-- File usage:
--
--  Just copy and paste this code on to some random file on a disk and create another startup file named "startup" on that disk.
--    In "startup" put (replace [NAME] with the filename you put this code into)
--      os.loadAPI("disk/[NAME]")"
--
--  Note if using Encryption: If you plan to use this code on different machines, BUT you want to use the an RFID card between them
--    (you have one machine for reading and one for writing), you MUST MUST MUST use the same disk, OR copy the
--    "key-Blowfish" file to every other disk you want to use with that RFID card with
--
--  Free software license: I am posting this under the GNU GPL (GNU General Public License), that is to say, you can
--    take this code and do whatever you want with it, but if you distrubte it, you must also do so under the GNU GPL.
--
--    I also ask you give credit to me as the original writer
--
--      --Angellus_Mortis
--

-- Returns a handle to a peripheral connect of a specificed type
-- Returns nil if peripheral of type is not found
-- Input:
--  type (string) : type of peripheral to return a handle for
local function getPeripheral(type)
  local sides = {"top", "bottom", "left", "right", "back"}
  local i = 1
  repeat
    if  peripheral.getType(sides[i]) == type then
      return peripheral.wrap(sides[i])
    end
    i = i + 1
  until i == 6
    return nil
end

-- Changes the color to write a quick message and then changes it back
-- Only changes color if term is in color
-- Input:
--  text (string)     : text to output in color
--  someColor (color) : color to output the text in
local function writeColorMessage(text, someColor)
  if term.isColor() then
    term.setTextColor(someColor)
  end
  term.write(text)
  if term.isColor() then
    term.setTextColor(colors.white)
  end
end

-- Callback for when scanning starts from reader
-- By default,
--  this looks for an attached montior (should be 2x1)
--  And just displays "ID Required"
--  Changes background to Cyan and text to black
--  Turns off signal to door (see onValidCard for more)
local function onScanStart()
  local screen = getPeripheral("monitor")

  -- turn off door signal
  redstone.setBundledOutput("top", 0)
  if not screen then
    -- Throw error to console if monitor was not found
    writeColorMessage("Error: ", colors.red)
    term.write("No Monitor Detected!")
    print()
  else
    -- Write message
    screen.setTextScale(1.8)
    screen.clear()
    screen.setCursorPos(1, 2)
    if screen.isColor() then
      screen.setTextColor(colors.black)
      screen.setBackgroundColor(colors.cyan)
    end
    screen.write("ID Required")
  end
end

-- Callback when an invalid card is thown from Reader
-- By default,
--  this looks for an attached montior (should be 2x1)
--  And just displays "ID Required" in black
--  displays "Not Authorized!" in red
--  Cyan background
local function onInvalidCard()
  local screen = getPeripheral("monitor")

  -- Throw error to console if monitor was not found
  if not screen then
    writeColorMessage("Error: ", colors.red)
    term.write("No Monitor Detected!")
    print()
  else
    -- Write message
    screen.setTextScale(1.4)
    screen.clear()
    screen.setCursorPos(4, 2)
    if screen.isColor() then
      screen.setTextColor(colors.black)
      screen.setBackgroundColor(colors.cyan)
    end
    screen.write("ID Required")
    screen.setCursorPos(3, 4)
    if screen.isColor() then
      screen.setTextColor(colors.red)
    end
    screen.write("Not Authorized!")
  end
end

-- Callback for when valid card is thrown from reader
-- By default,
--  this looks for an attached montior (should be 2x1)
--  And just displays "ID Required" in black
--  displays "Access Granted" in green
--  Cyan background
--
--  Sends white wire signal on top of the monitor
--  To set up a door lock, just connect a white wire to the top
--  then connect the wire to a door.
--  Also set up monitor so the user knows what is going on
local function onValidCard()
  local screen = getPeripheral("monitor")

  -- Throw error to console if monitor was not found
  if not screen then
    writeColorMessage("Error: ", colors.red)
    term.write("No Monitor Detected!")
    print()
  else
    -- Write message
    screen.setTextScale(1.4)
    screen.clear()
    screen.setCursorPos(4, 2)
    if screen.isColor() then
      screen.setTextColor(colors.black)
      screen.setBackgroundColor(colors.cyan)
    end
    screen.write("ID Required")
    screen.setCursorPos(3, 4)
    if screen.isColor() then
      screen.setTextColor(colors.green)
    end
    screen.write("Access Granted")

