/*
 * Copyright 2012-2014 Red Hat, Inc.
 *
 * This file is part of Thermostat.
 *
 * Thermostat is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2, or (at your
 * option) any later version.
 *
 * Thermostat 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 Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Thermostat; see the file COPYING.  If not see
 * <http://www.gnu.org/licenses/>.
 *
 * Linking this code with other modules is making a combined work
 * based on this code.  Thus, the terms and conditions of the GNU
 * General Public License cover the whole combination.
 *
 * As a special exception, the copyright holders of this code give
 * you permission to link this code with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also
 * meet, for each linked independent module, the terms and conditions
 * of the license of that module.  An independent module is a module
 * which is not derived from or based on this code.  If you modify
 * this code, you may extend this exception to your version of the
 * library, but you are not obligated to do so.  If you do not wish
 * to do so, delete this exception statement from your version.
 */

package com.redhat.thermostat.storage.model;

import java.util.NoSuchElementException;
import java.util.Objects;

import com.redhat.thermostat.storage.core.Cursor;
import com.redhat.thermostat.storage.core.Entity;
import com.redhat.thermostat.storage.core.Persist;

/**
 * Model class for aggregate counts.
 *
 */
@Entity
public class AggregateCount implements AggregateResult {

    private long count;
    
    @Persist
    public long getCount() {
        return count;
    }
    
    @Persist
    public void setCount(long count) {
        this.count = count;
    }
    
    @Override
    public boolean equals(Object other) {
        if (!(other instanceof AggregateCount)) {
            return false;
        }
        AggregateCount o = (AggregateCount)other;
        return this.getCount() == o.getCount();
    }
    
    @Override
    public int hashCode() {
        return Objects.hash(getCount());
    }
    
    @SuppressWarnings("unchecked")
    public <T extends Pojo> Cursor<T> getCursor() {
        return (Cursor<T>) new AggregateCursor<>(this);
    }
    
    private static class AggregateCursor<T extends Pojo> implements Cursor<T> {

        private boolean available = true;
        private final T count;
        
        private AggregateCursor(T count) {
            this.count = count;
        }
        
        @Override
        public boolean hasNext() {
            return available; 
        }

        @Override
        public T next() {
            if (available) {
                available = false;
                return count;
            } else {
                throw new NoSuchElementException();
            }
        }
        
    }
}