startup

os.loadAPI("gui")
os.loadAPI("shop")
mon = peripheral.find("monitor")
mon.clear()

rednet.open("top")

--initialization of counting vars
amount=16
cost=0

--variables to sync with buttons
selection=nil

--runs buttons program
function getClick()
    event,side,x,y = os.pullEvent("monitor_touch")
    gui.checkxy(x,y)
end

--items in the shop
shop.newItem("Bread", 8, 93, 95, 88)
shop.newItem("F.Fries", 16, 93, 99, 88)

--------------buttons-------------------
function fillTable()
    gui.setTable("Bread",bread,7,15,3,5)
    gui.setTable("F.Fries",fries,17,25,3,5)
    gui.setTable("Checkout",checkout,31,39,10,12)
    gui.setTable("+",add,2,4,2,4)
    gui.setTable("-",subtract,2,4,8,10)
    gui.screen()
end


function bread()
    gui.flash("Bread")
    selection="Bread"
end

function fries()
    gui.flash("F.Fries")
    selection="F.Fries"
end

function checkout()
    if selection~=nil then
        gui.flash("Checkout")
        writeProcessing()
        result,stock=shop.vend(selection, amount)
        writeResult()
        sleep(1)
    end
end

function add()
    gui.flash("+")
    amount=amount+16
    if amount>64 then
        amount=64
    end
end
function subtract()
    gui.flash("-")
    amount=amount-16
    if amount<16 then
        amount=16
    end
end
----------------------------------------

function writeAmount()
    mon.setCursorPos(3,6)
    mon.write(amount)
    curX,curY=mon.getCursorPos()
    mon.setCursorPos(curX-2,6)
    mon.write("  ")
end

function writeSelection(selection)
    monW,monH=mon.getSize()
    mon.setCursorPos(9,1)
    mon.write("Current Selection: "..selection.."         ")
end

function updateCost()
    cost=shop.calcCost(selection, amount)
end

function writeCost(cost)
    monW,monH=mon.getSize()
    mon.setCursorPos(9,monH)
    mon.write("Cost: "..math.ceil(cost).." Gold Ingots")
end

function writeProcessing()
    mon.setCursorPos(9,1)
    mon.write("                                ")
    mon.setCursorPos(9,1)
    mon.write("Processing payment...")
end

function writeResult()
    if result then
        mon.setCursorPos(9,1)
        mon.write("                                ")
        mon.setCursorPos(9,1)
        mon.write("Payment received!")
    elseif not stock then
        mon.setCursorPos(9,1)
        mon.write("                                ")
        mon.setCursorPos(9,1)
        mon.write("Out of stock!")
    else
        mon.setCursorPos(9,1)
        mon.write("                                ")
        mon.setCursorPos(9,1)
        mon.write("Invalid payment!")
    end
end

fillTable()

while true do
    writeAmount()
    getClick()
    if selection~=nil then
        updateCost()
        writeCost(cost)
        writeSelection(selection)
    end
end