[Lua] Help with buttons

button = {}
input = {}
calc = ""

term.setBackgroundColor(colors.black)
term.setTextColor(colors.white)
term.clear()

function printVerticalLine(lineX, startingY, endingY)
local curX, curY = term.getCursorPos()
term.setBackgroundColor(colors.white)
for lineY = startingY, endingY do
term.setCursorPos(lineX, lineY)
term.write(" ")
end
term.setCursorPos(curX, curY)
end

function printHorizontalLine(yLine, startingX, endingX)
local curX, curY = term.getCursorPos()
term.setBackgroundColor(colors.white)
for xLine = startingX, endingX do
term.setCursorPos(xLine, yLine)
term.write(" ")
end
term.setCursorPos(curX, curY)
end

function drawTable()
 printVerticalLine(2,2,18)
 --Left Border
 printVerticalLine(20,2,18)
 --Right Border
 printVerticalLine(8,6,18)
 --Left Seperator
 printVerticalLine(14,6,18)
 --Right Seperator
 printHorizontalLine(2,2,20)
 --Top
 printHorizontalLine(6,2, 20)
 --Upper Before Keys
 printHorizontalLine(18,2,20)
 --Bottom
 printHorizontalLine(10,2,20)
 --Upper Seperator
 printHorizontalLine(14,2,20)
 --Lower Seperator
 term.setBackgroundColor(colors.black)
end

function drawFunctionsTable()
 printHorizontalLine(6,32,50)
 --Top
 printHorizontalLine(10,32,50)
 printHorizontalLine(14,32,50)
 printHorizontalLine(18,32,50)
 --Bottom
 printVerticalLine(32,6,18)
 --Left Border
 printVerticalLine(38,6,14)
 printVerticalLine(44,6,18)
 printVerticalLine(50,6,18)
 --Right Border

 term.setBackgroundColor(colors.black)
end

function drawExtraButtonsTable()
 --Help, Color settings, 2nd button for filling table with ExtraFunctions
 printVerticalLine(23,6,18)
 --Left Border
 printVerticalLine(29,6,18) 
 --Right Border
 printHorizontalLine(6,23,29)
 --Top
 printHorizontalLine(10,23,29)
 printHorizontalLine(14,23,29)
 printHorizontalLine(18,23,29)
 --Bottom
end

function setTable(name, xmin, xmax, ymin, ymax)
 button[name] = {}
 button[name]["numb"] = name
 button[name]["xmin"] = xmin
 button[name]["xmax"] = xmax
 button[name]["ymin"] = ymin
 button[name]["ymax"] = ymax
end

function fillTable()
 setTable("1", 3, 7, 15, 17)
 setTable("2", 9, 13, 15, 17)
 setTable("3", 15, 19, 15, 17)
 setTable("4", 3, 7, 11, 13)
 setTable("5", 9, 13, 11, 13)
 setTable("6", 15, 19, 11, 13)
 setTable("7", 3, 7, 7, 9)
 setTable("8", 9, 13, 7, 9)
 setTable("9", 15, 19, 7, 9)
end

function fillFunctionsTable()
 setTable("C", 33,37,7,9)
 setTable(".", 39,43,7,9)
 setTable("/", 45,49,7,9)
 setTable("+", 33,37,11,13)
 setTable("-", 39,43,11,13)
 setTable("*", 45,49,11,13)
 setTable("0", 33,43,15,17)
 setTable("=", 45,49,15,17)
end

function fillExtraFunctions()
 setTable("^", 33,37,7,9)
 setTable("rt", 39,43,7,9)
 --setTable("", 45,49,7,9)
 --setTable("", 33,37,11,13)
 --setTable("", 39,43,11,13)
 --setTable("", 45,49,11,13)
 --setTable("", 33,43,15,17)
 --setTable("", 45,49,15,17)
end

function fillExtraButtonsTable()
 setTable("F",24,28,7,9)
 setTable("H",24,28,11,13)
 setTable("c",24,28,15,17)
end

function checkClick(tab, mx, my)
for i, v in pairs(tab) do
if mx >= v.xmin and mx <= v.xmax and my >= v.ymin and my <= v.ymax then
return true, v.numb
end
end
return false, nil
end

function screen()
term.setBackgroundColour(colours.black)
term.setTextColour(colours.white)
for name,data in pairs(button) do
local yspot = (data["ymin"] + data["ymax"]) / 2
local xspot = (data["xmin"] + data["xmax"]) / 2
term.setCursorPos(xspot, yspot)
write(name)
end
end

function redraw()
 term.setCursorPos(4,4)
 term.clearLine()
 drawTable()
end

function displayHelp()
 term.clear()
 Help()
end

function setInput1()
 input[1] = tonumber(calc)
 input[2] = numb
 redraw()
 calc = ""
 numb = ""
end

function enterPress()
 input[3] = tonumber(calc)
 redraw()
 calc = ""
 numb = ""
 if input[2] == "+" then
  Output = input[1] + input[3]
 elseif input[2] == "-" then
  Output = input1 - input[3]
 elseif input[2] == "*" then
  Output = input[1] * input[3]
 elseif input[2] == "/" then
  Output = input[1] / input[3]
 elseif input[2] == "^" then
  Output = input[1] ^ input[3]
 elseif input[2] == "rt" then
  Output = math.sqrt(input[1]) 
 end 
 write(Output)
 input[1] = Output  
end
--[[ Running Code ]]-- 

drawTable()
drawFunctionsTable()
drawExtraButtonsTable()
fillTable()
fillFunctionsTable()
fillExtraButtonsTable()
screen()

while true do
 local e, but, x, y = os.pullEvent("mouse_click")
 if but == 1 then
  bValid, numb = checkClick(button, x, y)
  if bValid then
   if numb == "C" then 
    redraw()
    for i = 1,3 do
     input[i] = nil
    end
    calc = ""
   else
    if numb == "+" then
     setInput1()
    elseif numb == "-" then
     setInput1()
    elseif numb == "*" then
     setInput1()
    elseif numb == "/" then
     setInput1()
    elseif numb == "^" then
     setInput1()
    elseif numb == "rt" then
     setInput1()
    elseif numb == "H" then
     displayHelp()
    elseif numb == "F" then
     term.clear()
     redraw()
     drawFunctionsTable()
     drawExtraButtonsTable()
     fillTable()
     fillExtraFunctions()
     fillExtraButtonsTable()
    elseif numb == "=" then
     enterPress()
    end

    calc = calc .. numb
    term.setCursorPos(4, 4)
    if #calc < 14 then
     write(calc)
    else
     write(calc:sub(#calc-14))
    end
   end
  end
 end
end