/*
 * [InaugurationDay.java]
 *
 * Summary: calculate when US presidential Inauguration day occurs.
 *
 * 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:
 *  4.2 2008-12-03 add World AIDS day
 */
package com.mindprod.holidays;

import com.mindprod.common18.BigDate;

/**
 * calculate when US presidential Inauguration day occurs.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 4.2 2008-12-03 add World AIDS day
 * @since 1999
 */
public final class InaugurationDay extends HolInfo
    {
    /**
     * @inheritDoc
     */
    public String getAuthority()
        {
        // http://edsitement.neh.fed.us/lessonplans/inaugurations.html
        // http://edsitement.neh.fed.us/lessonplans/inaugurations.html
        return "http://www.geocities.com/holidaymobley/InaugurationDay.html";
        }

    /**
     * @inheritDoc
     */
    public int getFirstYear( int base )
        {
        return 1789;
        }

    /**
     * @inheritDoc
     */
    public String getName()
        {
        return "US Presidential Inauguration Day";
        }

    /**
     * @inheritDoc
     */
    public String getRule()
        {
        return "noon, January 20, every four years, but never on a Sunday.";
        // Ford : 1974-08-09, (unscheduled)
        // Carter: 1977-10-20 Tuesday
        // Reagan: 1981-01-20 Tuesday
        // Bush Sr. 1989-01-20Friday
        // Clinton: 19930-01-20 Wednesday
        // Bush Jr: 2001-01-20 Saturday
        // Bush second: 2005-01-20 Thursday
        }

    /**
     * @inheritDoc
     */
    public int when( int year, boolean shift, int base )
        {
        if ( !isYearValid( year, base ) )
            {
            return BigDate.NULL_ORDINAL;
            }
        if ( year % 4 != 1 )
            {
            return BigDate.NULL_ORDINAL;
            }
        int ordinal;
        if ( year == 1789 )
            {
            ordinal = BigDate.toOrdinal( year, 4, 30 );
            }
        else if ( year < 1937 )
            {
            /* March 4 */
            ordinal = BigDate.toOrdinal( year, 3, 4 );
            }
        else
            {
            /* January 20 */
            ordinal = BigDate.toOrdinal( year, 1, 20 );
            }
        if ( BigDate.dayOfWeek( ordinal ) == 0 )
            {
            /* sunday shift to Monday */
            ordinal++;
            }
        return shiftSatToFriSunToMon( ordinal, shift );
        } // end when.
    }