Entropy

package edu.missouriwestern.noynaert.csc254;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

/**
 * This program calculates entropy of passwords, and checks to see if passwords
 * are on a list of common passwords.
 *
 * @author YOUR NAME
 * @since 2018/10/09
 */
public class Entropy {
    static final String AUTHOR = "YOUR NAME";

    public static void main(String[] args) {
        String fileName = getFileNameFromArgs(args);
        int n = 0;
        try {
            Scanner input = new Scanner(new File(fileName));
            System.out.printf("%8s %8s %8s %8s %8s %8s %s %s\n",
                    "Length", "Upper", "Lower", "Digits", "Symbols", "Range", "Entropy", "Pass Phrase");
            while(input.hasNextLine()) {
                String line = input.nextLine().trim();
                String symbols = "`~!@#$%^&*()-_=+[{\\]}|;:'\",<.>/?";
                boolean hasUpper = hasUpper(line);
                boolean hasLower = hasLower(line);
                boolean hasDigit = hasDigit(line);
                int length = line.length();
                int countSymbols = countSymbols(line,symbols);
                int range=range(line,symbols);
                int entropy = calculateEntropy(range,line);
                System.out.printf("%8d %8b %8b %8b %8d %8d %8d %s\n",
                        length, hasUpper, hasLower, hasDigit, countSymbols, range,entropy, line);
                n++;
            }
            input.close();
        } catch (FileNotFoundException e) {
            System.err.printf("The file \"%s\" does not exist.", fileName);
            System.exit(1);
        }

        System.out.printf("\nRecords processed: %d\n", n);
        System.out.println("Programmed by " + AUTHOR);
    }
    public static int calculateEntropy(int range, String word){
        //e=log2(r^(L-1)
        double power=word.length()-1;
        double tobeLogged=Math.pow((double)range, power);
        double e=Math.log(tobeLogged)/Math.log(2.);
        return (int)e;


    }
    public static int countSymbols(String word, String symbols){
        int result = 0;
        for(int i=0; i<symbols.length();i++)
            if(containsSymbol(word, symbols.charAt(i)))
                result++;
            return result;
    }
    public static boolean containsSymbol(String word, char symbol){
        boolean result = (word.indexOf(symbol)>-1);
        return result;

    }

    public static boolean hasDigit(String word){
        boolean result = word.matches(".*[0-9].*");
        return result;
    }
    public static boolean hasLower(String word){
        boolean result = word.matches(".*[a-z].*");
        return result;
    }
    public static boolean hasUpper(String word) {
        boolean result = word.matches(".*[A-Z].*");
        return result;
    }

    /**
     * If the args array is empty, then the file name is "input.txt"
     * If the args array is not empty, then the file name is set to args[0]
     *
     * @param args  An array of strings.  Normally this will be args from the main(String[] args) method.
     * @return A potential file name.  A file with the corresponding name is not guaranteed to exist.
     */
    public static String getFileNameFromArgs(String[] args) {
        String fileName = (args.length==0) ? "input.txt" : args[0];
        return fileName;
    }

    /**
     * Calculates the base 10 log of a number
     *
     * @param x  A real number.  The number should be positive
     * @return   The log<sub>10</sub> value of x
     */
    public static double log10(double x) {
        double result = Math.log(x) / Math.log(10);
        return result;
    }

    /**
     * @TODO Fill this in
     *
     * @param x
     * @return
     */
    public static double log2(double x){
        double result = Math.log(x) / Math.log(2.);
        return result;
    }

    /**
     * Calculates the range of a string.  The string s is scanned.
     * The range is initially 0.
     * <pre>
     *    Add 26 to the range if the string contains at least 1 upper case letter
     *    Add 26 to the range if the string contains at least 1 lower case letter
     *    Add 10 to the range if the string contains at least 1 digit
     *    Add 1 to the range for each of the special characters in
     *            "`~!@#$%^&*()-_=+[{]}\|;:'",<.>/?</.>"
     * </pre>

     */
    public static int range(String word, String symbols){
        int result = 0;
        if(hasUpper(word))
             result += 26;
        if(hasLower(word))
            result += 26;
        if(hasDigit(word))
            result +=10;

        result +=countSymbols(word,symbols);

        return result;
    }
}