--[[
Station 2/3 Schedule Program
]]
require("util")
local sides = require("sides")
local event = require("event")
--[[
Redstone Signals
Direction_[Type][Info]: number
]]
local ab_st, ab_sr, ab_lin, ab_lout
local ba_st, ba_sr, ba_lin, ba_lout

local ab_ko, ab_m, ab_ks = 0, 0, 0
local ba_ko, ba_m, ba_ks = 0, 0, 0
local mid_ka, mid_kb = 0, 0

-- Config your update functions here (Do not change function name)
local redin1 = proxy("redstone", "")
local redin2 = proxy("redstone", "")
local redout1 = proxy("redstone", "")
local redout2 = proxy("redstone", "")

local function updateRedstoneInput()
    ab_st = redin1.getInput(sides.north)
    ab_sr = redin1.getInput(sides.east)
    ba_st = redin1.getInput(sides.south)
    ba_sr = redin1.getInput(sides.west)
    ab_lin = redin2.getInput(sides.north)
    ab_lout = redin2.getInput(sides.east)
    ba_lin = redin2.getInput(sides.south)
    ba_lout = redin2.getInput(sides.west)
end

local function updateRedstoneOutput()
    redout1.setOutput(sides.north, ab_ko)
    redout1.setOutput(sides.east, ab_m)
    redout1.setOutput(sides.south, ab_ks)
    redout1.setOutput(sides.west, mid_ka)
    redout2.setOutput(sides.north, ba_ko)
    redout2.setOutput(sides.east, ba_m)
    redout2.setOutput(sides.south, ba_ks)
    redout2.setOutput(sides.west, mid_kb)
end

-- Internal Schedule Status (Notice: Program must start without any trains in station)
local mid_direction
local ab_station_time = 0
local ba_station_time = 0
local mid_time = 0
local ab_exit_time = 0
local ba_exit_time = 0

-- Debug Output
local dprint = print

local function debugClearOutput()
    if(dprint ~= nil) then
        os.execute("clear")
    end
end

local function debugOutputInfo()
    dprint("ab_st",ab_st,"ab_sr",ab_sr,"ba_st",ba_st,"ba_sr",ba_sr,"ab_lin",ab_lin,"ab_lout",ab_lout,"ba_lin",ba_lin,"ba_lout",ba_lout)
    dprint("mid_direction",mid_direction,"ab_station_time",ab_station_time,"ba_station_time",ba_station_time,"mid_time",mid_time,"ab_exit_time",ab_exit_time,"ba_exit_time",ba_exit_time)
end

local function debugValueInfo()
    dprint("ab_ko",ab_ko,"ab_m",ab_m,"ab_ks",ab_ks,"mid_ka",mid_ka,"ba_ko",ba_ko,"ba_m",ba_m,"ba_ks",ba_ks,"mid_kb",mid_kb)
end

--[[
    Internal Functions
]]
local function doInit()
    -- Flash output to zero.
    updateRedstoneOutput()
end

local function doCheck()
    if(redin1==nil or redin2==nil or redout1==nil or redout2==nil) then 
        print("Redstone Configure")
    end
end

-- Main Program
local function main()
    doCheck()
    doInit()
    while true do
        debugClearOutput()
        -- Flush input
        updateRedstoneInput()
        debugOutputInfo()
        -- Update status
        if (ab_station_time > 0) then
            ab_station_time = ab_station_time + 1
        end
        if (ba_station_time > 0) then
            ba_station_time = ba_station_time + 1
        end
        if (mid_time > 0) then
            mid_time = mid_time + 1
        end
        if (ab_exit_time > 0) then
            ab_exit_time = ab_exit_time + 1
            if (ab_exit_time > 10) then -- Exit will reset in 10 loops (5seconds)
                ab_exit_time = 0
            end
        end
        if (ba_exit_time > 0) then
            ba_exit_time = ba_exit_time + 1
            if (ba_exit_time > 10) then -- Exit will reset in 10 loops (5seconds)
                ba_exit_time = 0
            end
        end