    --Open door
    redstone.setBundledOutput("top", 1)
  end
end

-- Global varibles
local data = {["useEncryption"] = true, ["encryptionType"] = "Blowfish", ["keySize"] = nil}

-- test if the frist character of a given string is the one supplied
-- Input:
--  testString (string)   : character to test for (only ONE character)
--  inputString (string)  : string to test against
local function checkFirstChar(testString, inputString)
  if string.lower(testString) == string.lower(string.sub(inputString, 1, 1)) then
    return true
  else
    return false
  end
end

-- Prints program header
-- Input:
--  isAdmin (bool)  : whether or not program is in admin mode
local function header(isAdmin, type)
  local title
  if not type then
    title = "RFID Writer/Reader"
  elseif type == "writer" then
    title = "RFID Writer"
  elseif type == "reader" then
    title = "RFID Reader"
  end
  term.clear()
  term.setCursorPos(1, 1)
  if isAdmin then
    writeColorMessage(title .. " - Admin Mode", colors.green)
    print()
  else
    writeColorMessage(title, colors.cyan)
    print()
  end
  print()
end

-- Returns a string of the encryption key to use to encrypt the RFID text with
-- Input:
--  encryptor (handle)  : handle to cryptographic accelerator
local function getKey(encryptor)
  local file = fs.open("disk/key-"..data["encryptionType"], "r")

  -- If the key has not been generated yet, generate it
  if not file then
    file = fs.open("disk/key-"..data["encryptionType"], "w")
    local key = encryptor.generateSymmetricKey(data["encryptionType"], data["keySize"])
    local keyEnc = key.encode()
    file.write(keyEnc)
    file.close()
    return keyEnc
  end

  local key = file.readLine()
  file.close()
  return key
end

-- Determines if text needs decrypted and then returns it
-- Input:
--  message (string)    : text possibly decrypted
--  encryptor (handle)  : handle to cryptographic accelerator
local function testForEncryption(message, encryptor)
  -- If using encryption..
  if data["useEncryption"] and encryptor then
    local key = encryptor.decodeKey(data["encryptionType"], getKey(encryptor))
    -- Attempt to decrypt the message
    local status, err = pcall(function() message = key.decrypt(data["encryptionType"], message) end)
    -- If failes, set message to empty string to force password check to fail
    if not status then
      message = ""
    end
  end

  return message
end

-- Determines if text needs to be encrypted or not and then returns it
-- Input:
--  text (string)       : text to be written
--  encryptor (handle)  : handle to cryptographic accelerator
local function testEncode(text, encryptor)
  if data["useEncryption"] and encryptor then
    -- Convert the string into an object
    local key = encryptor.decodeKey(data["encryptionType"], getKey(encryptor))
    text = key.encrypt(data["encryptionType"], text)
  end

  return text
end

local function resetScreen()
  term.setCursorPos(1,1)
  term.clear()
end


-- Main program for the writer
-- Input:
--  param (string)  : optional parameter for admin mode
function Writer(param)
  -- Writing Variables
  local label
  local text
  local writer = getPeripheral("rfid writer")

  -- Encryption vars
  local encryptor = getPeripheral("cryptographic accelerator")

  -- Admin related vars
  local admin = false
  local secretParam = '146790'
  -- Simply delete the password if you want to prompt the user for it
  local adminPassword = ''

  -- Test if admin is to run
  if param == secretParam then
      admin = true
      -- If auto mode is off, ask for admin password
      if (adminPassword == '') then
        header(true, "writer")
        term.write("Enter the admin password: ")
        if term.isColor() then
          term.setTextColor(colors.cyan)
        end
        adminPassword = read("*")
        if term.isColor() then
          term.setTextColor(colors.white)
        end
      end
    end

    -- If RFID writer is not connected
    while not writer do
      header(admin, "writer")
      term.write("No RFID Writer Connected! ")
      writeColorMessage(":(", colors.red)
      print()
      term.write("Please connect one and press ")
      writeColorMessage("ENTER", colors.green)
      print()
      local event, param1
      repeat
        event, param1 = os.pullEvent ("key")
      until param1 == 28
      writer = getPeripheral("rfid writer")
    end

    -- If no valid card is present
    while (not writer.isPresent()) or writer.isCoded() do
      header(admin, "writer")
      term.write("RFID Card is either missing or already coded ")
      writeColorMessage(":(", colors.red)
      print()
      term.write("Please insert a blank RFID card and press ")
      writeColorMessage("ENTER", colors.green)
      print()
      local event, param1
      repeat
        event, param1 = os.pullEvent ("key")
      until param1 == 28
    end

    header(admin, "writer")

