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.constructor;

import org.yaml.snakeyaml.LoaderOptions;
import org.yaml.snakeyaml.TypeDescription;
import org.yaml.snakeyaml.composer.Composer;
import org.yaml.snakeyaml.composer.ComposerException;
import org.yaml.snakeyaml.error.YAMLException;
import org.yaml.snakeyaml.introspector.PropertyUtils;
import org.yaml.snakeyaml.nodes.CollectionNode;
import org.yaml.snakeyaml.nodes.MappingNode;
import org.yaml.snakeyaml.nodes.Node;
import org.yaml.snakeyaml.nodes.NodeId;
import org.yaml.snakeyaml.nodes.NodeTuple;
import org.yaml.snakeyaml.nodes.ScalarNode;
import org.yaml.snakeyaml.nodes.SequenceNode;
import org.yaml.snakeyaml.nodes.Tag;

import java.lang.reflect.Array;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;

public abstract class BaseConstructor {
    
It maps the node kind to the the Construct implementation. When the
runtime class is known then the implicit tag is ignored.
/**
     * It maps the node kind to the the Construct implementation. When the
     * runtime class is known then the implicit tag is ignored.
     */
    protected final Map<NodeId, Construct> yamlClassConstructors = new EnumMap<NodeId, Construct>(
            NodeId.class);
    
It maps the (explicit or implicit) tag to the Construct implementation.
It is used:
1) explicit tag - if present.
2) implicit tag - when the runtime class of the instance is unknown (the
node has the Object.class)
/**
     * It maps the (explicit or implicit) tag to the Construct implementation.
     * It is used:
     * 1) explicit tag - if present.
     * 2) implicit tag - when the runtime class of the instance is unknown (the
     * node has the Object.class)
     */
    protected final Map<Tag, Construct> yamlConstructors = new HashMap<Tag, Construct>();
    
It maps the (explicit or implicit) tag to the Construct implementation.
It is used when no exact match found.
/**
     * It maps the (explicit or implicit) tag to the Construct implementation.
     * It is used when no exact match found.
     */
    protected final Map<String, Construct> yamlMultiConstructors = new HashMap<String, Construct>();

    protected Composer composer;
    final Map<Node, Object> constructedObjects;
    private final Set<Node> recursiveObjects;
    private final ArrayList<RecursiveTuple<Map<Object, Object>, RecursiveTuple<Object, Object>>> maps2fill;
    private final ArrayList<RecursiveTuple<Set<Object>, Object>> sets2fill;

    protected Tag rootTag;
    private PropertyUtils propertyUtils;
    private boolean explicitPropertyUtils;
    private boolean allowDuplicateKeys = true;

    private boolean wrappedToRootException = false;

    protected final Map<Class<? extends Object>, TypeDescription> typeDefinitions;
    protected final Map<Tag, Class<? extends Object>> typeTags;

    protected LoaderOptions loadingConfig;

    public BaseConstructor() {
        this(new LoaderOptions());
    }

    public BaseConstructor(LoaderOptions loadingConfig) {
        constructedObjects = new HashMap<Node, Object>();
        recursiveObjects = new HashSet<Node>();
        maps2fill = new ArrayList<RecursiveTuple<Map<Object, Object>, RecursiveTuple<Object, Object>>>();
        sets2fill = new ArrayList<RecursiveTuple<Set<Object>, Object>>();
        typeDefinitions = new HashMap<Class<? extends Object>, TypeDescription>();
        typeTags = new HashMap<Tag, Class<? extends Object>>();

        rootTag = null;
        explicitPropertyUtils = false;

        typeDefinitions.put(SortedMap.class, new TypeDescription(SortedMap.class, Tag.OMAP,
                TreeMap.class));
        typeDefinitions.put(SortedSet.class, new TypeDescription(SortedSet.class, Tag.SET,
                TreeSet.class));
        this.loadingConfig = loadingConfig;
    }

    public void setComposer(Composer composer) {
        this.composer = composer;
    }

