termX, termY = term.getSize()
loged = nil
local customColors = {
	colors.blue,	--Background color
	colors.white,	--Login field color
	colors.black	--Text color
 }

function drawBackground()
	term.setBackgroundColor(customColors[1])
	term.clear()
	term.setCursorPos(1,1)
end

function drawLoginField()

	paintutils.drawLine(termX/2 - 10, termY/2 - 3, termX/2 + 10, termY/2 - 3, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 - 1, termX/2 + 10, termY/2 - 1, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 + 1, termX/2 - 5, termY/2 + 1, customColors[2]) paintutils.drawLine(termX/2 + 9, termY/2 + 1, termX/2 + 10, termY/2 + 1, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2, termX/2 + 10, termY/2, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 + 2, termX/2 + 10, termY/2 + 2, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 - 4, termX/2 + 10, termY/2 - 4, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 - 2, termX/2 - 2, termY/2 - 2, customColors[2]) paintutils.drawLine(termX/2 + 9, termY/2 - 2, termX/2 + 10, termY/2 - 2, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 + 3, termX/2 + 10, termY/2 + 3, customColors[2])
	paintutils.drawLine(termX/2 - 10, termY/2 + 4, termX/2 + 10, termY/2 + 4, customColors[2])

	term.setTextColor(customColors[3])
	term.setCursorPos(termX/2 - 4, termY/2 - 4)
	term.write("Login GUI")
	term.setCursorPos(termX/2 - 7, termY/2 - 2)
	term.write("Login:")
	term.setCursorPos(termX/2 - 10, termY/2 + 1)
	term.write("Password:")
end

function loginFunction()
	term.setBackgroundColor(customColors[1])
	term.setCursorPos(termX/2 - 1, termY/2 - 2)
	local inputLogin = input(nil, 10)
	term.setCursorPos(termX/2 - 1, termY/2 + 1)
	local inputPassword = input("*", 10)
	local Table = findUser(inputLogin)

	if Table ~= nil then
		local user = textutils.unserialize(Table)

		if inputLogin == user.login and inputPassword == user.password then
			term.setCursorPos(termX/2 - 8, termY/2 + 6)
			term.setTextColor(colors.green)
			term.write("Successful login")
			sleep(2)
			successfulLogin()
		else
			term.setCursorPos(termX/2 - 9, termY/2 + 6)
			term.setTextColor(colors.red)
			term.write("Incorrect password")
			sleep(2)
			start()
		end
	else
		term.setCursorPos(termX/2 - 8, termY/2 + 6)
		term.setTextColor(colors.red)
		term.write("User not found")
		sleep(2)
		start()
	end
end

function successfulLogin()
	loged = user
	term.setBackgroundColor(colors.black)
	term.clear()
	term.setCursorPos(1,1)
end

function input( _sReplaceChar, charLimit, _tHistory )
	term.setCursorBlink( true )

	local charNum = 0
    	local sLine = ""
	local nHistoryPos = nil
	local nPos = 0
	if _sReplaceChar then
		_sReplaceChar = string.sub( _sReplaceChar, 1, 1 )
	end

	local w, h = term.getSize()
	local sx, sy = term.getCursorPos()

	local function redraw( _sCustomReplaceChar )
		local nScroll = 0
		if sx + nPos >= w then
			nScroll = (sx + nPos) - w
		end

		term.setCursorPos( sx, sy )
		local sReplace = _sCustomReplaceChar or _sReplaceChar
		if sReplace then
			term.write( string.rep(sReplace, string.len(sLine) - nScroll) )
		else
			term.write( string.sub( sLine, nScroll + 1 ) )
		end
		term.setCursorPos( sx + nPos - nScroll, sy )
	end

	while true do
		local sEvent, param = os.pullEvent()
		if sEvent == "char" then
			if charNum ~= charLimit then
				sLine = string.sub( sLine, 1, nPos ) .. param .. string.sub( sLine, nPos + 1 )
				nPos = nPos + 1
				charNum = charNum + 1
				redraw()
			else
				break
			end

		elseif sEvent == "key" then
		    if param == keys.enter then
				-- Enter
				break

			elseif param == keys.left then
				-- Left
				if nPos > 0 then
					nPos = nPos - 1
					redraw()
				end

			elseif param == keys.right then
				-- Right
				if nPos < string.len(sLine) then
					nPos = nPos + 1
					redraw()
				end

			elseif param == keys.up or param == keys.down then
                -- Up or down
				if _tHistory then
					redraw(" ");
					if param == keys.up then
						-- Up
						if nHistoryPos == nil then
							if #_tHistory > 0 then
								nHistoryPos = #_tHistory
							end
						elseif nHistoryPos > 1 then
							nHistoryPos = nHistoryPos - 1
						end
					else
						-- Down
						if nHistoryPos == #_tHistory then
							nHistoryPos = nil
						elseif nHistoryPos ~= nil then
							nHistoryPos = nHistoryPos + 1
						end
					end

					if nHistoryPos then
                    	sLine = _tHistory[nHistoryPos]
                    	nPos = string.len( sLine )
                    else
						sLine = ""
						nPos = 0
					end
					redraw()
                end
			elseif param == keys.backspace then
				-- Backspace
				if nPos > 0 then
					redraw(" ");
					sLine = string.sub( sLine, 1, nPos - 1 ) .. string.sub( sLine, nPos + 1 )
					nPos = nPos - 1
					charNum = charNum - 1
					redraw()
				end
			elseif param == keys.home then
				-- Home
				nPos = 0
				redraw()
			elseif param == keys.delete then
				if nPos < string.len(sLine) then
					redraw(" ");
					sLine = string.sub( sLine, 1, nPos ) .. string.sub( sLine, nPos + 2 )
					redraw()
				end
			elseif param == keys["end"] then
				-- End
				nPos = string.len(sLine)
				redraw()
			end
		end
	end

	term.setCursorBlink( false )
	term.setCursorPos( w + 1, sy )
	print()

	return sLine
end

function start()
	drawBackground()
	drawLoginField()
	loginFunction()
end

function findUser(name)
	local list = fs.open("/Users/list", "r")
	if list then
		local curLine = list.readLine()

		while curLine ~= name do
			curLine = list.readLine()
			if curLine == nil then
				return nil
			end
		end
		if curLine == name then
			local userTable = list.readLine()
			list.close()
			return userTable
		end
	else
		generateUserList()
	end
end

function generateUserList()
	if not fs.isDir("Users") then
		fs.makeDir("Users")
	end

	local list = fs.open("Users/list", "w")
	local defaultUser = {login="login", password="password"}
	list.writeLine("login")
	list.writeLine(textutils.serialize(defaultUser))

end

--Starts the program
start()

--Additional functions(Not working yet...)

function register(name, password)
	local list

	if not fs.isDir("Users") then
		fs.makeDir("Users")
	end

	if not fs.exists("Users/list") then
		list = fs.open("Users/list", "w")
	end

	list.writeLine(name)
	list.writeLine("= {login=" .. name .. "," .. "password=" .. password .. "}")
	list.close()
end

function getLogedUserName()
	if loged ~= nil then
		return loged.login
	else
		return "No user loged-in"
	end
end

function getLogedPassword()
	if loged ~= nil then
		return loged.password
	else
		return "No user loged-in"
	end
end