    -- Set Disk Label
    term.write("Enter the label for the disk: ")
    if term.isColor() then
      term.setTextColor(colors.cyan)
    end
    label = read()
    if term.isColor() then
      term.setTextColor(colors.white)
    end


    if label == secretParam then
      return Writer(label)
    end

    -- Gets text to encode
    term.write("Enter text to write to RFID Card: ")
    if term.isColor() then
      term.setTextColor(colors.cyan)
    end
    text = read()
    if term.isColor() then
      term.setTextColor(colors.white)
    end

    -- Y-offset for any admin mode related messages
    local offset = 0

    print()
    print("Starting RFID Encoding...")

    if not admin then
      -- Encodes card
      writer.encode(testEncode(text, encryptor), label)
    else
      -- Passes in admin password
      writer.encode(testEncode(text, encryptor), label, adminPassword)
      -- Does not really test. Uses progress to determine if the password was successful
      term.write("Testing admin password...")
      offset = offset + 1
    end

    os.sleep(1)

    local progress = writer.getProgress()

    -- if Admin mode, display if password was successful
    if progress >= 0 and admin then
      offset = offset + 1
      term.write("..Invalid!")
      print()
      -- turn off admin mode so progress bar will show
      admin = false
    elseif admin then
      term.write("..Success")
      print()
      print()
    end

    -- if not admin mode (or password failed) show progress bar
    if not admin then
      term.setCursorPos(1, 8 + offset)
      local toDraw = 1
      -- adjust for varible screen width
      local w = term.getSize() - 10
      local frac = 1 / w
      -- Draw empty progress bar
      term.write("0% [")
      term.setCursorPos(5 + w, 8 + offset)
      term.write("] 100%")
      -- Draw progress line
      while progress >= 0 do
        term.setCursorPos(4 + toDraw, 8 + offset)
        while progress >= (toDraw * frac) do
          term.write("-")
          toDraw = toDraw + 1
        end
        os.sleep(1)
        progress = writer.getProgress()
      end
      -- make sure progress bar gets filled ;)
      while (toDraw * frac) <= 1 do
        term.write("-")
        toDraw = toDraw + 1
      end
      print()
    end

    print("Text successfully written to card.")
    print()
    term.write("Press ")
    writeColorMessage("ENTER", colors.green)
    term.write(" to exit...")
    local event, param1
    repeat
      event, param1 = os.pullEvent ("key")
    until param1 == 28
    resetScreen()

    Writer()
end

-- Main program for the reader
function Reader()
  -- Reading Varibles
  local reader = getPeripheral("rfid reader")
  local allowOtherCards = false
  local detected = 0
  local valid = false
  local password = ""


  -- Encryption vars
  local encryptor = getPeripheral("cryptographic accelerator")

  -- If RFID reader is not connected
  while not reader do
    header(false, "reader")
    print("No RFID Reader Connected! :(")
    term.write("Please connect one and press ")
    writeColorMessage("ENTER", colors.green)
    print()
    local event, param1
    repeat
      event, param1 = os.pullEvent ("key")
    until param1 == 28
    reader = getPeripheral("rfid reader")
  end

  -- If password is not set, prompt user to provide a card with one on it
  -- IMPORTANT! Only one RFID card can be present when setting password or else
  --       the wrong password may be set
  while password == "" do
    header(false, "reader")
    print("Password not set. Verify the card with the valid ")
    print("password on it is in range and is the ONLY card ")
    term.write("within range and press ")
    writeColorMessage("ENTER", colors.green)
    print()
    local event, param1
    repeat
      event, param1 = os.pullEvent ("key")
    until param1 == 28
    print()
    print("Scanning for card...")
    reader.scan()
    -- Repeat pull event until done scanning
    repeat
      event, param1 = os.pullEvent()
      if (event == "rfid_detected") then
        print("Card found. Trying to set password...")
        password = testForEncryption(param1, encryptor)

        if not (password == "") then
          -- Some stuff for the user
          print("Password set")
          print("Starting reader...")
          sleep(1)
        end
      -- Could not set password
      elseif event == "rfid_scan_done" and password == "" then
        if data["useEncryption"] then
          print("No card found or unable to decrypt password!")
          print()
          print("Make sure you are using the same encryption key for the reader and writer.")
          sleep(5)
        else
          print("No card found!")
          sleep(2)
        end
      end
    until event == "rfid_scan_done" or not (password == "")
  end

