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/*
 * Copyright 2012-2013 Niall Gallagher
 *
 * 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 com.googlecode.concurrenttrees.radix.node.concrete;

import com.googlecode.concurrenttrees.common.CharSequences;
import com.googlecode.concurrenttrees.radix.node.Node;
import com.googlecode.concurrenttrees.radix.node.NodeFactory;
import com.googlecode.concurrenttrees.radix.node.NodeList;
import com.googlecode.concurrenttrees.radix.node.concrete.bytearray.*;
import com.googlecode.concurrenttrees.radix.node.concrete.voidvalue.VoidValue;
import com.googlecode.concurrenttrees.radix.node.util.NodeUtil;

/**
 * A {@link NodeFactory} which creates {@link Node} objects which store incoming edge characters as a byte array inside
 * the node. This is similar to {@link DefaultCharArrayNodeFactory}, except nodes use a single byte to represent each
 * character in UTF-8, instead of Java's default 2-byte UFT-16 encoding.
 *  
 * This can reduce the memory overhead of storing character data by 50%, but supports only characters which can be
 * represented as a single byte in UTF-8. Throws an exception if characters are encountered which cannot be represented
 * as a single byte.
 *
 * @author Niall Gallagher
 */
public class DefaultByteArrayNodeFactory implements NodeFactory {

    private static final long serialVersionUID = 1L;

    private final boolean fast;

    public DefaultByteArrayNodeFactory() {
        fast = false;
    }

    DefaultByteArrayNodeFactory(boolean fast) {
        this.fast = fast;
    }

    @Override
    public Node createNode(CharSequence edgeCharacters, Object value, NodeList childNodes, boolean isRoot) {
        assert edgeCharacters != null : "The edgeCharacters argument was null";
        assert isRoot || edgeCharacters.length() > 0 : "Invalid edge characters for non-root node: " + CharSequences.toString(edgeCharacters);
        assert childNodes != null : "The edgeCharacters argument was null";
        assert NodeUtil.hasNoDuplicateEdges(childNodes) : "Duplicate edge detected in list of nodes supplied: " + childNodes;
        byte[] incomingEdgeCharArray = ByteArrayCharSequence.toSingleByteUtf8Encoding(edgeCharacters, fast);
        if (incomingEdgeCharArray == null) {
            return null;
        }
        if (childNodes.isEmpty()) {
            // Leaf node...
            if (value instanceof VoidValue) {
                return new ByteArrayNodeLeafVoidValue(incomingEdgeCharArray);
            }
            else if (value != null) {
                return new ByteArrayNodeLeafWithValue(incomingEdgeCharArray, value);
            }
            else {
                return new ByteArrayNodeLeafNullValue(incomingEdgeCharArray);
            }
        }
        else {
            // Non-leaf node...
            if (value instanceof VoidValue) {
                return new ByteArrayNodeNonLeafVoidValue(incomingEdgeCharArray, childNodes);
            }
            else if (value == null) {
                return new ByteArrayNodeNonLeafNullValue(incomingEdgeCharArray, childNodes);
            }
            else {
                return new ByteArrayNodeDefault(incomingEdgeCharArray, value, childNodes);
            }
        }
    }

}