package com.github.lucasb.opencode.idbase62;

/**
 * 
 * This class provide base 62 elements.
 * 
 * @author Boscaini, Lucas
 * 
 */
public class Base62 {

    public static final char[] ELEMENTS = {    'a', 'b', 'c', 'd', 'e', 'f', 
            'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 
            't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', 
            '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 
            'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 
            'W', 'X', 'Y', 'Z' };
    
    public static final long BASE = ELEMENTS.length;

    /**
     * 
     * Convert a value from decimal to base 62.
     * 
     * @param decimal
     *            Long with decimal value to convert.
     * @return a string with base 62 value.
     * 
     */
    public static String fromDecimal(long decimal) {
        StringBuilder sb = new StringBuilder("");

        if (decimal == 0) {
            return String.valueOf(ELEMENTS[0]);
        }

        while (decimal > 0) {
            long rest = decimal % BASE;
            sb.append(ELEMENTS[(int) rest]);
            decimal = decimal / BASE;
        }

        return sb.reverse().toString();
    }

    /**
     * 
     * Convert a value from base 62 to decimal.
     * 
     * @param value
     *            String with base 62 value to convert.
     * @return a long with decimal value.
     * 
     */
    public static long toDecimal(String value) {
        char[] chars = new StringBuilder(value).reverse().toString().toCharArray();
        long n = 0;

        for (int i = chars.length - 1; i >= 0; i--) {
            n += (new String(ELEMENTS).indexOf(chars[i])) * (long) Math.pow(BASE, i);
        }

        return n;
    }

    /**
     * 
     * Plus two base 62 values.
     * 
     * @param value
     *            String with base 62 value.
     * @param value2
     *            String with base 62 value.
     * @return a string with result base 62 value.
     * 
     */
    public static String plus(String value, String value2) {
        return fromDecimal(toDecimal(value) + toDecimal(value2));
    }

    /**
     * 
     * Subtract two base 62 values, first value to second.
     * 
     * @param value
     *            String with base 62 value.
     * @param value2
     *            String with base 62 value.
     * @return a long with decimal value.
     * 
     */
    public static String minus(String value, String value2) {
        return fromDecimal(toDecimal(value) - toDecimal(value2));
    }

    /**
     * 
     * Valid if the value is base 62 type or not.
     * 
     * @param value
     *            String with base 62 value.
     * @return a boolean with true if and only if the value is valid.
     * 
     */
    public static boolean isValid(String value) {

        if (value == null || value.trim().equals("")) {
            return false;
        }

        for (int i = 0; i < value.length(); i++) {
            if (new String(ELEMENTS).indexOf(value.charAt(i)) == -1) {
                return false;
            }
        }
        return true;
    }

}

@@ -725,34 +725,16 @@
  decimal
-%0A     *           
  Long wi

Fix comment.