local sg = peripheral.find("stargate")

local favAddresses = {
	{
		title = "",
		address = ""
	}
}

local event, p1, p2, p3 = nil
local screenSelection = 1
local screen = nil
local prevX, prevY = nil
local errorMessage = nil

function resetScreen()
	term.setBackgroundColor(colors.gray)
	term.setTextColor(colors.black)
	term.clear()
	term.setCursorPos(1, 1)
end

function PrintInline(text, x, y)
	term.setCursorPos(prevX + x, prevY + y)
	term.write(text)
	prevX = prevX + x
	prevY = prevY + y
end

function Print(text, x, y)
	term.setCursorPos(x, y)
	term.write(text)
	prevX = x
	prevY = y
end

function drawScreen(screenSettings)
	resetScreen()

	term.setBackgroundColor(colors.white)
	for i = 1, 3, 1 do
		term.setCursorPos(1, i)
		term.clearLine()
	end
	Print(screenSettings["title"], getCenterX(screenSettings["title"]), 2)
	term.setBackgroundColor(colors.gray)

	--For each option of a screen
	local line = getCenterY() - math.floor(tablelength(screenSettings["options"]) / 2)
	local curSel = 1
	for k, v in ipairs(screenSettings["options"]) do
		local label = v["option"]
		if curSel == screenSelection then
			term.setTextColor(colors.white)
			Print("[ ", getCenterX("[ " .. label .. " ]"), line)
			term.setTextColor(colors.black)
			PrintInline(label, string.len("[ "), 0, true)
			term.setTextColor(colors.white)
			PrintInline(" ]", string.len(label), 0, true)
			term.setTextColor(colors.black)
		else
			Print(label, getCenterX(label), line)
		end
		line = line + 1
		curSel = curSel + 1
	end
end

function getCenterX(text)
	local x,_ = term.getSize()
	return math.floor((x / 2) - (string.len(text) / 2))
end

function getCenterY()
	local _,y = term.getSize()
	return math.floor(y / 2)
end

function tablelength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

function tableAt(T, index)
	local i = 0
	for _, v in pairs(T) do
		if i == index then
			return v
		end
		i = i + 1
	end
end

function startup()
	screenSelection = 1
	screen = {
		title = "Stargate Control Program",
		options = {
			{
				option = "Dial Favorite",
				func = dialFavoriteScreen
			},
			{
				option = "Dial Manually",
				func = dialFavoriteScreen
			},
			{
				option = "Exit",
				func = exitProgram
			}
		}
	}
end

function dialFavoriteScreen()
	screenSelection = 1
	screen = {
		title = "Dial Favorites",
		options = {

		}
	}

	for k, v in ipairs(favAddresses) do
		table.insert(screen["options"],
		{
			option = v["title"],
			func = dialFav
		})
	end

	table.insert(screen["options"],
	{
		option = "Back",
		func = startup
	})
end

function dialFav()
	local destination = tableAt(favAddresses, screenSelection - 1)
	dial(destination["address"])
	startup()
end

function dial(address)
	if sg.dial(address) == "targetBusy" then
		local _, y = term.getSize()
		Print("Stargate is in use", 1, y)
		sleep(2)
	end
end

function exitProgram()
	os.reboot()
end

function awaitEvent()
	event, p1, p2, p3 = os.pullEvent()
end

function isSelectionChanged()
	if event == "key" then
		if p1 == keys.up then
			if screenSelection == 1 then
				screenSelection = tablelength(screen["options"])
			else
				screenSelection = screenSelection - 1
			end
		elseif p1 == keys.down then
			if screenSelection == tablelength(screen["options"]) then
				screenSelection = 1
			else
				screenSelection = screenSelection + 1
			end
		end
	end
end

function isSelctionSelected()
	if event == "key" then
		if p1 == keys.enter then
			tableAt(screen["options"], screenSelection - 1)["func"]()
		end
	end
end

startup()

while true do
	awaitEvent()
	isSelectionChanged()
	isSelctionSelected()
	drawScreen(screen)
end