/**
 * A fairly silly example of a class that implements the Comparable interface. 
 * In this case, comparability from right to left.
 * @author gtowell
 * Created: March 2021
 * Modified: Aug 6, 2021
 */
public class CompEx implements Comparable<CompEx> {
    // The only variable
    private String theString;

    /**
     * Constructor
     * @param strng sets the internal var
     */
    public CompEx(String strng) {
        theString = strng;
    }

    // getter
    public String getString() {
        return theString;
    }

    // toString
    public String toString() {
        return theString;
    }

    /**
     * Implements the comparable interface
     * Will do a case insensityve comparison of the values of the strings in each instance
     */
    public int compareTo(CompEx o) {
        if (theString == null)
            return -1;
        if (o.getString() == null)
            return 1;
        // downcase both strings.
        String s1 = theString;
        String s2 = o.getString();
        int l = s1.length();
        if (s2.length() < l)
            l = s2.length();
        // do a letter by letter comparison right to left -- stopping at first letter that is not the same.
        for (int i = (l-1); i >= 0; i--) {
            int d = s1.charAt(i) - s2.charAt(i); // subtract ASCII value
            if (d != 0)
                return d;
        }
        // strings are identical to length of shorter string.
        // Now just handle different length problem
        if (s1.length() == s2.length())
            return 0;
        if (s1.length() > s2.length())
            return 1;
        return -1;
    }    


    public static void main(String[] args) {
        String[] a = { "a", "ab", "abc", "bac"};
        String[] b = { "a", "ab", "bac", "dbc"};
        for (int i = 0; i < a.length; i++) {
            CompEx is1 = new CompEx(a[i]);
            CompEx is2 = new CompEx(b[i]);
            System.out.println(is1 + " " + is2 + " " + is1.compareTo(is2));
            System.out.println("StringComp: " + is1 + " " + is2 + " " + is1.getString().compareTo(is2.getString()));

        }
        // this line does not work because compareTo only defined for same class
        // System.out.println(new CompEx("AA").compareTo("BB"));
    }

}