    
Check if more documents available
Returns:
true when there are more YAML documents in the stream/**
     * Check if more documents available
     *
     * @return true when there are more YAML documents in the stream
     */
    public boolean checkData() {
        // If there are more documents available?
        return composer.checkNode();
    }

    
Construct and return the next document
Returns:
constructed instance/**
     * Construct and return the next document
     *
     * @return constructed instance
     */
    public Object getData() throws NoSuchElementException {
        // Construct and return the next document.
        if (!composer.checkNode()) throw new NoSuchElementException("No document is available.");
        Node node = composer.getNode();
        if (rootTag != null) {
            node.setTag(rootTag);
        }
        return constructDocument(node);
    }

    
Ensure that the stream contains a single document and construct it
Params:
type – the class of the instance being created
Throws:
ComposerException – in case there are more documents in the stream
Returns:
constructed instance/**
     * Ensure that the stream contains a single document and construct it
     *
     * @param type the class of the instance being created
     * @return constructed instance
     * @throws ComposerException in case there are more documents in the stream
     */
    public Object getSingleData(Class<?> type) {
        // Ensure that the stream contains a single document and construct it
        final Node node = composer.getSingleNode();
        if (node != null && !Tag.NULL.equals(node.getTag())) {
            if (Object.class != type) {
                node.setTag(new Tag(type));
            } else if (rootTag != null) {
                node.setTag(rootTag);
            }
            return constructDocument(node);
        } else {
            Construct construct = yamlConstructors.get(Tag.NULL);
            return construct.construct(node);
        }
    }

    
Construct complete YAML document. Call the second step in case of
recursive structures. At the end cleans all the state.
Params:
node – root Node
Returns:
Java instance/**
     * Construct complete YAML document. Call the second step in case of
     * recursive structures. At the end cleans all the state.
     *
     * @param node root Node
     * @return Java instance
     */
    protected final Object constructDocument(Node node) {
        try {
            Object data = constructObject(node);
            fillRecursive();
            return data;
        } catch (RuntimeException e) {
            if (wrappedToRootException && !(e instanceof YAMLException)) {
                throw new YAMLException(e);
            } else {
                throw e;
            }
        } finally {
            //clean up resources
            constructedObjects.clear();
            recursiveObjects.clear();
        }
    }

    
Fill the recursive structures and clean the internal collections
/**
     * Fill the recursive structures and clean the internal collections
     */
    private void fillRecursive() {
        if (!maps2fill.isEmpty()) {
            for (RecursiveTuple<Map<Object, Object>, RecursiveTuple<Object, Object>> entry : maps2fill) {
                RecursiveTuple<Object, Object> key_value = entry._2();
                entry._1().put(key_value._1(), key_value._2());
            }
            maps2fill.clear();
        }
        if (!sets2fill.isEmpty()) {
            for (RecursiveTuple<Set<Object>, Object> value : sets2fill) {
                value._1().add(value._2());
            }
            sets2fill.clear();
        }
    }

    
Construct object from the specified Node. Return existing instance if the
node is already constructed.
Params:
node – Node to be constructed
Returns:
Java instance/**
     * Construct object from the specified Node. Return existing instance if the
     * node is already constructed.
     *
     * @param node Node to be constructed
     * @return Java instance
     */
    protected Object constructObject(Node node) {
        if (constructedObjects.containsKey(node)) {
            return constructedObjects.get(node);
        }
        return constructObjectNoCheck(node);
    }

    protected Object constructObjectNoCheck(Node node) {
        if (recursiveObjects.contains(node)) {
            throw new ConstructorException(null, null, "found unconstructable recursive node",
                    node.getStartMark());
        }
        recursiveObjects.add(node);
        Construct constructor = getConstructor(node);
        Object data = (constructedObjects.containsKey(node)) ? constructedObjects.get(node)
                : constructor.construct(node);

        finalizeConstruction(node, data);
        constructedObjects.put(node, data);
        recursiveObjects.remove(node);
        if (node.isTwoStepsConstruction()) {
            constructor.construct2ndStep(node, data);
        }
        return data;
    }

