/*
 *  Copyright 2012 Anyware Services
 *
 *  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.ametys.core.util;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import org.apache.avalon.framework.activity.Disposable;
import org.apache.avalon.framework.activity.Initializable;
import org.apache.avalon.framework.component.Component;
import org.apache.avalon.framework.component.ComponentException;
import org.apache.avalon.framework.context.Context;
import org.apache.avalon.framework.context.ContextException;
import org.apache.avalon.framework.context.Contextualizable;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.Serviceable;
import org.apache.cocoon.components.ContextHelper;
import org.apache.cocoon.i18n.Bundle;
import org.apache.cocoon.i18n.BundleFactory;
import org.apache.cocoon.xml.ParamSaxBuffer;
import org.apache.cocoon.xml.SaxBuffer;
import org.apache.cocoon.xml.SaxBuffer.Characters;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import org.ametys.core.cocoon.XMLResourceBundle;
import org.ametys.runtime.i18n.I18nizableText;
import org.ametys.runtime.plugin.PluginsManager;
import org.ametys.runtime.workspace.WorkspaceManager;

/**
 * Utils for i18n
 */
public class I18nUtils extends AbstractLogEnabled implements Component, Serviceable, Contextualizable, Initializable, Disposable
{
    /** The avalon role */
    public static final String ROLE = I18nUtils.class.getName();
    
    private static I18nUtils _instance;
    
    /** I18n catalogues */
    protected Map<String, Location> _locations;
    
    /** The avalon context */
    protected Context _context;
    
    private BundleFactory _bundleFactory;
    
    // Map<language, Map<text, translatedValue>>
    private Map<String, Map<I18nizableText, String>> _cache;

    
    @Override
    public void contextualize(Context context) throws ContextException
    {
        _context = context;
    }
    
    @Override
    public void service(ServiceManager manager) throws ServiceException
    {
        _bundleFactory = (BundleFactory) manager.lookup(BundleFactory.ROLE);
    }
    
    @Override
    public void initialize() throws Exception
    {
        _instance = this;
        _cache = new HashMap<>();
        
        _configure();
    }
    
    /**
     * Configure the i18n catalogue
     */
    protected void _configure ()
    {
        _locations = new HashMap<>();
        
        // initializes locations
        
        _locations.put("application", new Location("application", new String[]{"context://WEB-INF/i18n"}));
        
        PluginsManager pm = PluginsManager.getInstance();
        
        for (String pluginName : pm.getPluginNames())
        {
            String id = "plugin." + pluginName;
            
            String location2 = "plugin:" + pluginName + "://i18n";

            _locations.put(id, new Location("messages", new String[]{"context://WEB-INF/i18n/plugins/" + pluginName, location2}));
        }

        WorkspaceManager wm = WorkspaceManager.getInstance();
        
        for (String workspace : wm.getWorkspaceNames())
        {
            String id = "workspace." + workspace;
            String location2 = "workspace:" + workspace + "://i18n";
           
            _locations.put(id, new Location("messages", new String[]{"context://WEB-INF/i18n/workspaces/" + workspace, location2}));
        }
    }
    
    /**
     * Reload the i18n catalogues and clear cache.
     * This method should be called as soon as the list of i18n catalogue was changed, when adding a new catalogue for example.
     */
    public void reloadCatalogues ()
    {
        clearCache();
        _configure();
    }
    
    /**
     * Get the unique instance
     * @return the unique instance
     */
    public static I18nUtils getInstance()
    {
        return _instance;
    }
    
    /**
     * Get the translation of the key.
     * This method is slow.
     * Only use in very specific cases (send mail for example)
     * @param text The i18n key to translate
     * @return The translation or null if there's no available translation
     * @throws IllegalStateException if an error occured
     */
    public String translate(I18nizableText text)
    {
        return translate(text, null);
    }
    
    /**
     * Get the translation of the key.
     * Only use in very specific cases (send mail for example)
     * @param text The i18n key to translate
     * @param language The language code to use for translation. Can be null.
     * @return The translation or null if there's no available translation
     * @throws IllegalStateException if an error occurred
     */
    public String translate(I18nizableText text, String language) throws IllegalStateException
    {
        return translate(text, language, false);
    }
    
    /**
     * Get the translation of the key.
     * Only use in very specific cases (send mail for example)
     * @param text The i18n key to translate
     * @param language The language code to use for translation. Can be null.
     * @param rawValue Set true to get the value corresponding strictly to the specified Locale, without escalading to parent Locale if not found. Note that there is no cache for strict values.
     * @return The translation or null if there's no available translation
     * @throws IllegalStateException if an error occurred
     */
    public String translate(I18nizableText text, String language, boolean rawValue) throws IllegalStateException
    {
        // Check language
        String langCode = language;
        if (langCode == null)
        {
            Map objectModel = ContextHelper.getObjectModel(_context);
            Locale locale = org.apache.cocoon.i18n.I18nUtils.findLocale(objectModel, "locale", null, Locale.getDefault(), true);
            langCode = locale.toString();
        }
        
