package org.beanfabrics.samples.timespan;

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

import org.beanfabrics.model.AbstractPM;
import org.beanfabrics.model.ConversionException;
import org.beanfabrics.model.DatePM;
import org.beanfabrics.model.IntegerPM;
import org.beanfabrics.model.PMManager;
import org.beanfabrics.support.OnChange;
import org.beanfabrics.support.Validation;

/**
 * The TimeSpanPM is a presentation model for editing a period of time. The
 * start date must be before or equal the end date.
 */
public class TimeSpanPM extends AbstractPM {
    private static final long MS_PER_DAY = 1000 * 60 * 60 * 24;
    public final DatePM start = new DatePM();
    public final DatePM end = new DatePM();
    public final IntegerPM days = new IntegerPM();

    public TimeSpanPM() {
        PMManager.setup(this);
        start.setMandatory(true);
        end.setMandatory(true);
        days.setEditable(false);
    }

    public TimeSpanPM(Date startDate, Date endDate) {
        this();
        start.setDate(startDate);
        end.setDate(endDate);
    }

    /**
     * Validates start date and end date if their time span is a positive
     * period.
     * 
     * @return <code>true</code>, if the time span is a positive period
     */
    @Validation(path = { "start", "end" }, message = "This is not a valid time span")
    public boolean isPositivePeriod() {
        try {
            Date startDate = start.getDate();
            Date endDate = end.getDate();
            if (startDate == null || endDate == null) {
                // open periods are 'positive'
                return true;
            }
            return startDate.before(endDate) || startDate.equals(endDate);
        } catch (ConversionException ex) {
            // at least one of the date fields can't be converted to a Date object
            return false;
        }
    }

    /**
     * Calculates the number of days between start and end date, and updates the
     * "days" field with this value. This method is called automatically when
     * any of the date fields change.
     */
    @OnChange(path = { "start", "end" })
    public void updateDays() {
        if (!isValid()) {
            days.setText("");
        } else {
            GregorianCalendar startCal = new GregorianCalendar();
            startCal.setTime(start.getDate());
            GregorianCalendar endCal = new GregorianCalendar();
            endCal.setTime(end.getDate());
            days.setLong((endCal.getTimeInMillis() - startCal.getTimeInMillis()) / MS_PER_DAY);
        }
    }

    public Date getStartDate() {
        return start.getDate();
    }

    public void setStartDate(Date startDate) {
        this.start.setDate(startDate);
    }

    public Date getEndDate() {
        return end.getDate();
    }

    public void setEndDate(Date endDate) {
        this.end.setDate(endDate);
    }

}