Bank Host v2

modem = peripheral.find("modem")

if not modem then
  print("No modem")
end

modem.open(1024)

function getMoney(user, key)
  if user == nil or key == nil then
    return "Failed."
  end

  if fs.exists("account/"..user) then
    account = fs.open("account/"..user, "r")
    line = account.readLine()
    line2 = account.readLine()
    account.close()
  else
    return "Failed"
  end

  if key == line then
    return line2
  else
    return "Failed"
  end
end

function transfer(give, take, gkey, amountf)
  if give == nil or take == nil or gkey == nil or amountf == nil then
    return "Failed."
  end

  if not fs.exists("account/"..give) or not fs.exists("account/"..take) then
    return "Failed."
  end

  giverf = fs.open("account/"..give, "r")
  givekey = giverf.readLine()
  giveramount = giverf.readLine()
  giverf.close()

  takef = fs.open("account/"..take, "r")
  takekey = takef.readLine()
  takeramount = takef.readLine()
  takef.close()

  if amountf > giveramount then
    return "Not enough money."
  end

  if gkey == givekey then
    newamountg = giveramount - amountf
    newamountf = takeramount + amountf

    giverf = fs.open("account/"..give, "w")
    giverf.writeLine(givekey)
    giverf.writeLine(newamountg)
    giverf.close()

    takef = fs.open("account/"..take, "w")
    takef.writeLine(takekey)
    takef.writeLine(newamountf)
    takef.close()

    return "Completed!"

  else
    return "Failed."
  end
end

function makeKey()
  a = math.random(0, 9)
  b = math.random(0, 9)
  c = math.random(0, 9)
  d = math.random(0, 9)
  e = math.random(0, 9)
  f = math.random(0, 9)
  g = math.random(0, 9)
  h = math.random(0, 9)
  i = math.random(0, 9)
  j = math.random(0, 9)

  newkey = a..b..c..d..e..f..g..h..i..j
  return newkey

end

function newUser(user, key)
  d = fs.exists("account/"..user)

  if d == false then
    file = fs.open("account/"..user, "w")
    file.writeLine(key)
    file.writeLine(0)
    file.close()

    return "Completed"
  else
    return "UE"
  end
end

function receive()
  event = {os.pullEvent("modem_message")}

  return event[5]
end

function broadcast(message_trans)
  modem.transmit(1024, 1024, message_trans)
end

while true do
  mes = receive()

  request = textutils.unserialise(mes)

  if request["type"] == "getmoney" then
    money = getMoney(request.user, request.key)

    broadcast(money)
  elseif request.type == "newuser" then
    newkey = makeKey()
    result = newUser(request.target, newkey)

    newac = {}
    newac["result"] = result
    newac["key"] = newkey

    broadcast(textutils.serialize(newac))
  elseif request["type"] == "transfer" then
    result = transfer(request.user, request.target, request.key, request.amount)

    broadcast(result)
  end
end