    
Get the constructor to construct the Node. For implicit tags if the
runtime class is known a dedicated Construct implementation is used.
Otherwise the constructor is chosen by the tag.
Params:
node – Node to construct an instance from
Returns:
Construct implementation for the specified node/**
     * Get the constructor to construct the Node. For implicit tags if the
     * runtime class is known a dedicated Construct implementation is used.
     * Otherwise the constructor is chosen by the tag.
     *
     * @param node {@link Node} to construct an instance from
     * @return {@link Construct} implementation for the specified node
     */
    protected Construct getConstructor(Node node) {
        if (node.useClassConstructor()) {
            return yamlClassConstructors.get(node.getNodeId());
        } else {
            Construct constructor = yamlConstructors.get(node.getTag());
            if (constructor == null) {
                for (String prefix : yamlMultiConstructors.keySet()) {
                    if (node.getTag().startsWith(prefix)) {
                        return yamlMultiConstructors.get(prefix);
                    }
                }
                return yamlConstructors.get(null);
            }
            return constructor;
        }
    }

    protected String constructScalar(ScalarNode node) {
        return node.getValue();
    }

    // >>>> DEFAULTS >>>>
    protected List<Object> createDefaultList(int initSize) {
        return new ArrayList<Object>(initSize);
    }

    protected Set<Object> createDefaultSet(int initSize) {
        return new LinkedHashSet<Object>(initSize);
    }

    protected Map<Object, Object> createDefaultMap(int initSize) {
        // respect order from YAML document
        return new LinkedHashMap<Object, Object>(initSize);
    }

    protected Object createArray(Class<?> type, int size) {
        return Array.newInstance(type.getComponentType(), size);
    }

    // <<<< DEFAULTS <<<<

    protected Object finalizeConstruction(Node node, Object data) {
        final Class<? extends Object> type = node.getType();
        if (typeDefinitions.containsKey(type)) {
            return typeDefinitions.get(type).finalizeConstruction(data);
        }
        return data;
    }

    // >>>> NEW instance
    protected Object newInstance(Node node) {
        try {
            return newInstance(Object.class, node);
        } catch (InstantiationException e) {
            throw new YAMLException(e);
        }
    }

    final protected Object newInstance(Class<?> ancestor, Node node) throws InstantiationException {
        return newInstance(ancestor, node, true);
    }

    protected Object newInstance(Class<?> ancestor, Node node, boolean tryDefault)
            throws InstantiationException {
        final Class<? extends Object> type = node.getType();
        if (typeDefinitions.containsKey(type)) {
            TypeDescription td = typeDefinitions.get(type);
            final Object instance = td.newInstance(node);
            if (instance != null) {
                return instance;
            }
        }
        if (tryDefault) {
            /*
             * Removed <code> have InstantiationException in case of abstract
             * type
             */
            if (ancestor.isAssignableFrom(type) && !Modifier.isAbstract(type.getModifiers())) {
                try {
                    java.lang.reflect.Constructor<?> c = type.getDeclaredConstructor();
                    c.setAccessible(true);
                    return c.newInstance();
                } catch (NoSuchMethodException e) {
                    throw new InstantiationException("NoSuchMethodException:"
                            + e.getLocalizedMessage());
                } catch (Exception e) {
                    throw new YAMLException(e);
                }
            }
        }
        throw new InstantiationException();
    }

    @SuppressWarnings("unchecked")
    protected Set<Object> newSet(CollectionNode<?> node) {
        try {
            return (Set<Object>) newInstance(Set.class, node);
        } catch (InstantiationException e) {
            return createDefaultSet(node.getValue().size());
        }
    }

    @SuppressWarnings("unchecked")
    protected List<Object> newList(SequenceNode node) {
        try {
            return (List<Object>) newInstance(List.class, node);
        } catch (InstantiationException e) {
            return createDefaultList(node.getValue().size());
        }
    }

    @SuppressWarnings("unchecked")
    protected Map<Object, Object> newMap(MappingNode node) {
        try {
            return (Map<Object, Object>) newInstance(Map.class, node);
        } catch (InstantiationException e) {
            return createDefaultMap(node.getValue().size());
        }
    }

