Backend.java

/*

Jonathan Bajada 500798771
Ryan Woodworth 500752821
Manuel Oshana   500699021

This acts as the backend for the tix selling system.
Inputs are daily transaction file, event file, and accounts file
Outputs are new account file, and new event file.

meant to be run from command line:

javac Backend.java
java Backend

*/


import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.Scanner;

public class Backend {
  /**
   * @param args the command line arguments
   **/



  //Lines read from files
  static ArrayList<String> transactions = new ArrayList<String>();
  static ArrayList<String> accounts = new ArrayList<String>();
  static ArrayList<String> tickets = new ArrayList<String>();

  //Current users
  static ArrayList<String> sessionUsers = new ArrayList<String>();

  //Event & account names
  static ArrayList<String> eventNames = new ArrayList<String>();
  static ArrayList<String> users = new ArrayList<String>();
  


  //------------------------ Read & Write functions
    
  public static void readFiles() throws FileNotFoundException{
    //TODO Proper fatal error reporting to terminal (currently reports java error type without any parsing)
    
    /*
      Open and Read 3 Input Files
    */
    //Open and read transaction file
    try{
      File dt = new File(System.getProperty("user.dir") + "/transactionFile.txt"); // Daily Transaction File
      Scanner sc = new Scanner(dt); 
      while (sc.hasNextLine()){
        //System.out.println(sc.nextLine());
        transactions.add(sc.nextLine());
      }
      sc.close();
    } catch (Exception e){
      System.out.println(e);
      System.exit(0);
    }
    //Open and read account file
    try{
      File accountsFile = new File(System.getProperty("user.dir") + "/AccountFile.txt"); // Accounts File
      Scanner sc2 = new Scanner(accountsFile);
      while (sc2.hasNextLine()){ 
        //System.out.println(sc.nextLine());
        accounts.add(sc2.nextLine());
      }
      sc2.close();
    } catch (Exception e){
      System.out.println(e);
      System.exit(0);
    }
    //Open and read event file
    try{
      File ticketsFile = new File(System.getProperty("user.dir") + "/eventFile.txt");
      Scanner sc3 = new Scanner(ticketsFile);
      while (sc3.hasNextLine()){ 
        //System.out.println(sc.nextLine());
        tickets.add(sc3.nextLine());
      }
      sc3.close();
    } catch (Exception e){
      System.out.println(e);
      System.exit(0);
    }

    //Print Arrays after reading
    //System.out.println(transactions);
    //System.out.println(tickets);
    //System.out.println(accounts);

    //Get event and user names
    getEventNames();
    getAccountNames();
  } //Read 3 input files, use helper functions


  //TODO change terminal output for fatal error
  public static void writeFiles(){
    try{
      FileWriter newAccounts = new FileWriter("newAccounts.txt");
      FileWriter newEvents = new FileWriter("newEvents.txt");

      //Write new accounts file
      for(String a : accounts){
        newAccounts.write(a);
        if(accounts.indexOf(a) != accounts.size() - 1){
          newAccounts.write("\n");
        }
      }

      //Write new event files
      for(String e : tickets){
        newEvents.write(e);
        if(tickets.indexOf(e) != tickets.size() - 1){
          newEvents.write("\n");
        }
      }

      //Close FileWriters
      newAccounts.close();
      newEvents.close();

    } catch(Exception e){
      System.out.println(e);
    }
  }

  //-----------------






  //----------------- Helper functions
  
  public static void getEventNames(){
    for(String event : tickets){
      eventNames.add(event.substring(0, 18).trim());
    }
  } //Get all existing event names

  public static void getAccountNames(){
    for(String account : accounts){
      users.add(account.substring(0,15).trim());
    }
  } //Get all names of existing users
//----------------------








//---------------------- Transaction functions

//TODO check for existing user before adding
  public static void createUser(String transaction) throws FileNotFoundException{
    // split up the transaction string into substrings by whitespace
    String[] split = transaction.split("\\s+");
    /* First string is not used to create user, since its the code 01,
      split[1] is username
      split[2] is account type
      split[3] is credit
    */
    String account = split[1];
    
    for(int i = 0; i < (16 - split[1].length()); i++){ // Adding amount of whitespace needed to have proper formatting.
      account += " ";
    }
    account += split[2] + " " + split[3];
    System.out.println(account);
    accounts.add(account);
    System.out.println(accounts);
  } // Create new user
    
  //TODO delete all events associated with user
  public static void deleteUser(String transaction){
              String username = transaction.substring(3, 31).trim();
              accounts.remove(username);
  } //Delete user

  public static void refundUser(String transaction){
        String buyer = transaction.substring(3, 18).trim();
        String seller = transaction.substring(19,34).trim();
        double refundTemp = Double.parseDouble(transaction.substring(35,44).trim());

        //Update buyers credit
        for(String buyerName : accounts){
          if(buyerName.substring(0,15).trim().equals(buyer)){ //Find correct buyer account
            int index = accounts.indexOf(buyerName);  //Get index of account

            //Get user credit and apply changes
            Double creditTemp = Double.parseDouble(buyerName.substring(20,28).trim());
            creditTemp += refundTemp;

