/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.storm.starter.tools;

import java.io.Serializable;
import java.util.List;

import backtype.storm.tuple.Tuple;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

/**
 * This class wraps an objects and its associated count, including any
 * additional data fields.
 * <p/>
 * This class can be used, for instance, to track the number of occurrences of
 * an object in a Storm topology.
 */
public class RankableObjectWithFields implements Rankable, Serializable {
    
    private static final long   serialVersionUID  = -9102878650001058090L;
    private static final String toStringSeparator = "|";
    
    private final Object                obj;
    private final long                  count;
    private final ImmutableList<Object> fields;
    
    public RankableObjectWithFields(Object obj, long count, Object... otherFields) {
        if (obj == null) {
            throw new IllegalArgumentException("The object must not be null");
        }
        if (count < 0) {
            throw new IllegalArgumentException("The count must be >= 0");
        }
        this.obj = obj;
        this.count = count;
        fields = ImmutableList.copyOf(otherFields);
        
    }
    
    /**
     * Construct a new instance based on the provided {@link Tuple}.
     * <p/>
     * This method expects the object to be ranked in the first field (index 0)
     * of the provided tuple, and the number of occurrences of the object (its
     * count) in the second field (index 1). Any further fields in the tuple
     * will be extracted and tracked, too. These fields can be accessed via
     * {@link RankableObjectWithFields#getFields()}.
     *
     * @param tuple
     *           
     * @return new instance based on the provided tuple
     */
    public static RankableObjectWithFields from(Tuple tuple) {
        List<Object> otherFields = Lists.newArrayList(tuple.getValues());
        Object obj = otherFields.remove(0);
        Long count = (Long) otherFields.remove(0);
        return new RankableObjectWithFields(obj, count, otherFields.toArray());
    }
    
    public Object getObject() {
        return obj;
    }
    
    public long getCount() {
        return count;
    }
    
    /**
     * @return an immutable list of any additional data fields of the object
     *         (may be empty but will never be null)
     */
    public List<Object> getFields() {
        return fields;
    }
    
    @Override
    public int compareTo(Rankable other) {
        long delta = this.getCount() - other.getCount();
        if (delta > 0) {
            return 1;
        } else if (delta < 0) {
            return -1;
        } else {
            return 0;
        }
    }
    
    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (!(o instanceof RankableObjectWithFields)) {
            return false;
        }
        RankableObjectWithFields other = (RankableObjectWithFields) o;
        return obj.equals(other.obj) && count == other.count;
    }
    
    @Override
    public int hashCode() {
        int result = 17;
        int countHash = (int) (count ^ (count >>> 32));
        result = 31 * result + countHash;
        result = 31 * result + obj.hashCode();
        return result;
    }
    
    public String toString() {
        StringBuffer buf = new StringBuffer();
        buf.append("[");
        buf.append(obj);
        buf.append(toStringSeparator);
        buf.append(count);
        for (Object field : fields) {
            buf.append(toStringSeparator);
            buf.append(field);
        }
        buf.append("]");
        return buf.toString();
    }
    
    /**
     * Note: We do not defensively copy the wrapped object and any accompanying
     * fields. We do guarantee, however, do return a defensive (shallow) copy of
     * the List object that is wrapping any accompanying fields.
     *
     * @return
     */
    @Override
    public Rankable copy() {
        List<Object> shallowCopyOfFields = ImmutableList.copyOf(getFields());
        return new RankableObjectWithFields(getObject(), getCount(), shallowCopyOfFields);
    }
    
}