public class repeatCon {

public void next() {
addMonth(1);
}

public void prev() {
addMonth(-1);
}

public repeatCon() {

Date d = system.today(); // default to today
Integer mo = d.month();
String m_param = System.currentPageReference().getParameters().get('mo');
String y_param = System.currentPageReference().getParameters().get('yr');

// allow a month to be passed in on the url as mo=10
if (m_param != null) {
Integer mi = Integer.valueOf(m_param);
if (mi > 0 && mi <= 12) {
d = Date.newInstance(d.year(),mi,d.day());
}
}
// and year as yr=2008
if (y_param != null) {
Integer yr = Integer.valueOf(y_param);
d = Date.newInstance(yr, d.month(), d.day());
}

setMonth(d);
}

public List<Month.Week> getWeeks() {
system.assert(month!=null,'month is null');
return month.getWeeks();
}

public Month getMonth() { return month; }


private void setMonth(Date d) {
month = new Month(d);
system.assert(month != null);

Date[] da = month.getValidDateRange(); // gather events that fall in this month
events = [ select id,subject,description,activitydate,activitydatetime,DurationInMinutes
from Event
where activitydate >= :da[0] AND activityDate <= :da[1]
order by activitydatetime];

month.setEvents(events); // merge those events into the month class
}

private void addMonth(Integer val) {
Date d = month.getFirstDate();
d = d.addMonths(val);
setMonth(d);
}

private List<Event> events;
private Month month;
}