/*
 * [BritishEnglish.java]
 *
 * Summary: display a number in British Engish.
 *
 * 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 change definition of trillion and quadrillion
 *                 one hundred _and_ one.
 *  1.3 1999-01-16 trillion for 10ˆ18
 *  1.4 1999-01-21 make all language specific String literals into constants.
 */
package com.mindprod.inwords;

/**
 * display a number in British Engish.
 * <p/>
 * com.mindprod.inwords.BritishEnglish.java - convert long integer into
 * English words e.g.
 * -12345 -&gt; &quot;minus twelve thousand forty-five&quot;.
 * This is not the scheme used in the USA and Canada.
 * See com.mindprod.inwords.AmericanEnglish for the North American scheme
 * that
 * differs in the meaning
 * of billion, trillion etc.
 * <p/>
 * Special thanks go to Richard Hindle &lt;ritchie@sundog.demon.co.uk&gt;
 * for information on how British numbering works.
 * <p/>
 * Why is this code written in an unusual way?   see inwords.use
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.4 1999-01-21 make all language specific String literals into constants.
 * @since 1999-01-12
 */
public final class BritishEnglish implements ToWords
    {
    private static final int FIRST_COPYRIGHT_YEAR = 1999;

    private static final String AND = "and";

    /**
     * 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 = {
            /* lack of lead space is deliberate. */
            /*
            * We only need up to a quintillion, since a long is about 9 * 10 ^ 18
            */
            /* American: unit, hundred, thousand, million, trillion, quintillion */
            "",
            "hundred",
            "thousand",
            "million",
            "billion",
            "trillion" };

    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 = {
            /*
            * how many of this group is needed to form one of the succeeding group.
            */
            /* American: unit, hundred, thousand, million, trillion, quintillion */
            100,
            10,
            1000,
            1000000,
            1000000,
            1000000 };

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

    /**
     * convert long integer into British English words. -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 to words
     *
     * @return words
     * @noinspection WeakerAccess
     */
    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 ];
            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 );
                }
            boolean and = ( group == 0 ) && ( num != 0 );
            boolean comma =
                    ( group > 2 )
                    && ( s.length() != 0 )
                    && ( !s.startsWith( AND ) );
            s =
                    ( and ? AND + " " : "" )
                    + t
                    + " "
                    + groupName[ group ]
                    + ( comma ? ", " : " " )
                    + s;
            } // end for
        s = s.trim();
        if ( negative )
            {
            s = MINUS + " " + s;
            }
        return s;
        } // end inWords
    } // end BritishEnglish