_ks"]={redout1,sides.north},
	["ab_m"]={redout1,sides.east},
	["ba_ks"]={redout1,sides.south},
	["ba_m"]={redout1,sides.west},
	
	["c_ks"]={redout2,sides.north},
	["c_m"]={redout2,sides.east},
	
	["last_unused"]={redin1,sides.north}
}

local function getNameFromRaw(Device, Side)
    for k, t in pairs(redirect_tb) do
        if (t[1].address == Device and t[2] == Side) then
            return k
        end
    end

    return nil
end

local function getRawFromName(Name)
    return redirect_tb[Name][1], redirect_tb[Name][2]
end

local function enabledevice(Name)
    local d, s = getRawFromName(Name)
    if (d ~= nil and s ~= nil) then
        d.setOutput(s, 15)
    end
end

local function disabledevice(Name)
    local d, s = getRawFromName(Name)
    if (d ~= nil and s ~= nil) then
        d.setOutput(s, 0)
    end
end

local function readdevice(Name)
    local d, s = getRawFromName(Name)
    if (d ~= nil and s ~= nil) then
        return d.getInput(s)
    else
        -- Critical error
        error("failed to read device input")
    end
end

local function trigger(Name)
    enabledevice(Name)
    os.sleep(0.25)
    disabledevice(Name)
end

local evl = Queue.new()

local function restone_delegator(Name, callback_func)
    evl:push(
        AddEventListener(
            "redstone_changed",
            function(ev, dev, sd, from, to)
                if (getNameFromRaw(dev, sd) == Name) then
                    callback_func(from, to)
                end
            end
        )
    )
end

local bus=Queue.new();

local function redstone_event(DeviceName,OnEvent,OffEvent)
	if(OnEvent~=nil and OffEvent~=nil) then 
		redstone_delegator(DeviceName,
			function(from,to)
				if(from<to) then 
					bus:push(OnEvent)
				else
					bus:push(OffEvent)
				end
			end)
	elseif(OnEvent~=nil) then 
		redstone_delegator(DeviceName,
			function(from,to)
				if(from<to) then 
					bus:push(OnEvent)
				end
			end)
	elseif(OffEvent~=nil) then
		redstone_delegator(DeviceName,
			function(from,to)
				if(from>to) then
					bus:push(OffEvent)
				end
			end)
	end
end

local function doInit()
	evl:push(
        AddEventListener(
            "interrupted",
            function()
                bus:push("stop")
            end
        )
    )

	redstone_event("ab_st","a_new_train","a_train_left")
	redstone_event("ba_st","b_new_train","b_train_left")
	redstone_event("c_st","c_new_train","c_train_left")
	redstone_event("ab_left","b_detect_start","b_detect_end")
	redstone_event("ba_left","a_detect_start","a_detect_end")
	redstone_event("c_left","c_detect_start","c_detect_end")
end

-- Status
-- Out busy flag
local a_busy,b_busy,c_busy=false,false,false
local crosslocked=false

local function doCheck()
	for k, vt in pairs(redirect_tb) do
        if (vt[1] == nil) then
            error("Check Failed. Please review your redstone configure")
        end
    end

    print("Check Pass.")
end

local function doClearOutput()
	local smt={"ab_ks","ab_m","ba_ks","ba_m","c_ks","c_m"}
	
	for k, v in pairs(smt) do
		disabledevice(v)
	end
end

local function CCSMain()
	doCheck()
	doClearOutput()
	doInit()
	
	print("CCS Started. Press Ctrl+C to stop.")
	local running=true
	while(running) do
		os.sleep(0.25)
		local ev="no_evnet"
		if(bus:top()~=nil) then
			ev=bus:pop();
		end
		
		if (ev ~= "no_event") then
            print(ev)
        end
		
		if (ev == "no_event") then
            -- No event, no action.
        elseif (ev == "stop") then
            running = false
		elseif (ev=="delay") then
			os.sleep(0.25)
		elseif (ev=="a_new_train") then -- New Train From A
			local done=false
			if(readdevice("ab_sr")>0) then -- Turn to C
				if( (not c_busy) and (not crosslocked) and readdevice("c_lout")>0) then
					c_busy=true
					crosslocked=true
					enabledevice("ab_m")
					trigger("ab_ks")
					done=true
				end
			else -- Go directly to B
				if( (not b_busy) and (not crosslocked) and readdevice("ab_lout")>0) then 
					b_busy=true
					crosslocked=true
					disabledevice("ab_m")
					trigger("ab_ks")
					done=true
				end
			end
			
			if(not done) then 
				bus:push(ev)
			end
		
		elseif (ev=="b_new_train") then -- New Train From B
			local done=false
			if(readdevice("ba_sr")>0) then -- Turn to C
				if( (not c_busy) and readdevice("c_lout")>0) then
					c_busy=true
					enabledevice("ba_m")
					trigger("ba_ks")
					done=true
				end
			else -- Go directly to A
				if( (not a_busy) and (not crosslocked) and readdevice("ba_lout")>0) then 
					a_busy=true
					crosslocked=true
					disabledevice("ba_m")
					trigger("ba_ks")
					done=true
				end
			end
			
			if(not done) then 
				bus:push(ev)
			end
		elseif (ev=="c_new_train") then -- New Train From C
			local done=false
			if(readdevice("ba_sr")>0) then -- Turn to A
				if( (not a_busy) and readdevice("ba_lout")>0) then
					a_busy=true
					enabledevice("c_m")
					trigger("c_ks")
					done=true
				end
			else -- Go directly to B
				if( (not b_busy) and (not crosslocked) and readdevice("ab_lout")>0) then 
					b_busy=true
					crosslocked=true
					disabledevice("c_m")
					trigger("c_ks")
					done=true
				end
			end
			
			if(not done) then 
				bus:push(ev)
			end
		elseif(ev=="a_detect_end") then
			a_busy=false
			crosslocked=true
		elseif(ev=="b_detect_end") then
			b_busy=false
			crosslocked=true
		elseif(ev=="c_detect_end") then
			c_busy=false
			crosslocked=true
		end
	end
end