This script is an illustration of Object oriented programming in R.It simulates a simple core banking system in R

OOP in R,simulating a simple banking system

# This script simulates a simple core banking system in R.Its an illustration of Object oriented programming in R
CBS <- R6Class(classname = "CBS",public = list(
  accs = tibble("Full Name" = NA,"IDNo" = NA,'AccountNo' = NA,'AccountBalance' = NA,'LoanBalance' = NA),
  bank_name = NA,
  initialize = function(accs = NULL,bank_name) {
    self$bank_name = bank_name
    cat(paste(' --------- \n This is ',self$bank_name,'. \n --------- \n'))
  },
  create_account = function(FirstName=NULL,SecondName=NULL,IDNo=NULL) {
    FirstName = readline(prompt = "Enter FirstName: ")
    SecondName = readline(prompt = "Enter SecondName: ")
    IDNo = readline(prompt = "Enter IDNo: ")
    id_acc = private$account_setup(IDNo)
    account_details = tibble(
        "Full Name" = paste(FirstName,SecondName),
        "IDNo" = as.character(pluck(id_acc,'IDNo')),
        'AccountNo' = pluck(id_acc,'accno'),
        'AccountBalance' = 0,
        'LoanBalance' = 0
      )
    self$accs = bind_rows(self$accs,account_details) %>% filter(!is.na(IDNo))
    cat(sprintf("Hi %s, welcome to ABCBank.We look foward to doing business  with you!\nYour account number is %s",
                FirstName,account_details$AccountNo))
    self$get_services(acc = account_details$AccountNo)
    # return(invisible(account_details))
  },
  make_deposit = function(acc=NULL,Amount=NULL){
    acc = readline(prompt = "Enter acc ")
    Amount = as.numeric(readline(prompt = "Enter Amount "))
    private$check_acc(acc = acc,expr = {
      self$accs = self$accs %>% mutate(AccountBalance = ifelse(AccountNo == acc,AccountBalance+Amount,AccountBalance))
      cat(glue("Dear Customer,your deposit of Ksh {Amount} was received successfully.Your current balance is Ksh {
                   pull(filter(self$accs,AccountNo == acc),AccountBalance )}"))})
  },
  make_withdrawal = function(acc=NULL,Amount=NULL){
    acc = readline(prompt = "Enter acc ")
    Amount =  as.numeric(readline(prompt = "Enter Amount "))
    private$check_acc(acc = acc,expr = {
      info = filter(self$accs,AccountNo == acc)
      if ( (pull(info,AccountBalance) - 100) > Amount ) {
        self$accs <- self$accs %>% mutate(
          AccountBalance = ifelse(AccountNo == acc,AccountBalance - Amount,AccountBalance)
        )
      }else{
        message(paste(' ----------\n Dear ',pull(info,`Full Name`),',we are unable to process a your request due to low balance in your account.Please try a lower value'))
      }
    })
    
  },
  check_balance = function(acc=NULL){
    acc = readline(prompt = "Enter acc ")
    private$check_acc(acc = acc,expr = {
     balance =  self$accs %>% filter(AccountNo == acc) %>% pull(AccountBalance)
     message(glue("--------------\n Dear Customer,your account balance is Ksh {balance}.\n--------------"))
    })
  },
  # loans
  request_loan = function(acc=NULL,Amount=NULL){
    acc = readline(prompt = "Enter acc ")
    Amount =  as.numeric(readline(prompt = "Enter Amount "))
    private$check_acc(acc = acc,expr = {
      info = filter(self$accs,AccountNo == acc)
      if ( (pull(info,LoanBalance)) <= 0 ) {
        self$accs = self$accs %>% mutate(LoanBalance = ifelse(AccountNo == acc,Amount,LoanBalance))
        cat(glue("Dear Customer,your loan request of Ksh {Amount} was processed successfully.Your outstanding loan balance is Ksh {
                   pull(filter(self$accs,AccountNo == acc),LoanBalance )}"))
      }else{
        message(glue("Dear Customer,your loan request of Ksh {Amount} was not successfull.Please clear your outstanding loan balance of Ksh {
                   pull(filter(self$accs,AccountNo == acc),LoanBalance )}."))
      }
    })
  },
  repay_loan = function(acc=NULL,Amount=NULL) {
    acc = readline(prompt = "Enter acc ")
    Amount =  as.numeric(readline(prompt = "Enter Amount "))
    private$check_acc(acc = acc,expr = {
      info = filter(self$accs,AccountNo == acc)
      if ((pull(info,LoanBalance)) > 0 ) {
        self$accs = self$accs %>% mutate(LoanBalance = ifelse(AccountNo == acc,LoanBalance-Amount,LoanBalance),
                                         AccountBalance = ifelse((AccountNo == acc) & (LoanBalance<0),abs(LoanBalance)+AccountBalance,AccountBalance ),
                                         LoanBalance = ifelse(LoanBalance < 0 ,0,LoanBalance))
        if ( (pull(info,LoanBalance)) >= Amount ) {
          
