ComputerCraft Calculator V2

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

fs.makeDir("temp")

createtemp = fs.open("/temp/calctemp", "w")
createtemp.writeLine(" ")
createtemp.close()

createtemp2 = fs.open("/temp/calctemp2", "w")
createtemp2.writeLine(" ")
createtemp2.close()

function editnum1(x)
    readline = fs.open("/temp/calctemp", "r")
    readnum1 = readline.readLine()
    readline.close()
    writenum1 = fs.open("/temp/calctemp", "w")
    writenum1.write(readnum1..x)
    writenum1.close()
end

function editnum2(y)
    readnum2 = fs.open("/temp/calctemp2", "r")
    tempnum2 = readnum2.readLine()
    readnum2.close()
    writenum2 = fs.open("/temp/calctemp2", "w")
    writenum2.write(tempnum2..y)
    writenum2.close()
end

    term.setTextColor(colors.yellow)
print("7  8  9  +")
print(" ")
print("4  5  6  -")
print(" ")
print("1  2  3  *")
print(" ")
print(".  0  =  /")
  decimal = "."
  add = " + "
  subtract = " - "
  multiply = " * "
  divide = " / "
  finished = false
  mathf = 0
  maths = 0
pos = 1
term.setTextColor(1)
    minus = "-"
negative = false
characters = 0

repeat
char = -5

  local event, button, mouseX, mouseY = os.pullEvent("mouse_click")
    if mouseX == 1 then
      if mouseY == 1 then
        char = 7
      elseif mouseY == 3 then
        char = 4
      elseif mouseY == 5 then
        char = 1
      elseif mouseY == 7 then
        char = 12
      end
    elseif mouseX ==  4 then
      if mouseY == 1 then
        char = 8
      elseif mouseY == 3 then
        char = 5
      elseif mouseY == 5 then
        char = 2
      elseif mouseY == 7 then
        char = 0
      end
    elseif mouseX == 7 then
      if mouseY == 1 then
        char = 9
      elseif mouseY == 3 then
        char = 6
      elseif mouseY == 5 then
        char = 3
      elseif mouseY == 7 and mathf == 1 then
        char = 14
        if mathf == 1 then
          finished = true
        end
      end
    elseif mouseX == 10 and characters ~= 0 then
      if mouseY == 1 then
        if mathf == 0 then
          mathf = -1
        end
      elseif mouseY == 3 then
 --       if pos == 1 and math == 0 then
 --         math = -5
        if mathf == 0 then
          mathf = -2
        end
      elseif mouseY == 5 then
        if mathf == 0 then
          mathf = -3
        end
      elseif mouseY == 7 then
        if mathf == 0 then
          mathf = -4
        end
      end
    end

if char >=0 or mathf < 0 then
    term.setCursorPos(pos, 9)
    if mathf < 0 and mathf ~= -5 then
            if mathf == -1 then
                    print(add)
                    maths = 1
            elseif mathf == -2 then
                    print(subtract)
                    maths = 2
            elseif mathf == -3 then
                    print(multiply)
                    maths = 3
            elseif mathf == -4 then
                    print(divide)
                    maths = 4
            end
        mathf = 1
        pos = pos + 2
    elseif math == -5 then
                    print("-")
                    negative = true
                    mathf = 0
                    char = 13

elseif char >= 0 and char ~= 12 and char ~= 14 then
    print(char)
    characters = 1
    if mathf == 0 and negative == false then
        editnum1(char)
    elseif mathf == 1 and negative == false then
        editnum2(char)
    elseif mathf == 0 and negative == true then
        editnum1("-")
        negative = false
        finalnegative = true
    end

elseif char == 12 and mathf == 0 then
    print(decimal)
    editnum1(".")
elseif char == 12 and mathf == 1 then
    print(decimal)
    editnum2(".")

elseif char == 14 then
    finished = true

end
pos = pos + 1
end
until finished == true

finalread1 = fs.open("/temp/calctemp", "r")
finalnum1 = finalread1.readLine()
finalread1.close()

finalread2 = fs.open("/temp/calctemp2", "r")
finalnum2 = finalread2.readLine()
finalread2.close()

term.setCursorPos(1, 10)
print("=")

if finalnum1 == nil or finalnum1 == " " then
        print("Please input two numbers")
        error()
end

if finalnum2 == nil or finalnum2 == " " then
        print("Please input two numbers.")
        error()
end

if maths == 4 and finalnum2*1 == 0 and finalnum1*1 ~= 0 then
        for error = 1, 10 do
            print("ERROR!!!!!"..math.random(1, 999999))
            sleep(0.5)
        end
        error()
elseif maths == 4 and finalnum2*1 == 0 and finalnum1*1 == 0 then
        print("Imagine that you have zero cookies and you split them evenly among zero friends. How many cookies does each person get? See? It doesn't make sense. And Cookie Monster is sad that there are no cookies, and you are sad that you have no friends.")
        error()
end

    if maths == 1 then
            print(finalnum1 + finalnum2)
    elseif maths == 2 then
            print(finalnum1 - finalnum2)
    elseif maths  == 3 then
            print(finalnum1 * finalnum2)
    elseif maths == 4 then
            print(finalnum1 / finalnum2)
    end

    if maths == 1  or maths == 2 then
  if finalnum1*1 == 0 or finalnum2*1 == 0 then
            print("That's some tough math.")
  end
    elseif maths == 3 or maths == 4 then
  if finalnum1*1 == 1 or finalnum2*1 == 1 then
            print("That's some tough math.")
  end
    end

fs.delete("/temp/calctemp")
fs.delete("/temp/calctemp2")

char = -24
mathf = 0
maths = 0


term.setCursorPos(1, 12)
print("Press enter to finish.")
quit = read()
shell.run("calculator")