args = {...}

local PACKET_TYPE_FLOOR_LIST = "PACKET_TYPE_FLOOR_LIST"
local PACKET_TYPE_REGISTER_FLOOR = "PACKET_TYPE_REGISTER_FLOOR"
local PACKET_TYPE_GOTO_FLOOR = "PACKET_TYPE_GOTO_FLOOR"
local PACKET_TYPE_REQUEST_FLOOR_RE_REGISTER = "PACKET_TYPE_REQUEST_FLOOR_RE_REGISTER"

-- open rednet
local modem = peripheral.find("modem");

-- can change if elevator uses different configuration
local motor = peripheral.wrap("left")

local minFloorWaitTime = 2

-- check if settings have already been configured
if not fs.exists("config.settings") or args[1] == "-config" then

    -- prompt for config
    print("--- ELEVATOR CONFIG ---")
    print("these settings may be changed at any time by editing config.settings")

    print("")
    print("Enter the channel for this elevator to use:")
    settings.set("channel", tonumber(read()))

    print("")
    print("Enter the y coordinate of the floor of the elevator when the rope is fully retracted:")
    settings.set("top", tonumber(read()))

    print("")
    print("Enter the regular travel speed of the elevator:")
    settings.set("speed", tonumber(read()))

    print("")
    print("Enter the maximum speed that the elevator can reliably go:")
    settings.set("maxSpeed", tonumber(read()))

    print("")
    print("saving config...")
    settings.save("config.settings")

end

term.clear()

print("loading config...")
-- load the settings file
settings.load("config.settings")

print("")
print("reading channel: ")
local channel = settings.get("channel", 65535)
print(channel)
sleep(0.1)

print("")
print("reading top: ")
local top = settings.get("top", 310)
local currentY = 0
print(top)
sleep(0.1)

print("")
print("reading speed: ")
local speed = settings.get("speed", 32)
print(speed)
sleep(0.1)

print("")
print("reading maxSpeed: ")
local maxSpeed = settings.get("maxSpeed", 32)
print(maxSpeed)
sleep(0.1)

sleep(0.2)
term.clear()
sleep(0.1)

local numFloors = 0
local floors = {}

local moveQueue = {}

-- now the program actually STARTS...

-- go to specified y at specified speed
function goToY(newY, moveSpeed)
    if newY > top then
        deltaY = newY - currentY
        currentY = newY

        sleep(motor.translate(deltaY, moveSpeed))
    else
        print("ERROR: attempt to move to height above max height")
    end
end

-- re-center the elevator
function reCenter()
    currentY = 0
    goToY(top, maxSpeed)
end

-- go to the specified floor
function goToFloor(floorNum)
    if floorNum < numFloors then
        goToY(floors[floorNum], speed)
    else
        print("ERROR: attempt to go to invalid floor")
    end
end

function addFloorToQueue(floorNum)
    table.insert(floorQueue, floorNum)
end

-- broadcast the list of floors to all button panels
function broadcastFloorList()
    local msg = {}
    msg.type = PACKET_TYPE_FLOOR_LIST
    msg.floors = floors
    modem.transmit(channel, channel, msg)
end

function reRegisterFloors()
    local msg = {}
    msg.type = PACKET_TYPE_REQUEST_FLOOR_RE_REGISTER
    modem.transmit(channel, channel, msg)

    floors = {}
end

-- add a floor given a messageData from a PACKET_TYPE_REGISTER_FLOOR packet
function registerFloor(dat)

    if dat.y == nil then
        print("ERROR: bad packet")
        return
    end

    -- check if the floor already exists
    for i = 0, numFloors then
        if floors[i].y == dat.y then
            return
        end
    end

    floors[numFloors] = dat
    numFloors = numFloors + 1

    -- sort the floors by y axis
    table.sort(floors, function(lhs, rhs)
        return lhs.y < rhs.y
    end)

    broadcastFloorList()
end

-- open the modem for channel
modem.closeAll()
modem.open(channel)

-- program loops

-- messages:
--  type(string) type of message
--  data(any) date that the message contains

-- wait for and process packets from button panels
function networkPacketManager()

    while true do

        --pull modem_message event
        local event, modemSide, senderChannel, replyChannel, message, senderDistance = os.pullEvent("modem_message")

        if message.type ~= nil then
            local msgType = message.type
            local msgData = message.data

            if msgType == PACKET_TYPE_REGISTER_FLOOR then
                registerFloor(msgData)
            else if msgType == PACKET_TYPE_GOTO_FLOOR then
                if msgData.floorNum ~= nil then
                    addFloorToQueue(msgData.floorNum)
                else
                    print("ERROR: bad packet")
                end
            end

        else
            print("ERROR: bad packet")
        end
    end while

end

-- move the elevator and sutch (must by async ass it will sleep when moving)
function main()

    while true do

        -- check if there is a floor in the queue
        local numFloorsInQueue = table.getn(floorQueue)
        if numFloorsInQueue ~= 0 then
            local floorNum = floorQueue[0]
            table.remove(floorQueue, 1)

            goToFloor(floorNum)

            -- wait so the player can get on/off the elevator
            sleep(minFloorWaitTime)
        end

        sleep(0)
    end while

end

-- requrest all floors be re-registered
reRegisterFloors()
parallel.waitForAny(networkPacketManager, main)
modem.closeAll()