/*
 * Copyright (C) 2004, 2005, 2006 Joe Walnes.
 * Copyright (C) 2006, 2007, 2008, 2009, 2011, 2013, 2016, 2017 XStream Committers.
 * All rights reserved.
 *
 * The software in this package is published under the terms of the BSD
 * style license a copy of which has been included with this distribution in
 * the LICENSE.txt file.
 * 
 * Created on 07. March 2004 by Joe Walnes
 */
package com.thoughtworks.xstream.core;

import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.ConverterLookup;
import com.thoughtworks.xstream.converters.ConverterRegistry;
import com.thoughtworks.xstream.core.util.PrioritizedList;
import com.thoughtworks.xstream.mapper.Mapper;

import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.WeakHashMap;

/**
 * The default implementation of converters lookup.
 * 
 * @author Joe Walnes
 * @author Jörg Schaible
 * @author Guilherme Silveira
 */
public class DefaultConverterLookup implements ConverterLookup, ConverterRegistry, Caching {

    private final PrioritizedList converters = new PrioritizedList();
    private transient Map typeToConverterMap;

    public DefaultConverterLookup() {
    	readResolve();
    }

    /**
     * @deprecated As of 1.3, use {@link #DefaultConverterLookup()}
     */
    public DefaultConverterLookup(Mapper mapper) {
    }

    public Converter lookupConverterForType(Class type) {
        Converter cachedConverter = (Converter) typeToConverterMap.get(type);
        if (cachedConverter != null) {
            return cachedConverter;
        }

        final Map errors = new LinkedHashMap();
        Iterator iterator = converters.iterator();
        while (iterator.hasNext()) {
            Converter converter = (Converter) iterator.next();
            try {
                if (converter.canConvert(type)) {
                    typeToConverterMap.put(type, converter);
                    return converter;
                }
            } catch (final RuntimeException e) {
                errors.put(converter.getClass().getName(), e.getMessage());
            } catch (final LinkageError e) {
                errors.put(converter.getClass().getName(), e.getMessage());
            }
        }

        final ConversionException exception = new ConversionException(errors.isEmpty()
            ? "No converter specified"
            : "No converter available");
        exception.add("type", type.getName());
        iterator = errors.entrySet().iterator();
        while (iterator.hasNext()) {
            final Map.Entry entry = (Map.Entry)iterator.next();
            exception.add("converter", entry.getKey().toString());
            exception.add("message", entry.getValue().toString());
        }
        throw exception;
    }
    
    public void registerConverter(Converter converter, int priority) {
        converters.add(converter, priority);
        for (Iterator iter = typeToConverterMap.keySet().iterator(); iter.hasNext();) {
            Class type = (Class) iter.next();
            try {
                if (converter.canConvert(type)) {
                    iter.remove();
                }
            } catch (final RuntimeException e) {
                // ignore
            } catch (final LinkageError e) {
                // ignore
            }
        }
    }
    
    public void flushCache() {
        typeToConverterMap.clear();
        Iterator iterator = converters.iterator();
        while (iterator.hasNext()) {
            Converter converter = (Converter) iterator.next();
            if (converter instanceof Caching) {
                ((Caching)converter).flushCache();
            }
        }
    }

    private Object readResolve() {
        typeToConverterMap = Collections.synchronizedMap(new WeakHashMap());
        return this;
    }
}