          cat(glue("Dear Customer,your loan payment of Ksh {Amount} was processed successfully.Your outstanding loan balance is Ksh {
                   pull(filter(self$accs,AccountNo == acc),LoanBalance )}"))
        }else{
          cat(glue("Dear Customer,your loan payment of Ksh {Amount} was processed successfully.Your loan is cleared,extra amount of Ksh {abs((pull(info,LoanBalance)) - Amount)} was deposited in your transactional account"))
        }
      }else{
        message("Dear Customer,you do not have an existing loan.")
      }
    })
  },
  check_loan_balance = function(acc=NULL){
    acc = readline(prompt = "Enter acc ")
    private$check_acc(acc = acc,expr = {
      balance =  self$accs %>% filter(AccountNo == acc) %>% pull(LoanBalance)
      cat(glue("--------------\n Dear Customer,your loan account balance is Ksh {balance}.\n--------------"))
    })
  },
  # simulate USSD!
  get_services = function(acc = NULL) {
    if (is.null(acc)) {
      cat('Welcome to ABC Banking Services!\nSelect\n1:Create new account\n2:Deposit\n3:Withdraw\n4:Request Loan\n5:Repay Loan\n6:My Account Balance\n7:My Loan Balance')
      input <- readline(prompt="Enter here: ") 
      switch (as.character(input),
              "1" = self$create_account(),
              "2" = self$make_deposit(),
              "3" = self$make_withdrawal(),
              "4" = self$request_loan(),
              "5" = self$repay_loan(),
              "6" = self$check_balance(),
              "7" = self$check_loan_balance()
      )
    }else{
      cat(paste('-----------\nSelect\n1:Deposit\n2:Withdraw\n3:Request Loan\n4:Repay Loan\n5:My Account Balance\n6:My Loan Balance'))
      input <- readline(prompt="Enter here: \n--------------\n") 
      switch (as.character(input),
              "1" = self$make_deposit(),
              "2" = self$make_withdrawal(),
              "3" = self$request_loan(),
              "4" = self$repay_loan(),
              "5" = self$check_balance(),
              "6" = self$check_loan_balance()
      )
    }
   
  }), 
  private = list(
     account_setup = function(IDNo) {
    if (nrow(filter(self$accs,!is.na(IDNo)) > 0 )) {
      accno =  paste0("00",substr(paste0(sample(1:100, 12, replace=F),collapse = ""),1,9))
      while (accno %in% self$accs$AccountNo) {
        accno = as.character(rstudioapi::showPrompt(title = "IDNo",message = "Enter here"))
      }
    }else{
      accno =  paste0("00",substr(paste0(sample(1:100, 12, replace=F),collapse = ""),1,9))
    }
    # check if user exists
    if (nrow(filter(self$accs,!is.na(IDNo)) > 0 )) {
      while (IDNo %in% self$accs$IDNo) {
        IDNo = as.character(rstudioapi::showPrompt(title = "IDNo",message = "That ID already exists,Enter correct IDNo "))
      }
    }else{
      IDNo = IDNo
    }
    out = list(
      'IDNo' = IDNo,
      'accno' = accno
    )
    return(out)
  },
     check_acc = function(acc,expr={...}) {
       if (acc %in% self$accs$AccountNo) {
         expr
       }else{
         message("Account Supplied doesn't exist!")
       }
     }
))