package authentication;
import java.security.MessageDigest;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;

public class ValidateCredentials {

private boolean isValid;
private String filePath;
private String credentialsFileName;

public ValidateCredentials() {
    filePath = "";

    isValid = false;
    credentialsFileName = "credentials";
}

public boolean isCredentialsValid(String userName, String passWord) throws Exception {
    String original = passWord;
    MessageDigest md = MessageDigest.getInstance("MD5");
    md.update(original.getBytes());
    byte[] digest = md.digest();
    StringBuffer sb = new StringBuffer();
    for (byte b : digest) {
        sb.append(String.format("%02x", b & 0xff));
    }

    System.out.println("");
    System.out.println("original:" + original);
    System.out.println("digested:" + sb.toString()); //sb.toString() is what you'll need to compare password strings

    isValid = readDataFiles(userName, sb.toString());

    return isValid;
}

public boolean readDataFiles(String userName, String passWord) throws IOException {
    FileInputStream fileByteStream1 = null; // File input stream
    FileInputStream fileByteStream2 = null; // File input stream

    Scanner inFS1 = null;                   // Scanner object
    Scanner inFS2 = null;                   // Scanner object

    String textLine = null;
    String textFileName = null;

    boolean foundCredentials = false;

    // Try to open file
    System.out.println("");
    System.out.println("Opening file " + credentialsFileName + ".txt");
    fileByteStream1 = new FileInputStream(filePath + "credentials.txt");
    inFS1 = new Scanner(fileByteStream1);

    System.out.println("");
    System.out.println("Reading lines of text.");

    while (inFS1.hasNextLine()) {
        textLine = inFS1.nextLine();
        //System.out.println(textLine);

        String[] words = textLine.split("\s");//splits the string based on whitespace

        if (words[0].equals(userName) && textLine.contains(passWord)) {
            foundCredentials = true;
            int last = words.length - 1;
            textFileName = words[last];
            break;
        }
    }

    // Done with file, so try to close it
    System.out.println("");
    System.out.println("Closing file " + credentialsFileName + ".txt");

    if (textLine != null) {
        fileByteStream1.close(); // close() may throw IOException if fails
    }

    if (foundCredentials == true) {
        // Try to open file
        System.out.println("");
        System.out.println("Opening file " + textFileName + ".txt");

        fileByteStream2 = new FileInputStream(filePath + textFileName + ".txt");
        inFS2 = new Scanner(fileByteStream2);

        System.out.println("");

        while (inFS2.hasNextLine()) {
            textLine = inFS2.nextLine();
            System.out.println(textLine);
        }

        // Done with file, so try to close it
        System.out.println("");
        System.out.println("Closing file " + textFileName + ".txt");

        if (textLine != null) {
            fileByteStream2.close(); // close() may throw IOException if fails
        }
    }

    return foundCredentials;
}

}

package authentication;

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;
import java.util.Scanner;


public class Authentication {
  public static void main(String args[]) {
    try {
        Scanner inputCreds;
        inputCreds = new Scanner(new File("src\authentication\credentials.txt"));
        String userCredentials[][] = new String[100][4];
        int count = 0;

        while (inputCreds.hasNextLine()) {
            userCredentials[count][0] = inputCreds.next();
            userCredentials[count][1] = inputCreds.next();

            String l[] = inputCreds.nextLine().split(""[ ]+");
            l[0] = l[0].trim();
            l[0] = l[0].replace(""", "");
            userCredentials[count][2] = l[0];
            userCredentials[count][3] = l[0].trim();
            count++;
        }

        Scanner input = new Scanner(System.in);
        boolean RUN = true;
        int tries = 0;

        while (RUN) {
            System.out.println("Welcome to your Zoo Account Authorization Screen.");
            System.out.println("Please select your option:");
            System.out.println("(1) - Log In.");
            System.out.println("(2) - Exit Program.");

            int ch = Integer.parseInt(input.nextLine().trim());

            if (ch == 1) {
                tries++;
                System.out.print("Username: ");
                String userName = input.nextLine();
                System.out.print("Password: ");
                String passWord = input.nextLine();

                MessageDigest md;
                md = MessageDigest.getInstance("MD5");
                md.update(passWord.getBytes());
                byte[] digest = md.digest();
                StringBuilder sb = new StringBuilder();
                for (byte b : digest) {
                    sb.append(String.format("%02x", b & 0xff));
                }
                String hPassword = sb.toString();

                boolean badCreds = true;
                for (int i = 0; i < count; i++) {
                    if (userName.contentEquals(userCredentials[i][0])) {
                        if (hPassword.contentEquals(userCredentials[i][1])) {
                            List<String> data = null;

                            switch (userCredentials[i][3]) {
                                case "zookeeper":
                                    data = Files.readAllLines(Paths.get("zookeeper.txt"), Charset.defaultCharset());
                                    break;
                                case "admin":
                                    data = Files.readAllLines(Paths.get("admin.txt"), Charset.defaultCharset());
                                    break;
                                case "veterinarian":
                                    data = Files.readAllLines(Paths.get("veterinarian.txt"), Charset.defaultCharset());
                                    break;
                                default:
                                    break;
                            }
                            if (data != null) {
                                for (String s : data) {
                                    System.out.println(s);
                                }
                            }
                            tries = 0;

                            System.out.println("n1) Logout.");
                            System.out.println("2) Exit.");

                            ch = Integer.parseInt(input.nextLine().trim());
                            if (ch == 2) {
                                RUN = false;
                            }
                            badCreds = false;
                            break;
                        }
                    }
                }
                if (badCreds) {
                    System.out.println("Invalid Username or password.");
                }
            } else {
                break;
            }
            if (tries == 3) {
                RUN = false;
                System.out.println("Too many incorrect attempts!");
            }
        }
    } catch (IOException | NumberFormatException | NoSuchAlgorithmException ex) {
    }
}
}