    // <<<< NEW instance

    // >>>> Construct => NEW, 2ndStep(filling)
    protected List<? extends Object> constructSequence(SequenceNode node) {
        List<Object> result = newList(node);
        constructSequenceStep2(node, result);
        return result;
    }

    protected Set<? extends Object> constructSet(SequenceNode node) {
        Set<Object> result = newSet(node);
        constructSequenceStep2(node, result);
        return result;
    }

    protected Object constructArray(SequenceNode node) {
        return constructArrayStep2(node, createArray(node.getType(), node.getValue().size()));
    }

    protected void constructSequenceStep2(SequenceNode node, Collection<Object> collection) {
        for (Node child : node.getValue()) {
            collection.add(constructObject(child));
        }
    }

    protected Object constructArrayStep2(SequenceNode node, Object array) {
        final Class<?> componentType = node.getType().getComponentType();

        int index = 0;
        for (Node child : node.getValue()) {
            // Handle multi-dimensional arrays...
            if (child.getType() == Object.class) {
                child.setType(componentType);
            }

            final Object value = constructObject(child);

            if (componentType.isPrimitive()) {
                // Null values are disallowed for primitives
                if (value == null) {
                    throw new NullPointerException(
                            "Unable to construct element value for " + child);
                }

                // Primitive arrays require quite a lot of work.
                if (byte.class.equals(componentType)) {
                    Array.setByte(array, index, ((Number) value).byteValue());

                } else if (short.class.equals(componentType)) {
                    Array.setShort(array, index, ((Number) value).shortValue());

                } else if (int.class.equals(componentType)) {
                    Array.setInt(array, index, ((Number) value).intValue());

                } else if (long.class.equals(componentType)) {
                    Array.setLong(array, index, ((Number) value).longValue());

                } else if (float.class.equals(componentType)) {
                    Array.setFloat(array, index, ((Number) value).floatValue());

                } else if (double.class.equals(componentType)) {
                    Array.setDouble(array, index, ((Number) value).doubleValue());

                } else if (char.class.equals(componentType)) {
                    Array.setChar(array, index, ((Character) value).charValue());

                } else if (boolean.class.equals(componentType)) {
                    Array.setBoolean(array, index, ((Boolean) value).booleanValue());

                } else {
                    throw new YAMLException("unexpected primitive type");
                }

            } else {
                // Non-primitive arrays can simply be assigned:
                Array.set(array, index, value);
            }

            ++index;
        }
        return array;
    }

    protected Set<Object> constructSet(MappingNode node) {
        final Set<Object> set = newSet(node);
        constructSet2ndStep(node, set);
        return set;
    }

    protected Map<Object, Object> constructMapping(MappingNode node) {
        final Map<Object, Object> mapping = newMap(node);
        constructMapping2ndStep(node, mapping);
        return mapping;
    }

    protected void constructMapping2ndStep(MappingNode node, Map<Object, Object> mapping) {
        List<NodeTuple> nodeValue = node.getValue();
        for (NodeTuple tuple : nodeValue) {
            Node keyNode = tuple.getKeyNode();
            Node valueNode = tuple.getValueNode();
            Object key = constructObject(keyNode);
            if (key != null) {
                try {
                    key.hashCode();// check circular dependencies
                } catch (Exception e) {
                    throw new ConstructorException("while constructing a mapping",
                            node.getStartMark(), "found unacceptable key " + key,
                            tuple.getKeyNode().getStartMark(), e);
                }
            }
            Object value = constructObject(valueNode);
            if (keyNode.isTwoStepsConstruction()) {
                if (loadingConfig.getAllowRecursiveKeys()) {
                    postponeMapFilling(mapping, key, value);
                } else {
                    throw new YAMLException("Recursive key for mapping is detected but it is not configured to be allowed.");
                }
            } else {
                mapping.put(key, value);
            }
        }
    }

