-- Function to check if a peripheral is connected and return it, or raise an error with a custom error message.
local function checkPeripheral(name, errorMessage)
   local peripheral = peripheral.find(name)
   assert(peripheral, errorMessage)
   return peripheral
end

-- Custom colors for button states
colorButtonOn = colors.lime
colorButtonOff = colors.gray

-- Initialize the monitor peripheral
mon = checkPeripheral("monitor", "Monitor not found.")
button = {}  -- Table to store button data

-- Function to clear the button table and clear the monitor screen.
function clearTable()
   button = {}
   mon.clear()
end

-- Function to add a button to the button table with its associated function and coordinates.
function setTable(name, func, xmin, xmax, ymin, ymax)
   button[name] = {}
   button[name]["func"] = func
   button[name]["active"] = false
   button[name]["xmin"] = xmin
   button[name]["ymin"] = ymin
   button[name]["xmax"] = xmax
   button[name]["ymax"] = ymax
end

-- Function to fill a button area with text and color.
function fill(text, color, bData)
   mon.setBackgroundColor(color)
   local yspot = math.floor((bData["ymin"] + bData["ymax"]) / 2)
   local xspot = math.floor((bData["xmax"] - bData["xmin"] - string.len(text)) / 2) + 1
   for j = bData["ymin"], bData["ymax"] do
      mon.setCursorPos(bData["xmin"], j)
      if j == yspot then
         for k = 0, bData["xmax"] - bData["xmin"] - string.len(text) + 1 do
            if k == xspot then
               mon.write(text)
            else
               mon.write(" ")
            end
         end
      else
         for i = bData["xmin"], bData["xmax"] do
            mon.write(" ")
         end
      end
   end
   mon.setBackgroundColor(colors.black)
end

-- Function to update the screen with button states.
function screen()
   local currColor
   for name, data in pairs(button) do
      local on = data["active"]
      if on == true then
         currColor = colorButtonOn
      else
         currColor = colorButtonOff
      end
      fill(name, currColor, data)
   end
end

-- Function to toggle a button's state and update the screen.
function toggleButton(name)
   for buttonName, data in pairs(button) do
       if buttonName ~= name and data["active"] then
           data["active"] = false
       end
   end
   button[name]["active"] = true
   screen()
end

-- Function to temporarily toggle a button's state (for visual feedback) and update the screen.
function flash(name)
   toggleButton(name)
   screen()
   sleep(0.25)
   toggleButton(name)
   screen()
end

-- Function to check if a click falls within any button's coordinates and execute its associated function.
function checkxy(x, y)
   for name, data in pairs(button) do
      if y >= data["ymin"] and y <= data["ymax"] then
         if x >= data["xmin"] and x <= data["xmax"] then
            if data["func"] then
               data["func"]()
            end
            return true
         end
      end
   end
   return false
end

-- Function to draw a colored box on the monitor.
function drawBox(xStart, yStart, xEnd, yEnd, color)
   local w, h = mon.getSize()
   xStart = math.max(1, xStart)
   xEnd = math.min(w, xEnd)
   yStart = math.max(1, yStart)
   yEnd = math.min(w, yEnd)
   for x = xStart, xEnd do
       mon.setBackgroundColor(color)
       mon.setCursorPos(x, yStart)
       mon.write(" ")
       mon.setCursorPos(x, yEnd)
       mon.write(" ")
   end
   for y = yStart + 1, yEnd - 1 do
       mon.setBackgroundColor(color)
       mon.setCursorPos(xStart, y)
       mon.write(" ")
       mon.setCursorPos(xEnd, y)
       mon.write(" ")
   end
end

-- Function to draw button boxes with a specified color.
function drawButtonBoxes(color)
   drawBox(2, 2, 78, 33, color)
end

-- Function to display centered text on the monitor.
function heading(text, y, bgColor)
   local w, h = mon.getSize()
   mon.setBackgroundColor(colors.black)
   mon.setCursorPos((w - string.len(text)) / 2 + 1, y)
   mon.write(text)
end