package com.fasterxml.jackson.databind.ext;

import java.util.logging.Logger;
import java.util.logging.Level;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.Deserializers;
import com.fasterxml.jackson.databind.ser.Serializers;
import com.fasterxml.jackson.databind.util.ClassUtil;

Helper class used for isolating details of handling optional+external types
(javax.xml classes) from standard factories that offer them.

Note that 2.7 changed handling to slightly less dynamic, to avoid having to
traverse class hierarchy, which turned to be a performance issue in
certain cases. Since DOM classes are assumed to exist on all Java 1.6
environments (yes, even on Android/GAE), this part could be simplified by
slightly less dynamic lookups.

Also with 2.7 we are supporting JDK 1.7/Java 7 type(s).
/**
 * Helper class used for isolating details of handling optional+external types
 * (javax.xml classes) from standard factories that offer them.
 *<p>
 * Note that 2.7 changed handling to slightly less dynamic, to avoid having to
 * traverse class hierarchy, which turned to be a performance issue in
 * certain cases. Since DOM classes are assumed to exist on all Java 1.6
 * environments (yes, even on Android/GAE), this part could be simplified by
 * slightly less dynamic lookups.
 *<p>
 * Also with 2.7 we are supporting JDK 1.7/Java 7 type(s).
 */
public class OptionalHandlerFactory implements java.io.Serializable
{
    private static final long serialVersionUID = 1;

    /* To make 2 main "optional" handler groups (javax.xml.stream)
     * more dynamic, we better only figure out handlers completely dynamically, if and
     * when they are needed. To do this we need to assume package prefixes.
     */
    private final static String PACKAGE_PREFIX_JAVAX_XML = "javax.xml.";

    private final static String SERIALIZERS_FOR_JAVAX_XML = "com.fasterxml.jackson.databind.ext.CoreXMLSerializers";
    private final static String DESERIALIZERS_FOR_JAVAX_XML = "com.fasterxml.jackson.databind.ext.CoreXMLDeserializers";

    // Plus we also have a single serializer for DOM Node:
//    private final static String CLASS_NAME_DOM_NODE = "org.w3c.dom.Node";
//    private final static String CLASS_NAME_DOM_DOCUMENT = "org.w3c.dom.Document";
    private final static String SERIALIZER_FOR_DOM_NODE = "com.fasterxml.jackson.databind.ext.DOMSerializer";
    private final static String DESERIALIZER_FOR_DOM_DOCUMENT = "com.fasterxml.jackson.databind.ext.DOMDeserializer$DocumentDeserializer";
    private final static String DESERIALIZER_FOR_DOM_NODE = "com.fasterxml.jackson.databind.ext.DOMDeserializer$NodeDeserializer";

    // // Since 2.7, we will assume DOM classes are always found, both due to JDK 1.6 minimum
    // // and because Android (and presumably GAE) have these classes

    private final static Class<?> CLASS_DOM_NODE;
    private final static Class<?> CLASS_DOM_DOCUMENT;

    static {
        Class<?> doc = null, node = null;
        try {
            node = org.w3c.dom.Node.class;
            doc = org.w3c.dom.Document.class;
        } catch (Exception e) {
            // not optimal but will do
            Logger.getLogger(OptionalHandlerFactory.class.getName())
                .log(Level.INFO, "Could not load DOM `Node` and/or `Document` classes: no DOM support");
        }
        CLASS_DOM_NODE = node;
        CLASS_DOM_DOCUMENT = doc;
    }

    // // But Java7 type(s) may or may not be; dynamic lookup should be fine, still
    // // (note: also assume it comes from JDK so that ClassLoader issues with OSGi
    // // can, I hope, be avoided?)

