termX, termY = term.getSize()
loged = nil

local customColors = {
        colors.red,    --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)

        rednet.open("top")
        rednet.send(54, inputLogin)
        senderId, message, distance = rednet.receive(5)
        if password == message 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
end

function successfulLogin()
        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