local monitor = {}

-- [[ Requires ]]

local computer = require("computer")
local component = require("component")

local event = require("event")
local thread = require("thread")

-- [[ Constants ]]

local gpu = component.gpu
local screen = component.screen

local resolutions = {
  { 50, 16 },
  { 80, 25 },
  { 160, 50 },
}

-- [[ Variables ]]

-- [[ Local functions ]]

local function calculateOptimalResolution()
  local monitorWidth, monitorHeight = screen.getAspectRatio()
  local ar = monitorWidth / monitorHeight

  local screenWidth, screenHeight = monitor.getResolutionFromTier(monitor.getScreenTier())

  local gpuMaxWidth, gpuMaxHeight = monitor.getResolutionFromTier(monitor.getGPUTier())
  local maxWidth = math.min(screenWidth, gpuMaxWidth)
  local maxHeight = math.min(screenHeight, gpuMaxHeight)

  if ar == 1.5 then
    return maxWidth, maxHeight
  end

  local height = maxHeight
  local width = ar * 2 * height

  if width > maxWidth then
    local perc = width / maxWidth
    height = height * (1 / perc)
    width = ar * 2 * height
  end

  return width, height
end

-- Works for gpu and screen
local function getTier(device)
  local info = computer.getDeviceInfo()[device.address]

  -- width is the bit depth
  if info.width == "1" then
    return 1
  elseif info.width == "4" then
    return 2
  elseif info.width == "8" then
    return 3
  end
end

-- [[ Exported functions ]]

monitor.getGPUTier = function()
  return getTier(gpu)
end

monitor.getScreenTier = function()
  return getTier(screen)
end

monitor.getResolutionFromTier = function(tier)
  return resolutions[tier][1], resolutions[tier][2]
end

monitor.fill = function()
  local w,h = calculateOptimalResolution()
  print(w, h)
  gpu.setResolution(calculateOptimalResolution())
end

monitor.test = function()
  local listener = function(_, _, type)
    if type == "screen" then
      monitor.fill()
      require("term").clear()
      gpu.setBackground(0xFFFFFF)
      local w,h = gpu.getResolution()
      gpu.set(1,1,(" "):rep(w))
      gpu.set(1,1,(" "):rep(h), true)
      gpu.set(w,1,(" "):rep(h), true)
      gpu.set(1,h,(" "):rep(w))
      gpu.setBackground(0x000000)
      print(w, h)
    end
  end

  event.listen("component_added", listener)
  event.listen("component_removed", listener)
  -- allows us to press ctrl+c to exit cleanly
  event.pull("interrupted")
  event.ignore("component_added", listener)
  event.ignore("component_removed", listener)
end

-- [[ Exporting ]]

return monitor

-- [[ EOF ]]