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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.chararray.*;
import com.googlecode.concurrenttrees.radix.node.concrete.voidvalue.VoidValue;
import com.googlecode.concurrenttrees.radix.node.util.NodeUtil;

/**
 * A {@link NodeFactory} which creates various implementations of {@link Node} objects all of which store incoming
 * edge characters as a character array inside the node.
 * 
 * Returns an optimal node implementation depending on arguments supplied, which will be one of:
 * 

 *     {@link CharArrayNodeDefault} - contains all possible fields
 *     {@link CharArrayNodeNonLeafNullValue} - does not store a value, returns {@code null} for value
 *     {@link CharArrayNodeNonLeafVoidValue} - does not store a value, returns {@link VoidValue} for value
 *     {@link CharArrayNodeLeafVoidValue} - does not store child edges or a value, returns {@link VoidValue} for value
 *     {@link CharArrayNodeLeafWithValue} - does not store child edges, but does store a value
 * 
 * 
 * When the application supplies {@link VoidValue} for a value, this factory will omit actually storing that value
 * in the tree and will return one of the VoidValue-optimized nodes above which can reduce memory usage.
 *
 * @author Niall Gallagher
 */
public class DefaultCharArrayNodeFactory implements NodeFactory {

    private static final long serialVersionUID = 1L;

    @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;
        if (childNodes.isEmpty()) {
            // Leaf node...
            if (value instanceof VoidValue) {
                return new CharArrayNodeLeafVoidValue(edgeCharacters);
            }
            else if (value != null) {
                return new CharArrayNodeLeafWithValue(edgeCharacters, value);
            }
            else {
                return new CharArrayNodeLeafNullValue(edgeCharacters);
            }
        }
        else {
            // Non-leaf node...
            if (value instanceof VoidValue) {
                return new CharArrayNodeNonLeafVoidValue(edgeCharacters, childNodes);
            }
            else if (value == null) {
                return new CharArrayNodeNonLeafNullValue(edgeCharacters, childNodes);
            }
            else {
                return new CharArrayNodeDefault(edgeCharacters, value, childNodes);
            }
        }
    }

}