SkyScraper

function centerPrint(sText)
    local w, h = term.getSize()
    local x, y = term.getCursorPos()
    x = math.max(math.floor((w / 2) - (#sText / 2)), 0)
    term.setCursorPos(x, y)
    term.write(sText)
end

function clear()
    term.clear()
    term.setCursorPos(1, 1)
end

function nextLine(n)
    n = n or 1
    local x, y = term.getCursorPos()
    term.setCursorPos(x, y + n)
end

-- Update
    local url = "https://raw.github.com/Sxw1212/SkyScraper/master/"
    local res = http.get(url .. "elev.lua")
    if res then
        local fh = fs.open("/startup", "w")
        fh.write(res.readAll())
        fh.close()
    else
        clear()
        centerPrint("SkyScraper by Sxw1212")
        nextLine()
        centerPrint("Warning: Updater failed")
        sleep(1)
    end
    local res = http.get(url .. "goroutine.lua")
    if res then
        local fh = fs.open("/goroutine", "w")
        fh.write(res.readAll())
        fh.close()
    else
        clear()
        centerPrint("SkyScraper by Sxw1212")
        nextLine()
        centerPrint("Warning: Updater failed")
        sleep(1)
    end

-- System test
    os.loadAPI("goroutine")

    clear()
    centerPrint("SkyScraper by Sxw1212")
    nextLine()
    centerPrint("Elevator starting. Please wait")
    nextLine()
    centerPrint("Running System Test...")

    if peripheral.getType("bottom") ~= "rednet_cable" then
        nextLine()
        centerPrint("Error: No cable on bottom")
        error()
    end
    if peripheral.getType("back") ~= "modem" then
        nextLine()
        centerPrint("Error: No modem on back")
        error()
    end

    sleep(0.25)

    nextLine()
    centerPrint("System test completed, starting...")

    sleep(0.25)
    clear()

-- Vars
    cfg = {}
    PORT = 50101
    PREFIX = "SKYSCRAPER:"
    COLORS = {
        ["detector"] = colors.white,
        ["boarding"] = colors.orange,
        ["elevator"] = colors.magenta
    }
    MODEM = peripheral.wrap("back")
    ELEVATORS = {}
    FLOORS = {"Call Elevator"}
    STAT = "CLEAR"
    SELECTED = 1
    REFRESHQUEUE = true
    MODEM.open(PORT)

-- Helper functions

    function refresh()
        if REFRESHQUEUE then
            REFRESHQUEUE = false
            os.queueEvent("refresh")
        end
    end

    function table.copy(t)
        local t2 = {}
        for k,v in pairs(t) do
            t2[k] = v
        end
        return t2
    end
    function send(msg)
        MODEM.transmit(PORT, PORT, PREFIX .. textutils.serialize(msg))
    end

    function recv()
        while true do
            local _, _, _, _, msg = os.pullEvent("modem_message")
            if msg:sub(1, #PREFIX) == PREFIX then
                local trans = msg:sub((#PREFIX)+1)
                return textutils.unserialize(trans)
            end
        end
    end

    function menuCompat()
        -- Somebody help me, I have no idea how else to do this
        local smenu = table.copy(ELEVATORS)
        smenu[#smenu+1] = cfg
        table.sort(smenu, function (a,b) return (a.y > b.y) end)

        local sorted = {}
        local len = #smenu
        for i = 1, len do
            sorted[i] = smenu[i].name
        end
        table.insert(sorted, 1, "Call Elevator")
        FLOORS = sorted
    end

    function addFloor(data)
        local contains = false
        for k, v in pairs(ELEVATORS) do
            if v.y == data.y then
                contains = true
                ELEVATORS[k].name = data.name
            end
        end
        if not contains then
            table.insert(ELEVATORS, data)
        end
        menuCompat()
    end

    function runmenu()
        local function render()
            clear()
            term.setCursorPos(1, 1)
            centerPrint("SkyScraper by Sxw1212")
            nextLine(2)
            for k, v in pairs(FLOORS) do
                local val = v
                if cfg.name == v then
                    val = "-" .. val .. "-"
                elseif SELECTED == k then
                    val = "[" .. val .. "]"
                end
                centerPrint(val)
                nextLine()
            end
        end
        render()
        while true do
            local e, k = os.pullEvent("key")
            if k == keys.up then
                if SELECTED ~= 1 then
                    if FLOORS[SELECTED - 1] ~= cfg.name then
                        SELECTED = SELECTED - 1
                    elseif SELECTED > 2 then
                        SELECTED = SELECTED - 2
                    end
                end
            elseif k == keys.down then
                if FLOORS[SELECTED + 1] then
                    if FLOORS[SELECTED + 1] ~= cfg.name then
                        SELECTED = SELECTED + 1
                    elseif FLOORS[SELECTED + 2] then
                        SELECTED = SELECTED + 2
                    end
                end
            elseif k == keys.enter then
                local sel = FLOORS[SELECTED]
                SELECTED = 1
                return sel
            end
            render()
        end
    end

