Copyright (c) 2008, http://www.snakeyaml.org
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.
/**
 * Copyright (c) 2008, http://www.snakeyaml.org
 *
 * 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.representer;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.DumperOptions.FlowStyle;
import org.yaml.snakeyaml.DumperOptions.ScalarStyle;
import org.yaml.snakeyaml.introspector.PropertyUtils;
import org.yaml.snakeyaml.nodes.AnchorNode;
import org.yaml.snakeyaml.nodes.MappingNode;
import org.yaml.snakeyaml.nodes.Node;
import org.yaml.snakeyaml.nodes.NodeTuple;
import org.yaml.snakeyaml.nodes.ScalarNode;
import org.yaml.snakeyaml.nodes.SequenceNode;
import org.yaml.snakeyaml.nodes.Tag;

Represent basic YAML structures: scalar, sequence, mapping
/**
 * Represent basic YAML structures: scalar, sequence, mapping
 */
public abstract class BaseRepresenter {
    protected final Map<Class<?>, Represent> representers = new HashMap<Class<?>, Represent>();
    
in Java 'null' is not a type. So we have to keep the null representer
separately otherwise it will coincide with the default representer which
is stored with the key null.
/**
     * in Java 'null' is not a type. So we have to keep the null representer
     * separately otherwise it will coincide with the default representer which
     * is stored with the key null.
     */
    protected Represent nullRepresenter;
    // the order is important (map can be also a sequence of key-values)
    protected final Map<Class<?>, Represent> multiRepresenters = new LinkedHashMap<Class<?>, Represent>();
    protected DumperOptions.ScalarStyle defaultScalarStyle = null; //not explicitly defined
    protected FlowStyle defaultFlowStyle = FlowStyle.AUTO;
    protected final Map<Object, Node> representedObjects = new IdentityHashMap<Object, Node>() {
        private static final long serialVersionUID = -5576159264232131854L;

        public Node put(Object key, Node value) {
            return super.put(key, new AnchorNode(value));
        }
    };

    protected Object objectToRepresent;
    private PropertyUtils propertyUtils;
    private boolean explicitPropertyUtils = false;

    public Node represent(Object data) {
        Node node = representData(data);
        representedObjects.clear();
        objectToRepresent = null;
        return node;
    }

    protected final Node representData(Object data) {
        objectToRepresent = data;
        // check for identity
        if (representedObjects.containsKey(objectToRepresent)) {
            Node node = representedObjects.get(objectToRepresent);
            return node;
        }
        // }
        // check for null first
        if (data == null) {
            Node node = nullRepresenter.representData(null);
            return node;
        }
        // check the same class
        Node node;
        Class<?> clazz = data.getClass();
        if (representers.containsKey(clazz)) {
            Represent representer = representers.get(clazz);
            node = representer.representData(data);
        } else {
            // check the parents
            for (Class<?> repr : multiRepresenters.keySet()) {
                if (repr != null && repr.isInstance(data)) {
                    Represent representer = multiRepresenters.get(repr);
                    node = representer.representData(data);
                    return node;
                }
            }

            // check defaults
            if (multiRepresenters.containsKey(null)) {
                Represent representer = multiRepresenters.get(null);
                node = representer.representData(data);
            } else {
                Represent representer = representers.get(null);
                node = representer.representData(data);
            }
        }
        return node;
    }

    protected Node representScalar(Tag tag, String value, DumperOptions.ScalarStyle style) {
        if (style == null) {
            style = this.defaultScalarStyle;
        }
        Node node = new ScalarNode(tag, value, null, null, style);
        return node;
    }

    protected Node representScalar(Tag tag, String value) {
        return representScalar(tag, value, null);
    }

    protected Node representSequence(Tag tag, Iterable<?> sequence, DumperOptions.FlowStyle flowStyle) {
        int size = 10;// default for ArrayList
        if (sequence instanceof List<?>) {
            size = ((List<?>) sequence).size();
        }
        List<Node> value = new ArrayList<Node>(size);
        SequenceNode node = new SequenceNode(tag, value, flowStyle);
        representedObjects.put(objectToRepresent, node);
        DumperOptions.FlowStyle bestStyle = FlowStyle.FLOW;
        for (Object item : sequence) {
            Node nodeItem = representData(item);
            if (!(nodeItem instanceof ScalarNode && ((ScalarNode) nodeItem).isPlain())) {
                bestStyle = FlowStyle.BLOCK;
            }
            value.add(nodeItem);
        }
        if (flowStyle == FlowStyle.AUTO) {
            if (defaultFlowStyle != FlowStyle.AUTO) {
                node.setFlowStyle(defaultFlowStyle);
            } else {
                node.setFlowStyle(bestStyle);
            }
        }
        return node;
    }

    protected Node representMapping(Tag tag, Map<?, ?> mapping, DumperOptions.FlowStyle flowStyle) {
        List<NodeTuple> value = new ArrayList<NodeTuple>(mapping.size());
        MappingNode node = new MappingNode(tag, value, flowStyle);
        representedObjects.put(objectToRepresent, node);
        DumperOptions.FlowStyle bestStyle = FlowStyle.FLOW;
        for (Map.Entry<?, ?> entry : mapping.entrySet()) {
            Node nodeKey = representData(entry.getKey());
            Node nodeValue = representData(entry.getValue());
            if (!(nodeKey instanceof ScalarNode && ((ScalarNode) nodeKey).isPlain())) {
                bestStyle = FlowStyle.BLOCK;
            }
            if (!(nodeValue instanceof ScalarNode && ((ScalarNode) nodeValue).isPlain())) {
                bestStyle = FlowStyle.BLOCK;
            }
            value.add(new NodeTuple(nodeKey, nodeValue));
        }
        if (flowStyle == FlowStyle.AUTO) {
            if (defaultFlowStyle != FlowStyle.AUTO) {
                node.setFlowStyle(defaultFlowStyle);
            } else {
                node.setFlowStyle(bestStyle);
            }
        }
        return node;
    }

    public void setDefaultScalarStyle(ScalarStyle defaultStyle) {
        this.defaultScalarStyle = defaultStyle;
    }

    public ScalarStyle getDefaultScalarStyle() {
        if (defaultScalarStyle == null) {
            return ScalarStyle.PLAIN;
        }
        return defaultScalarStyle;
    }

    public void setDefaultFlowStyle(FlowStyle defaultFlowStyle) {
        this.defaultFlowStyle = defaultFlowStyle;
    }

    public FlowStyle getDefaultFlowStyle() {
        return this.defaultFlowStyle;
    }

    public void setPropertyUtils(PropertyUtils propertyUtils) {
        this.propertyUtils = propertyUtils;
        this.explicitPropertyUtils = true;
    }

    public final PropertyUtils getPropertyUtils() {
        if (propertyUtils == null) {
            propertyUtils = new PropertyUtils();
        }
        return propertyUtils;
    }

    public final boolean isExplicitPropertyUtils() {
        return explicitPropertyUtils;
    }
}