/*
 * #%L
 * Netarchivesuite - harvester
 * %%
 * Copyright (C) 2005 - 2014 The Royal Danish Library, the Danish State and University Library,
 *             the National Library of France and the Austrian National Library.
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/lgpl-2.1.html>.
 * #L%
 */

package dk.netarkivet.harvester.datamodel;

import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

import dk.netarkivet.common.exceptions.ArgumentNotValid;

/**
 * This class implements a frequency of a number of hours.
 */
public class HourlyFrequency extends Frequency {

    /** The minute of the hour the event should happen at. */
    private int minute;

    /**
     * Create a new HourlyFrequency that happens every numUnits hours, at an unspecified minute.
     *
     * @param numUnits Number of hours from one event to the next
     * @throws ArgumentNotValid if numUnits if 0 or negative
     */
    public HourlyFrequency(int numUnits) {
        super(numUnits, true);
    }

    /**
     * Create a new HourlyFrequency that happens every numUnits hours, on the minute.
     *
     * @param numUnits Number of hours from one event to the next
     * @param minute What minute of the hour the event should happen on.
     * @throws ArgumentNotValid if numUnits if 0 or negative or minutes is <0 or >59
     */
    public HourlyFrequency(int numUnits, int minute) {
        super(numUnits, false);
        Calendar cal = GregorianCalendar.getInstance();
        if (minute < cal.getMinimum(Calendar.MINUTE) || minute > cal.getMaximum(Calendar.MINUTE)) {
            throw new ArgumentNotValid("Minute must be in legal range '" + cal.getMinimum(Calendar.MINUTE) + "' to '"
                    + cal.getMaximum(Calendar.MINUTE) + "'");
        }

        this.minute = minute;
    }

    /**
     * Given when the last event happened, tell us when the next event should happen (even if the new event is in the
     * past).
     * <p>
     * The time of the next event is guaranteed to be later that lastEvent. For certain frequencies (e.g. once a day,
     * any time of day), the time of the next event is derived from lastEvent, for others (e.g. once a day at 13:00) the
     * time of the next event is the first matching time after lastEvent.
     *
     * @param lastEvent A time from which the next event should be calculated.
     * @return At what point the event should happen next.
     * @throws ArgumentNotValid if lastEvent is null
     */
    public Date getNextEvent(Date lastEvent) {
        ArgumentNotValid.checkNotNull(lastEvent, "lastEvent");

        Calendar last = new GregorianCalendar();
        last.setTime(getFirstEvent(lastEvent));
        last.add(Calendar.HOUR_OF_DAY, getNumUnits());
        return getFirstEvent(last.getTime());
    }

    /**
     * Given a starting time, tell us when the first event should happen.
     *
     * @param startTime The earliest time the event can happen.
     * @return At what point the event should happen the first time.
     * @throws ArgumentNotValid if startTime is null
     */
    public Date getFirstEvent(Date startTime) {
        ArgumentNotValid.checkNotNull(startTime, "startTime");

        if (isAnytime()) {
            return startTime;
        }
        Calendar start = new GregorianCalendar();
        start.setTime(startTime);
        start.set(Calendar.MINUTE, minute);
        if (start.getTime().before(startTime)) {
            start.add(Calendar.HOUR_OF_DAY, 1);
        }
        return start.getTime();

    }

    /**
     * If not anytime, the minute at which events should start.
     *
     * @return the minute
     */
    public int getMinute() {
        return minute;
    }

    /**
     * Autogenerated equals.
     *
     * @param o The object to compare with
     * @return Whether objects are equal
     */
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof HourlyFrequency)) {
            return false;
        }
        if (!super.equals(o)) {
            return false;
        }

        final HourlyFrequency hourlyFrequency = (HourlyFrequency) o;

        if (isAnytime()) {
            return true;
        }

        if (minute != hourlyFrequency.minute) {
            return false;
        }

        return true;
    }

    /**
     * Autogenerated hashcode method.
     *
     * @return the hashcode
     */
    public int hashCode() {
        int result = super.hashCode();
        result = 29 * result + minute;
        return result;
    }

    /**
     * Return the exact minute event should happen on, or null if this is an anyTime event or doesn't define what minute
     * it should happen on.
     *
     * @return the exact minute event should happen on
     */
    public Integer getOnMinute() {
        if (!isAnytime()) {
            return minute;
        }
        return null;
    }

    /**
     * Return the exact hour event should happen on, or null if this is an anyTime event or doesn't define what hour it
     * should happen on.
     *
     * @return null always
     */
    public Integer getOnHour() {
        return null;
    }

    /**
     * Return the exact day of week event should happen on, or null if this is an anyTime event or doesn't define what
     * day of week it should happen on.
     *
     * @return null always
     */
    public Integer getOnDayOfWeek() {
        return null;
    }

    /**
     * Return the exact day of month event should happen on, or null if this is an anyTime event or doesn't define what
     * day of month it should happen on.
     *
     * @return null (always)
     */
    public Integer getOnDayOfMonth() {
        return null;
    }

    /**
     * Return an integer that can be used to identify the kind of frequency. No two subclasses should use the same
     * integer
     *
     * @return an integer that can be used to identify the kind of frequency
     */
    public int ordinal() {
        return TimeUnit.HOURLY.ordinal();
    }

    /**
     * Human readable representation of this object.
     *
     * @return Human readable representation
     */
    public String toString() {
        if (isAnytime()) {
            return "every " + getNumUnits() + " hours";
        }
        return "every " + getNumUnits() + " hours at " + minute;
    }

}