Global Banking System - Server Script

--Global Banking Main Server
--this program manages the Transactions and Information of all Accounts on the server
--this is for CC Tweaked 1.16.5 for minecraft


local Misc = nil
local BankingProtocol = 8452
local AccountBalance = nil
local ContactedID = nil
local SelectedAccount = nil
local AccountKey = nil
local CryptionCharacter_Base = ["space","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","0","1","2","3","4","5","6","7","8","9","\n","_"]
local CryptionCharacter_Locked = ["00","01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31","32","33","34","35"]
local EncryptedData = nil

start()

function start()
  Standby()
end

function Standby()
  ContactedID = nil
  AccountBalance = nil
  AccountKey = nil
  SelectedAccount = nil
  EncryptedData = nil
  rednet.open()
  rednet.host(8452,"BankingServer")
  local DATA = nil
  repeat
    local id, message, protocol = rednet.receive()
  until protocol == BankingProtocol
  ContactedID = id
  if message == "NewAccount" then
    repeat
      local id, message, protocol = rednet.receive()
    until id == ContactedID and protocol == BankingProtocol
    SelectedAccount = message
    if fs.exists("Account_"..SelectedAccount) == true then
      rednet.send(ContactedID,"Denied",8452)
      Standby()
    else
      local BankName = "n"
      AccountKey = rng(2,9)
      local file = fs.open("Account_"..SelectedAccount,"w")
      file.writeLine(SelectedAccount)
      file.writeLine(AccountKey)
      file.writeLine(BankName)
      file.writeLine(os.date(IRL))
      file.writeLine(ContactedID)
      file.writeLine(0)
      file.close()
      rednet.send(AccountKey)
      rednet.send(BankName)
      Standby()
    end
  else
    DATA = message
    repeat
      local id, message, protocol = rednet.receive()
    until id == ContactedID and protocol == BankingProtocol
    SelectedAccount = message
    FindAccount(account)
    Encryption_TypeB(DATA,"Decrypt")
    FindAccount(SelectedAccount)
    local Method == EncryptedData
    if Method.substring("r_",1,2) == true then
      Encryption_TypeB(AccountBalance,"Encrypt")
      rednet.send(ContactedID,EncryptedData,8452)
    elseif Method.substring("t_",1,2) == true then
      repeat
        local id, message, protocol = rednet.receive()
      until id == ContactedID and protocol == BankingProtocol
      local TargetAccount = message
      FindAccount(TargetAccount,"n")
      if Misc == false then
        rednet.send(ContactedID,"Account Not Found",8452)
        Standby()
      else
        rednet.send(ContactedID,"Account Found",8452)
        repeat
          local id, message, protocol = rednet.receive()
        until id == ContactedID and protocol == BankingProtocol
        if AccountBalance - message > -1 then
          rednet.send(ContactedID,"Accepted",BankingProtocol)
          EditBalance(SelectedAccount,message*-1)
          EditBalance(TargetAccount,message)
        else
          rednet.send(ContactedID,"Denied",BankingProtocol)
          Standby()
        end
      end
    end
  end
end

function EditBalance(Account,Action)
  local file = fs.open("Account_"..Account,"a")
  file.setCursorPos(1,6)
  local balance = file.readLine(6)
  file.clearLine(6)
  file.writeLine(balance+Action)
  file.close()
end

function FindAccount(account,save)
  if save == "n" then
    if fs.exists("Account_"..account) == true then
      Misc = true
    else
      Misc = false
    end
  else
    local File = fs.open("Account_"..account,"r")
    AccountKey = File.readLine(2)
    AccountBalance = File.readLine(6)
    File.close()
  end
end

function Encryption_TypeB(data,mode)
  data = string.lowerCase(data)
  local Result = ""
  if mode == "Encrypt" then
    Result = "B_"
    for i = 1, #data.bytes do
      local n = 1
      for n = 1, #CryptionCharacter_Base do
        if substring(data,i,i) == CryptionCharacter_Base[n] then
          Result = Result..CryptionCharacter_Locked[n+AccountKey]
        end
      end
    end
    EncryptedData = Result
  elseif mode == "Decrypt" then
    Result = ""
    for i = 1, #data.bytes do
      local n = 1
      for n = 1, #CryptionCharacter_Base do
        if substring(data,i,i) == CryptionCharacter_Locked[n] then
          if CryptionCharacter_Base[n-AccountKey] == "space" then
            Result = Result.." "
          else
            Result = Result..CryptionCharacter_Base[n-AccountKey]
          end
        end
      end
    end
    EncryptedData = Result
  end
end