-- Config
    if not fs.exists("/sky.cfg") then
        centerPrint("SkyScraper configuration")
        term.setCursorPos(1, 2)
        write("Y-Level: ")
        cfg.y = tonumber(read())
        write("Floor name: ")
        cfg.name = read()

        local fh = fs.open("/sky.cfg", "w")
        fh.write(textutils.serialize(cfg))
        fh.close()

        centerPrint("Done!")
        sleep(0.25)
        clear()
    end
    local fh = fs.open("/sky.cfg", "r")
    cfg = textutils.unserialize(fh.readAll())
    fh.close()
    if cfg.y and cfg.name then
        centerPrint("SkyScraper configuration")
        nextLine()
        centerPrint("Loaded from file!")
        clear()
        cfg.y = tonumber(cfg.y)
    else
        fs.delete("/sky.cfg")
        os.reboot()
    end

-- Announce
    send({ "DISCOVER", cfg })

-- Handlers

    function msgHandler()
        while true do
            local msg = recv()
            if msg[1] == "CALL" then
                if STAT == "COMING" then
                else
                    STAT = "BUSY"
                    rs.setBundledOutput("bottom", COLORS.boarding)
                    sleep(1)
                    rs.setBundledOutput("bottom", 0)
                    refresh()
                end
            elseif msg[1] == "SENDING" then
                STAT = "BUSY"

                if tostring(msg[2]) == tostring(cfg.y) then
                    STAT = "COMING"
                    rs.setBundledOutput("bottom", COLORS.elevator)
                end
                refresh()
            elseif msg[1] == "DISCOVER" then
                addFloor(msg[2])
                send({ "HELLO", cfg })
                refresh()
            elseif msg[1] == "HELLO" then
                addFloor(msg[2])
                refresh()
            elseif msg[1] == "CLEAR" then
                STAT = "CLEAR"
                refresh()
                rs.setBundledOutput("bottom", 0)
            elseif msg[1] == "RESET" then
                os.reboot()
            end
        end
    end

    function menu()
        if STAT == "CLEAR" then
            local x, y = term.getSize()
            local floor = runmenu()
            if floor == "Call Elevator" then
                send({ "CALL", cfg })
                STAT = "COMING"
                rs.setBundledOutput("bottom", COLORS.elevator)
            elseif floor ~= cfg.name then
                for k, v in pairs(ELEVATORS) do
                    if v.name == floor then
                        send({ "SENDING", v.y, cfg})
                    end
                end
                STAT = "BUSY"
                rs.setBundledOutput("bottom", COLORS.boarding)
            end
            refresh()
        elseif STAT == "BUSY" then
            clear()
            centerPrint("SkyScraper by Sxw1212")
            nextLine(7)
            centerPrint("Elevator busy, please wait")
            os.pullEvent("AReallyLongEventThatYou'dBetterNotCallOrElse...")
        elseif STAT == "COMING" then
            clear()
            centerPrint("SkyScraper by Sxw1212")
            nextLine(7)
            centerPrint("Elevator coming, please wait")
            while true do
                os.pullEvent("redstone")
                if colors.test(rs.getBundledInput("bottom"), COLORS.detector) then
                    STAT = "CLEAR"
                    send({ "CLEAR", cfg })
                    rs.setBundledOutput("bottom", 0)
                    refresh()
                end
            end
        end
    end

    function main()
        goroutine.spawn("msgHandler", msgHandler)
        goroutine.assignEvent("msgHandler", "modem_message")
        while true do
            REFRESHQUEUE = true
            goroutine.spawn("menu", menu)

            goroutine.assignEvent("menu", "key")
            goroutine.assignEvent("menu", "redstone")

            os.pullEvent("refresh")

            sleep(0.1)
            goroutine.kill("menu")
            sleep(0.1)
        end
    end

    goroutine.run(main)