        Map<I18nizableText, String> values = getLangCache(langCode);
        
        String value = null;
        
        if (rawValue)
        {
            // No cache for strict values
            value = _translate(text, langCode, true);
        }
        else if (values.containsKey(text))
        {
            value = values.get(text);
        }
        else
        {
            value = _translate(text, langCode, false);
            
            if (value != null)
            {
                // Put in cache
                values.put(text, value);
            }
        }

        return value;
    }
    
    /**
     * Clear the i18n cache.
     */
    public void clearCache()
    {
        _cache.clear();
    }
    
    /**
     * Get the translation cache for a language.
     * @param language the language.
     * @return the translation cache for the given language.
     */
    protected Map<I18nizableText, String> getLangCache(String language)
    {
        Map<I18nizableText, String> langCache;
        
        if (_cache.containsKey(language))
        {
            langCache = _cache.get(language);
        }
        else
        {
            langCache = new HashMap<>();
            _cache.put(language, langCache);
        }
        
        return langCache;
    }
    
    /**
     * Get the translation of the key.
     * Only use in very specific cases (send mail for example)
     * @param text The i18n key to translate
     * @param language The language code to use for translation. Can be null.
     * @param rawValue Set true to get the value corresponding strictly to the specified Locale, without escalading to parent Locale if not found 
     * @return The translation or null if there's no available translation
     * @throws IllegalStateException if an error occured
     */
    protected String _translate(I18nizableText text, String language, boolean rawValue) throws IllegalStateException
    {
        if (!text.isI18n())
        {            
            return text.getLabel();
        }
        
        Location location = null;
        if (text.getLocation() != null)
        {
            location = new Location(text.getBundleName(), new String[]{text.getLocation()});
        }
        else
        {
            String catalogue = text.getCatalogue();
            location = _locations.get(catalogue);
        }
        
        if (location == null)
        {
            return null;
        }
        
        try
        {
            Bundle bundle = _bundleFactory.select(location.getLocations(), location.getName(), org.apache.cocoon.i18n.I18nUtils.parseLocale(language));
            
            // translated message
            ParamSaxBuffer buffer = rawValue ? (ParamSaxBuffer) ((XMLResourceBundle) bundle).getRawObject(text.getKey()) : (ParamSaxBuffer) bundle.getObject(text.getKey());
            
            if (buffer == null)
            {
                return null;
            }
            
            // message parameters
            Map<String, SaxBuffer> params = new HashMap<>();
            
            if (text.getParameters() != null)
            {
                int p = 0;
                for (String param : text.getParameters())
                {
                    Characters characters = new Characters(param.toCharArray(), 0, param.length());
                    params.put(String.valueOf(p++), new SaxBuffer(Arrays.asList(characters)));
                }
            }
            
            if (text.getParameterMap() != null)
            {
                for (String name : text.getParameterMap().keySet())
                {
                    // named parameters are themselves I18nizableText, so translate them recursively
                    String param = translate(text.getParameterMap().get(name), language, rawValue);
                    if (param == null)
                    {
                        param = "";
                    }
                    Characters characters = new Characters(param.toCharArray(), 0, param.length());
                    params.put(name, new SaxBuffer(Arrays.asList(characters)));
                }
            }
            
            StringBuilder result = new StringBuilder();
            buffer.toSAX(new BufferHandler(result), params);
            
            return result.toString();
        }
        catch (SAXException e)
        {
            throw new RuntimeException("Unable to get i18n translation", e);
        }
        catch (ComponentException e)
        {
            throw new RuntimeException("Unable to get i18n catalogue", e);
        }
    }
    
    private class BufferHandler extends DefaultHandler
    {
        StringBuilder _builder;
        
        public BufferHandler(StringBuilder builder)
        {
            _builder = builder;
        }
        
        @Override
        public void characters(char[] ch, int start, int length) throws SAXException
        {
            _builder.append(ch, start, length);
        }
    }
    
    public void dispose()
    {
        _instance = null;
    }
    
    /**
     * Class representing an i18n location
     */
    protected class Location 
    {
        String[] _loc;
        String _name;
        
        /**
         * Constructor.
         * @param name the catalogue name
         * @param locations the files locations.
         */
        public Location (String name, String[] locations)
        {
            _name = name;
            _loc = locations;
        }
        
        /**
         * Get the name
         * @return the name
         */
        public String getName ()
        {
            return _name;
        }
        
        /**
         * Get the files location
         * @return the files location
         */
        public String[] getLocations()
        {
            return _loc;
        }
    }
}