  -- ASk the user if they want to still throw a valid card event when there
  -- are other invalid cards around
  local doRepeat = true
  repeat
    header(false, "reader")
    print("Do you want to throw valid card with other invalid cards around?")
    term.write("Enter yes/[no]: ")
    if term.isColor() then
      term.setTextColor(colors.cyan)
    end
    local usrInp = read()
    if term.isColor() then
      term.setTextColor(colors.white)
    end
    if checkFirstChar('n', usrInp) or usrInp == '' then
      allowOtherCards = false
      doRepeat = false
    elseif checkFirstChar('y', usrInp) then
      allowOtherCards = true
      doRepeat = false
    end
  until not doRepeat

  -- Start reading loop
  while true do
    header(false, "reader")
    valid = false
    detected = 0

    print("Scanning for cards...")
    print()
    reader.scan()
    onScanStart()

    local event, message
    repeat
      event, message = os.pullEvent()

      if event == "rfid_detected" then
        print("An RFID Card was detected.")
        term.write("Testing password...")

        if testForEncryption(message, encryptor) == password then
          term.write("..Success")
          if ((not allowOtherCards) and detected == 0) or allowOtherCards then
            valid = true
          end
        else
          term.write("..Invalid")
          if not allowOtherCards then
            valid = false
          end
        end
        print()
        print()
        detected = detected + 1
      end
    until event == "rfid_scan_done"

    if detected == 0 then
      print("No cards found.")
    elseif valid then
      print("Valid password!")
      onValidCard()
    elseif not allowOtherCards then
      print("Invalid password or other cards nearby!")
      onInvalidCard()
    else
      print("Invalid password!")

      onInvalidCard()
    end
    os.sleep(5)
  end

  Reader()
end

function runRFID()
  local reader = getPeripheral("rfid reader")
  local writer = getPeripheral("rfid writer")

  -- If RFID writer/reader is not connected
  while not reader and not writer do
    header(false)
    print("No RFID Writer/Reader Connected! :(")
    term.write("Please connect one and press ")
    writeColorMessage("ENTER", colors.green)
    print()
    local event, param1
    repeat
      event, param1 = os.pullEvent ("key")
    until param1 == 28
    reader = getPeripheral("rfid reader")
    writer = getPeripheral("rfid writer")
  end

  if reader and writer then
    local doRepeat = true
    repeat
      header(false)
      print("Both a reader and writer connected.")
      term.write("Enter [reader]/writer: ")
      if term.isColor() then
        term.setTextColor(colors.cyan)
      end
      local usrInp = read()
      if term.isColor() then
        term.setTextColor(colors.white)
      end
      if checkFirstChar('r', usrInp) or usrInp == '' then
        Reader()
        doRepeat = false
      elseif checkFirstChar('w', usrInp) then
        Writer()
        doRepeat = false
      end
    until not doRepeat
  elseif reader then
    Reader()
  elseif writer then
    Writer()
  end
end

function startup()
  local reader = getPeripheral("rfid reader")
  local writer = getPeripheral("rfid writer")
  local encryptor = getPeripheral("cryptographic accelerator")
  header(false)
  writeColorMessage("Booting.", colors.magenta)
  sleep(1)
  writeColorMessage(".", colors.magenta)
  sleep(1)
  writeColorMessage(".", colors.magenta)
  print()

  if encryptor then
    writeColorMessage("Encryptor found", colors.cyan)
    print()
    print("Using encryption...")
    data["useEncryption"] = true
  else
    writeColorMessage("No encryptor found", colors.red)
    print()
    print("Turning off encryption...")
    data["useEncryption"] = false
  end
  sleep(1)

  if not reader and not writer then
    writeColorMessage("Reader and writer missing", colors.red)
    print()
    print("Prompting to place one...")
  elseif reader and writer then
    writeColorMessage("Reader ", colors.green)
    term.write("and ")
    writeColorMessage("Writer ", colors.yellow)
    term.write("both found")
    print()
    print("Prompting which to use...")
  elseif reader then
    writeColorMessage("Reader found", colors.green)
    print()
    print("Starting reader...")
  elseif writer then
    writeColorMessage("Writer found", colors.yellow)
    print()
    print("Starting writer...")
  end
  sleep(1)

  runRFID()
end

function os.pullEvent(_sFilter)
   local event = { os.pullEventRaw(_sFilter) }
   if event[1] == "terminate" then
     runRFID()
   end
   return unpack(event)
 end

startup()