/*
 * [AmericanEnglish.java]
 *
 * Summary: display a number in American English words.
 *
 * Copyright: (c) 1999-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.0 1999-01-12
 *  1.1 1999-01-13 more table driven
 *                 handles longs, not just int.
 *  1.2 1999-01-14 1900 -> "ninteen hundred"
 *  1.3 1999-01-16 fix 21199 twenty-one thousand one hundred ninety-nine was coming out twenty thousand eleven
 *                 hundred ninety-nine.
 *  1.4 1999-01-16 5900 is now fify-nine hundred, 6900 is six thousand nine hundred.
 *  1.5 1999-01-20 correct so that 9900 is done as nine thousand nine hundred.
 *  1.6 1999-01-21 make all language specific String literals into constants.
 */
package com.mindprod.inwords;

/**
 * display a number in American English words.
 * <p/>
 * e.g.
 * -12345 -&gt; &quot;minus twelve thousand forty-five&quot;
 * This is the scheme used in the USA and Canada.
 * See com.mindprod.inwords.BritishEnglish for the British scheme
 * that differs in the meaning
 * of billion.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.6 1999-01-21 make all language specific String literals into constants.
 * Why is this code written the way it is? see inwords.use
 * @since 1999-01-12
 */
public class AmericanEnglish implements ToWords
    {
    private static final int FIRST_COPYRIGHT_YEAR = 1999;

    /**
     * undisplayed copyright notice
     *
     * @noinspection UnusedDeclaration
     */
    private static final String EMBEDDED_COPYRIGHT =
            "Copyright: (c) 1999-2017 Roedy Green, Canadian Mind Products, http://mindprod.com";

    private static final String MINUS = "minus";

    private static final String ZERO = "zero";

    private static final String[] groupName = {
            /*
            * We only need up to a quintillion, since a long is about 9 * 10 ^ 18
            */
            /*
            * American: unit, hundred, thousand, million, billion, trillion,
            * quadrillion, quintillion
            */
            "",
            "hundred",
            "thousand",
            "million",
            "billion",
            "trillion",
            "quadrillion",
            "quintillion" };

    private static final String[] lowName = {
            /* zero is shown as "" since it is never used in combined forms */
            /* 0 .. 19 */
            "",
            "one",
            "two",
            "three",
            "four",
            "five",
            "six",
            "seven",
            "eight",
            "nine",
            "ten",
            "eleven",
            "twelve",
            "thirteen",
            "fourteen",
            "fifteen",
            "sixteen",
            "seventeen",
            "eighteen",
            "nineteen" };

    private static final String[] tys = {
            /* 0, 10, 20, 30 ... 90 */
            "",
            "",
            "twenty",
            "thirty",
            "forty",
            "fifty",
            "sixty",
            "seventy",
            "eighty",
            "ninety" };

    private static final int[] divisor = {
            /*
            * HowToProcess many of this group is needed to form one of the succeeding group.
            */
            /*
            * American: unit, hundred, thousand, million, billion, trillion,
            * quadrillion, quintillion
            */
            100, 10, 1000, 1000, 1000, 1000, 1000, 1000 };

    /**
     * test harness
     *
     * @param args not used
     */
    public static void main( String[] args )
        {
        Test.test( new AmericanEnglish() );
        } // end main

    /**
     * convert long integer into American English words. e.g. -12345 -> "minus twelve thousand forty-five" Handles
     * negative and positive integers on range -Long.MAX_VALUE .. Long.MAX_VALUE; It cannot handle Long.MIN_VALUE;
     *
     * @param num number to convert into words
     *
     * @return number in words.
     */
    public String toWords( long num )
        {
        if ( num == 0 )
            {
            return ZERO;
            }
        boolean negative = ( num < 0 );
        if ( negative )
            {
            num = -num;
            }
        String s = "";
        // Work least significant digit to most, right to left.
        // until high order part is all 0s.
        for ( int group = 0; num > 0; group++ )
            {
            int remdr = ( int ) ( num % divisor[ group ] );
            num = num / divisor[ group ];
            // check for 1100 .. 1999, 2100..2999, ... 5200..5999
            // but not 1000..1099, 2000..2099, ...
            // Special case written as fifty-nine hundred.
            // e.g. thousands digit is 1..5 and hundreds digit is 1..9
            // Only when no further higher order.
            if ( group == 1/* doing hundreds */ && 1 <= num && num <= 5 )
                {
                if ( remdr > 0 )
                    {
                    remdr += num * 10;
                    num = 0;
                    } // end if
                } // end if
            if ( remdr == 0 )
                {
                continue;
                }
            String t;
            if ( remdr < 20 )
                {
                t = lowName[ remdr ];
                }
            else if ( remdr < 100 )
                {
                int units = remdr % 10;
                int tens = remdr / 10;
                t = tys[ tens ];
                if ( units != 0 )
                    {
                    t += "-" + lowName[ units ];
                    }
                }
            else
                {
                t = toWords( remdr );
                }
            s = t + " " + groupName[ group ] + " " + s;
            } // end for
        s = s.trim();
        if ( negative )
            {
            s = MINUS + " " + s;
            }
        return s;
        } // end inWords
    } // end AmericanEnglish