    private static final Java7Support _jdk7Helper;
    static {
        Java7Support x = null;
        try {
            x = Java7Support.instance();
        } catch (Throwable t) { }
        _jdk7Helper = x;
    }
    
    public final static OptionalHandlerFactory instance = new OptionalHandlerFactory();
    
    protected OptionalHandlerFactory() { }

    /*
    /**********************************************************
    /* Public API
    /**********************************************************
     */
    
    public JsonSerializer<?> findSerializer(SerializationConfig config, JavaType type,
            BeanDescription beanDesc)
    {
        final Class<?> rawType = type.getRawClass();

        if (_jdk7Helper != null) {
            JsonSerializer<?> ser = _jdk7Helper.getSerializerForJavaNioFilePath(rawType);
            if (ser != null) {
                return ser;
            }
        }
        if ((CLASS_DOM_NODE != null) && CLASS_DOM_NODE.isAssignableFrom(rawType)) {
            return (JsonSerializer<?>) instantiate(SERIALIZER_FOR_DOM_NODE);
        }
        String className = rawType.getName();
        String factoryName;
        if (className.startsWith(PACKAGE_PREFIX_JAVAX_XML) || hasSuperClassStartingWith(rawType, PACKAGE_PREFIX_JAVAX_XML)) {
            factoryName = SERIALIZERS_FOR_JAVAX_XML;
        } else {
            return null;
        }

        Object ob = instantiate(factoryName);
        if (ob == null) { // could warn, if we had logging system (j.u.l?)
            return null;
        }
        return ((Serializers) ob).findSerializer(config, type, beanDesc);
    }

    public JsonDeserializer<?> findDeserializer(JavaType type, DeserializationConfig config,
            BeanDescription beanDesc)
        throws JsonMappingException
    {
        final Class<?> rawType = type.getRawClass();

        if (_jdk7Helper != null) {
            JsonDeserializer<?> deser = _jdk7Helper.getDeserializerForJavaNioFilePath(rawType);
            if (deser != null) {
                return deser;
            }
        }
        if ((CLASS_DOM_NODE != null) && CLASS_DOM_NODE.isAssignableFrom(rawType)) {
            return (JsonDeserializer<?>) instantiate(DESERIALIZER_FOR_DOM_NODE);
        }
        if ((CLASS_DOM_DOCUMENT != null) && CLASS_DOM_DOCUMENT.isAssignableFrom(rawType)) {
            return (JsonDeserializer<?>) instantiate(DESERIALIZER_FOR_DOM_DOCUMENT);
        }
        String className = rawType.getName();
        String factoryName;
        if (className.startsWith(PACKAGE_PREFIX_JAVAX_XML)
                || hasSuperClassStartingWith(rawType, PACKAGE_PREFIX_JAVAX_XML)) {
            factoryName = DESERIALIZERS_FOR_JAVAX_XML;
        } else {
            return null;
        }
        Object ob = instantiate(factoryName);
        if (ob == null) { // could warn, if we had logging system (j.u.l?)
            return null;
        }
        return ((Deserializers) ob).findBeanDeserializer(type, config, beanDesc);
    }
    
    /*
    /**********************************************************
    /* Internal helper methods
    /**********************************************************
     */

    private Object instantiate(String className)
    {
        try {
            return ClassUtil.createInstance(Class.forName(className), false);
        } catch (LinkageError e) { }
        // too many different kinds to enumerate here:
        catch (Exception e) { }
        return null;
    }

    
Since 2.7 we only need to check for class extension, as all implemented
types are classes, not interfaces. This has performance implications for
some cases, as we do not need to go over interfaces implemented, just
superclasses
Since:
2.7/**
     * Since 2.7 we only need to check for class extension, as all implemented
     * types are classes, not interfaces. This has performance implications for
     * some cases, as we do not need to go over interfaces implemented, just
     * superclasses
     * 
     * @since 2.7
     */
    private boolean hasSuperClassStartingWith(Class<?> rawType, String prefix)
    {
        for (Class<?> supertype = rawType.getSuperclass(); supertype != null; supertype = supertype.getSuperclass()) {
            if (supertype == Object.class) {
                return false;
            }
            if (supertype.getName().startsWith(prefix)) {
                return true;
            }
        }
        return false;
    }
}