/*
 * Copyright 2012 Takao Nakaguchi
 *
 * Licensed 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.trie4j.tail.index;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Arrays;

public class ArrayTailIndexBuilder
implements Externalizable, TailIndexBuilder{
	public ArrayTailIndexBuilder() {
	}

	public ArrayTailIndexBuilder(int initialCapacity) {
		tail = new int[initialCapacity];
		Arrays.fill(tail, -1);
	}

	@Override
	public void add(int nodeId, int start, int end) {
		ensureCapacity(nodeId);
		tail[nodeId] = start;
	}
	
	@Override
	public void addEmpty(int nodeId) {
		ensureCapacity(nodeId);
		tail[nodeId] = -1;
	}

	@Override
	public TailIndex build() {
		trimToSize();
		return new ArrayTailIndex(tail);
	}

	@Override
	public void trimToSize() {
		tail = Arrays.copyOf(tail, size);
	}

	private void ensureCapacity(int nodeId){
		if(nodeId < size){
			return;
		}
		if(nodeId >= tail.length){
			tail = Arrays.copyOf(tail, (int)((nodeId + 1) * 1.2));
			Arrays.fill(tail, size, tail.length, -1);
		}
		size = nodeId + 1;
	}

	@Override
	public void readExternal(ObjectInput in)
	throws ClassNotFoundException, IOException{
		size = in.readInt();
		tail = (int[])in.readObject();
	}

	@Override
	public void writeExternal(ObjectOutput out) throws IOException {
		trimToSize();
		out.writeInt(size);
		out.writeObject(tail);
	}

	private int[] tail = new int[]{};
	private int size;
}