package com.fasterxml.jackson.databind.deser.impl;

import java.io.IOException;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;

import com.fasterxml.jackson.annotation.ObjectIdGenerator;
import com.fasterxml.jackson.annotation.ObjectIdResolver;
import com.fasterxml.jackson.core.JsonLocation;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.deser.UnresolvedForwardReference;

Simple value container for containing information about single Object Id
during deserialization
/**
 * Simple value container for containing information about single Object Id
 * during deserialization
 */
public class ReadableObjectId
{
    
Since:
2.8 (with this name, formerly `public Object item`)/**
     * @since 2.8 (with this name, formerly `public Object item`)
     */
    protected Object _item;

    protected final ObjectIdGenerator.IdKey _key;

    protected LinkedList<Referring> _referringProperties;

    protected ObjectIdResolver _resolver;

    public ReadableObjectId(ObjectIdGenerator.IdKey key) {
        _key = key;
    }

    public void setResolver(ObjectIdResolver resolver) {
        _resolver = resolver;
    }

    public ObjectIdGenerator.IdKey getKey() {
        return _key;
    }

    public void appendReferring(Referring currentReferring) {
        if (_referringProperties == null) {
            _referringProperties = new LinkedList<Referring>();
        }
        _referringProperties.add(currentReferring);
    }

    
Method called to assign actual POJO to which ObjectId refers to: will
also handle referring properties, if any, by assigning POJO.
/**
     * Method called to assign actual POJO to which ObjectId refers to: will
     * also handle referring properties, if any, by assigning POJO.
     */
    public void bindItem(Object ob) throws IOException
    {
        _resolver.bindItem(_key, ob);
        _item = ob;
        Object id = _key.key;
        if (_referringProperties != null) {
            Iterator<Referring> it = _referringProperties.iterator();
            _referringProperties = null;
            while (it.hasNext()) {
                it.next().handleResolvedForwardReference(id, ob);
            }
        }
    }

    public Object resolve(){
         return (_item = _resolver.resolveId(_key));
    }

    public boolean hasReferringProperties() {
        return (_referringProperties != null) && !_referringProperties.isEmpty();
    }

    public Iterator<Referring> referringProperties() {
        if (_referringProperties == null) {
            return Collections.<Referring> emptyList().iterator();
        }
        return _referringProperties.iterator();
    }

    
Method called by DeserializationContext at the end of deserialization if this Object Id was not resolved during normal processing. Call is made to allow custom implementations to use alternative resolution strategies; currently the only way to make use of this functionality is by sub-classing ReadableObjectId and overriding this method. 

Default implementation simply returns false to indicate that resolution
attempt did not succeed. 
Returns:
True, if resolution succeeded (and no error needs to be reported); false to
  indicate resolution did not succeed.
Since:
2.6/**
     * Method called by {@link DeserializationContext} at the end of deserialization
     * if this Object Id was not resolved during normal processing. Call is made to
     * allow custom implementations to use alternative resolution strategies; currently
     * the only way to make use of this functionality is by sub-classing
     * {@link ReadableObjectId} and overriding this method.
     *<p>
     * Default implementation simply returns <code>false</code> to indicate that resolution
     * attempt did not succeed. 
     *
     * @return True, if resolution succeeded (and no error needs to be reported); false to
     *   indicate resolution did not succeed.
     *
     * @since 2.6
     */
    public boolean tryToResolveUnresolved(DeserializationContext ctxt)
    {
        return false;
    }

    
Allow access to the resolver in case anybody wants to use it directly, for examples from DefaultDeserializationContext.tryToResolveUnresolvedObjectId. 
Returns:
The registered resolver
Since:
2.7/**
     * Allow access to the resolver in case anybody wants to use it directly, for
     * examples from 
     * {@link com.fasterxml.jackson.databind.deser.DefaultDeserializationContext#tryToResolveUnresolvedObjectId}.
     *
     * @return The registered resolver
     * 
     * @since 2.7
     */
    public ObjectIdResolver getResolver() {
        return _resolver;
    }

    @Override
    public String toString() {
        return String.valueOf(_key);
    }

    /*
    /**********************************************************
    /* Helper classes
    /**********************************************************
     */

    public static abstract class Referring {
        private final UnresolvedForwardReference _reference;
        private final Class<?> _beanType;

        public Referring(UnresolvedForwardReference ref, Class<?> beanType) {
            _reference = ref;
            _beanType = beanType;
        }

        public Referring(UnresolvedForwardReference ref, JavaType beanType) {
            _reference = ref;
            _beanType = beanType.getRawClass();
        }

        public JsonLocation getLocation() { return _reference.getLocation(); }
        public Class<?> getBeanType() { return _beanType; }

        public abstract void handleResolvedForwardReference(Object id, Object value) throws IOException;
        public boolean hasId(Object id) {
            return id.equals(_reference.getUnresolvedId());
        }
    }
}