    /*
     * if keyObject is created it 2 steps we should postpone putting
     * it in map because it may have different hash after
     * initialization compared to clean just created one. And map of
     * course does not observe key hashCode changes.
     */
    protected void postponeMapFilling(Map<Object, Object> mapping, Object key, Object value) {
        maps2fill.add(0, new RecursiveTuple(mapping, new RecursiveTuple(key, value)));
    }

    protected void constructSet2ndStep(MappingNode node, Set<Object> set) {
        List<NodeTuple> nodeValue = node.getValue();
        for (NodeTuple tuple : nodeValue) {
            Node keyNode = tuple.getKeyNode();
            Object key = constructObject(keyNode);
            if (key != null) {
                try {
                    key.hashCode();// check circular dependencies
                } catch (Exception e) {
                    throw new ConstructorException("while constructing a Set", node.getStartMark(),
                            "found unacceptable key " + key, tuple.getKeyNode().getStartMark(), e);
                }
            }
            if (keyNode.isTwoStepsConstruction()) {
                postponeSetFilling(set, key);
            } else {
                set.add(key);
            }
        }
    }

    /*
     * if keyObject is created it 2 steps we should postpone putting
     * it into the set because it may have different hash after
     * initialization compared to clean just created one. And set of
     * course does not observe value hashCode changes.
     */
    protected void postponeSetFilling(Set<Object> set, Object key) {
        sets2fill.add(0, new RecursiveTuple<Set<Object>, Object>(set, key));
    }

    // <<<< Costruct => NEW, 2ndStep(filling)

    // TODO protected List<Object[]> constructPairs(MappingNode node) {
    // List<Object[]> pairs = new LinkedList<Object[]>();
    // List<Node[]> nodeValue = (List<Node[]>) node.getValue();
    // for (Iterator<Node[]> iter = nodeValue.iterator(); iter.hasNext();) {
    // Node[] tuple = iter.next();
    // Object key = constructObject(Object.class, tuple[0]);
    // Object value = constructObject(Object.class, tuple[1]);
    // pairs.add(new Object[] { key, value });
    // }
    // return pairs;
    // }

    public void setPropertyUtils(PropertyUtils propertyUtils) {
        this.propertyUtils = propertyUtils;
        explicitPropertyUtils = true;
        Collection<TypeDescription> tds = typeDefinitions.values();
        for (TypeDescription typeDescription : tds) {
            typeDescription.setPropertyUtils(propertyUtils);
        }
    }

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

    
Make YAML aware how to parse a custom Class. If there is no root Class
assigned in constructor then the 'root' property of this definition is
respected.
Params:
definition – to be added to the Constructor
Returns:
the previous value associated with definition, or
null if there was no mapping for definition./**
     * Make YAML aware how to parse a custom Class. If there is no root Class
     * assigned in constructor then the 'root' property of this definition is
     * respected.
     *
     * @param definition to be added to the Constructor
     * @return the previous value associated with <code>definition</code>, or
     * <code>null</code> if there was no mapping for <code>definition</code>.
     */
    public TypeDescription addTypeDescription(TypeDescription definition) {
        if (definition == null) {
            throw new NullPointerException("TypeDescription is required.");
        }
        Tag tag = definition.getTag();
        typeTags.put(tag, definition.getType());
        definition.setPropertyUtils(getPropertyUtils());
        return typeDefinitions.put(definition.getType(), definition);
    }

    private static class RecursiveTuple<T, K> {
        private final T _1;
        private final K _2;

        public RecursiveTuple(T _1, K _2) {
            this._1 = _1;
            this._2 = _2;
        }

        public K _2() {
            return _2;
        }

        public T _1() {
            return _1;
        }
    }

    public final boolean isExplicitPropertyUtils() {
        return explicitPropertyUtils;
    }

    public boolean isAllowDuplicateKeys() {
        return allowDuplicateKeys;
    }

    public void setAllowDuplicateKeys(boolean allowDuplicateKeys) {
        this.allowDuplicateKeys = allowDuplicateKeys;
    }

    public boolean isWrappedToRootException() {
        return wrappedToRootException;
    }

    public void setWrappedToRootException(boolean wrappedToRootException) {
        this.wrappedToRootException = wrappedToRootException;
    }
}