            //Formate new credit for update
            String newBalance = String.format("%.2f",creditTemp);
            newBalance = String.format("%9s", newBalance).replace(" ", "0");
            
            //Update user account
            accounts.set(index, buyerName.substring(0, 19) + newBalance);
          }
        }

        //Update sellers credit
        for(String sellerName : accounts){
          if(sellerName.substring(0,15).trim().equals(seller)){  //Find correct seller account
            int index = accounts.indexOf(sellerName); //Get index of account

            //Get user credit and apply changes
            Double creditTemp = Double.parseDouble(sellerName.substring(20,28).trim());
            creditTemp -= refundTemp;

            //Format new credit for update
            String newBalance = String.format("%.2f",creditTemp);
            newBalance = String.format("%9s", newBalance).replace(" ", "0");
            
            //Update user account
            accounts.set(index, sellerName.substring(0, 19) + newBalance);
          }
        }
  } //Refund user

  public static void createEvent(String transaction){
    Boolean add = true;

    String eventName = transaction.substring(3,21).trim();
    String sellerName = transaction.substring(22,37).trim();
    String tixQuantity = transaction.substring(38,41);
    String tixPrice = transaction.substring(42,48);

    //Check for duplicates
    for(String e : eventNames){
      if(eventName.equals(e)){
        add = false;
        //TODO Print constraint error
      }
    }

    //If no duplicates, add event
    if(add == true){
      eventNames.add(0, eventName); //Add to list of event names

      String newEventName = String.format("%-18s",eventName); //Format event name
      sellerName = String.format("%-15s",sellerName); //Format seller name
      String newEvent = newEventName + " " + sellerName + " " + tixQuantity + " " + tixPrice; //Create string

      tickets.add(0,newEvent);  //Add to list of events
    }
  } //Create a new event (Sell)

  //TODO complete and constraint error
  public static void buyTicket(String transaction)
  {
    
    String eventName = transaction.substring(3,21).trim();
    String sellerName = transaction.substring(22,36).trim();
    int ticketQuantity = Integer.parseInt(transaction.substring(36,40).trim());
    double price = Double.parseDouble(transaction.substring(40,46).trim());
    // Have to take money out of users account then change tickets remainin
    double total = price * ticketQuantity;
    int accountIndex;
    int eventIndex;
    // Updating seller account with the right amount of credit
    for(String account : accounts){
      if(sellerName == account){
        accountIndex = accounts.indexOf(account);
        // Going to split up the account string to update the amount of credit, then update accounts with the rebuilt version
        String accountName = account.substring(0, 17);
        double accountsCredit = Double.parseDouble(account.substring(18,27)) + total;
        accounts.set(accountIndex, accountName + accountsCredit);
      }
    }
    for(String event : eventNames){
      if(event == eventName){
        eventIndex = eventNames.indexOf(event);
        String nameAndSeller = event.substring(0,33);
        int quantity = Integer.parseInt(event.substring(33, 36)) - ticketQuantity;
        double eventPrice = Double.parseDouble(event.substring(37,43));
        eventNames.set(eventIndex, nameAndSeller + quantity + eventPrice);
      }

    }
    
    
  } //Buy tickets

  public static void addCredit(String transaction){
    // Split up the transaction string into substrings by whitespace
    String[] split = transaction.split("\\s+");
    int index;
    double newCredit;
    String updatedAccount;
    for(String account : accounts){

        if(account.substring(0, 15).contains(split[1])){ // if user from transaction matches a user in accounts
          index = accounts.indexOf(account);
          String[] accountSplit = account.split("\\s+");
          
          newCredit = Double.parseDouble(accountSplit[2]) + Double.parseDouble(split[3]);
          accountSplit[2] = Double.toString(newCredit);
          updatedAccount = accountSplit[0];
          for(int i = 0; i < (16 - accountSplit[1].length()); i++){ // Sorry for nested for loops 
            updatedAccount += " ";
          }
          updatedAccount += accountSplit[1] + " " + accountSplit[2];

          accounts.set(index, updatedAccount);
          System.out.println(updatedAccount);
          System.out.println(accounts);

        }

    }

  } // Add user credit

  //------------------------------







  //------------------------------  Main function
  public static void main(String[] args) throws FileNotFoundException {
    int currentUser = 0; //First user is the first user in sessionUser

    readFiles();  //Read the 3 input files
    
    //Find all logouts, make list of users from the day
    for (String transaction : transactions){
      if(transaction.startsWith("00")){
        String username = transaction.substring(3, 18).trim();
        sessionUsers.add(username);
      }
    }
 
    for (String transaction : transactions) {
      if(transaction.startsWith("01")){
			  createUser(transaction);
      }
      else if(transaction.startsWith("02")){
			  deleteUser(transaction);
      }
      else if(transaction.startsWith("03")){
        createEvent(transaction);
      }
      else if(transaction.startsWith("04")){
			  buyTicket(transaction);
      }
      else if(transaction.startsWith("05")){
			  refundUser(transaction);
      }
      else if(transaction.startsWith("06")){
        addCredit(transaction);
      }/*
      else if(transaction.startsWith("00")){
        currentUser++; //Once user logsout, update current user (index of sessionUser)
      }*/
    }

    //TODO write 2 output files (new events + new accounts; fill out method)
    writeFiles();
  }


  
}