package com.onaro.util.jfc.date;

import java.util.*;

/**
 * Time filter for "last-week" and "last-month". This is a relative time filter
 * that its start-time is relative to the time when it was requested.
 */
public class TimeFilterLast implements TimeFilter {

    /**
     * Start-time fields that are zeroed.
     */
    private static final int FIELDS_TO_CLEAN[] = new int[] {
        Calendar.MILLISECOND,
        Calendar.SECOND,
        Calendar.MINUTE,
        Calendar.HOUR_OF_DAY,
    };

    /**
     * The time field to role back when the start date is requested.
     */
    private int field;

    /**
     * Sets the time field that is subtructed from the current time to get the
     * start-time.
     * @param field <code>Calendar.WEEK_OF_MONTH</code> <code>field == Calendar.MONTH</code> only
     */
    public TimeFilterLast(int field) {
        assert field == Calendar.WEEK_OF_MONTH || field == Calendar.MONTH : "Wrong field value " + field; //$NON-NLS-1$
        this.field = field;
    }

    /**
     * Gets the start time by subtracting a whole unit of the selcted time-field
     * from the current time and zeroeing unimportant time fields.
     * @return the start-time
     */
    public Date getStartTime() {
        Calendar start = new GregorianCalendar();

        for (int i = 0; i < FIELDS_TO_CLEAN.length; ++i) {
            start.set(FIELDS_TO_CLEAN[i], 0);
        }

        switch (field) {
	    case Calendar.WEEK_OF_MONTH: /** Last week */
	        start.add(Calendar.WEEK_OF_MONTH, -1);
	        break;
	        
	    case Calendar.MONTH: /** Last month */
	        start.add(Calendar.MONTH, -1);
	        break;
            default:
                //do nothing
        }

        return start.getTime();
    }

    public Date getEndTime() {
        return new Date();
    }

    public String toString() {
        StringBuilder s = new StringBuilder("TimeFilterLast"); //$NON-NLS-1$
        s.append("[field=").append(field); //$NON-NLS-1$
        s.append(", startTime=").append(getStartTime()).append(']'); //$NON-NLS-1$
        return s.toString();
    }

    /**
     * Test if two filters are equal. Used to prevent unneeded server request if the
     * filter didn't really changed.
     * @param obj the other filter
     * @return true if the filters have thesame absolute start time
     */
    public boolean equals(Object obj) {
        if (obj == null || !(obj instanceof TimeFilterLast)) {
            return false;
        }

        TimeFilterLast other = (TimeFilterLast)obj;

        return field == other.field;
    }

    public int hashCode() {
        return field;
    }
}