/**
 * Copyright (c) 2008-2009 Andrey Somov
 *
 * 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.yaml.snakeyaml.nodes;

import org.yaml.snakeyaml.error.Mark;

/**
 * @see <a href="http://pyyaml.org/wiki/PyYAML">PyYAML</a> for more information
 */
public abstract class Node {
    private String tag;
    private Mark startMark;
    protected Mark endMark;
    private Class<? extends Object> type;
    private boolean twoStepsConstruction;
    /**
     * true when the tag is assigned by the resolver
     */
    protected boolean resolved;
    protected Boolean useClassConstructor;

    public Node(String tag, Mark startMark, Mark endMark) {
        setTag(tag);
        this.startMark = startMark;
        this.endMark = endMark;
        this.type = Object.class;
        this.twoStepsConstruction = false;
        this.resolved = true;
        this.useClassConstructor = null;
    }

    public String getTag() {
        return this.tag;
    }

    public Mark getEndMark() {
        return endMark;
    }

    /**
     * For error reporting.
     * 
     * @see class variable 'id' in PyYAML
     * @return scalar, sequence, mapping
     */
    public abstract NodeId getNodeId();

    public Mark getStartMark() {
        return startMark;
    }

    public void setTag(String tag) {
        if (tag == null) {
            throw new NullPointerException("tag in a Node is required.");
        }
        this.tag = tag;
    }

    /*
     * It is not allowed to overwrite this method. Two Nodes are never equal.
     */
    @Override
    public final boolean equals(Object obj) {
        return super.equals(obj);
    }

    public Class<? extends Object> getType() {
        return type;
    }

    public void setType(Class<? extends Object> type) {
        this.type = type;
    }

    public void setTwoStepsConstruction(boolean twoStepsConstruction) {
        this.twoStepsConstruction = twoStepsConstruction;
    }

    public boolean isTwoStepsConstruction() {
        return twoStepsConstruction;
    }

    @Override
    public final int hashCode() {
        return super.hashCode();
    }

    public boolean useClassConstructor() {
        if (useClassConstructor == null) {
            if (resolved && !Object.class.equals(type) && !tag.equals(Tags.NULL)) {
                return true;
            } else {
                return false;
            }
        }
        return useClassConstructor.booleanValue();
    }

    // TODO do we need it ?
    public void setUseClassConstructor(Boolean useClassConstructor) {
        this.useClassConstructor = useClassConstructor;
    }

    public boolean isResolved() {
        return resolved;
    }
}