        -- Judge Incoming bus.
        if (ab_st > 0) then -- New incoming bus from A to B
            if (ab_sr > 0) then -- This bus want to stop
                if (ab_station_time == 0) then -- If AB Station is free
                    dprint("A-->B Train In")
                    ab_ko = 15 -- enable to allow incoming
                    ab_ks = 0 -- disable to let it stop
                    ab_m = 0 -- disable to allow incoming to station
                    ab_station_time = 1 -- Start Time Counter
                else -- AB Station is not free
                    -- This train should wait outside the station
                    dprint("A-->B Train Pending")
                end
            else -- This bus want to pass by
                if (mid_time == 0) then -- Mid is free
                    dprint("A-->Mid Train In")
                    ab_ko = 15 -- enable to allow incoming
                    ab_m = 15 -- enable motor to let it pass.
                    mid_ka = 15 -- enable switch from A
                    mid_kb = 0 -- disable switch to B
                    mid_direction = "ab"
                    mid_time = 1 -- Start time counter
                else -- Mid is busy
                    dprint("A-->Mid Train Pending")
                    -- This train should wait outside the station
                end
            end
        end

        if (ba_st > 0) then -- New incoming bus from B to A
            if (ba_sr > 0) then -- This bus want to stop
                if (ba_station_time == 0) then -- If BA Station is free
                    dprint("B-->A Train In")
                    ba_ko = 15 -- enable to allow incoming
                    ba_ks = 0 -- disable to let it stop
                    ba_m = 0 -- disable to allow incoming to station
                    ba_station_time = 1 -- Start Time Counter
                else -- BA Station is not free
                    -- This train should wait outside the station
                    dprint("B-->A Train Pending")
                end
            else -- This bus want to pass by
                if (mid_time == 0) then -- Mid is free
                    dprint("B-->Mid Train In")
                    ba_ko = 15 -- enable to allow incoming
                    ba_m = 15 -- enable motor to let it pass.
                    mid_ka = 0
                    mid_kb = 15
                    mid_direction = "ba"
                    mid_time = 1
                else -- Mid is busy
                    dprint("B-->Mid Train Pending")
                    -- This train should wait outside the station
                end
            end
        end

        if (ab_lout > 0 and ab_exit_time == 0) then -- AB next free
            -- Judge which train should pass.
            if (ab_station_time > 16 and (mid_time > 0 and mid_direction == "ab")) then -- Two Trains
                if (ab_station_time > mid_time) then -- StationTrain wait longer.
                    dprint("A-->B Train Out")
                    ab_station_time = 0 -- Stop counter
                    ab_ks = 15 -- enable swith to let it go
                    ab_exit_time = 1
                else -- MidTrain wait longer
                    dprint("Mid-->B Train out")
                    mid_time = 0 -- Stop Counter
                    mid_kb = 15
                    ab_exit_time = 1
                end
            elseif (ab_station_time > 16) then --Only Station Train
                dprint("A-->B Train Out")
                ab_station_time = 0
                ab_ks = 15
                ab_exit_time = 1
            elseif (mid_time > 0 and mid_direction == "ab") then -- Only Mid Train
                dprint("Mid-->B Train Out")
                mid_time = 0
                mid_kb = 15
                ab_exit_time = 1
            end -- No train
        end -- End of AB judge

        if (ba_lout > 0 and ba_exit_time == 0) then -- BA next free
            -- Judge which train should pass.
            if (ba_station_time > 16 and (mid_time > 0 and mid_direction == "ba")) then -- Two Trains
                if (ba_station_time > mid_time) then -- StationTrain wait longer.
                    dprint("B-->A Train Out")
                    ba_station_time = 0 -- Stop counter
                    ba_ks = 15 -- enable swith to let it go
                    ba_exit_time = 1
                else -- MidTrain wait longer
                    dprint("Mid-->A Train Out")
                    mid_time = 0 -- Stop Counter
                    mid_ka = 15
                    ba_exit_time = 1
                end
            elseif (ba_station_time > 16) then --Only Station Train
                dprint("B-->A Train Out")
                ba_station_time = 0
                ba_ks = 15
                ba_exit_time = 1
            elseif (mid_time > 0 and mid_direction == "ba") then -- Only Mid Train
                dprint("Mid-->A Train Out")
                mid_time = 0
                mid_ka = 15
                ba_exit_time = 1
            end -- No train
        end

        debugValueInfo()

        -- Set output
        updateRedstoneOutput()

        -- Sleep for next loop
        dprint("==========")
        os.sleep(0.5)
    end
end

print("Start!")
main()
print("Stop!")