/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.catalina.util;


import java.io.InputStream;
import java.util.Locale;
import java.util.Properties;

import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.compat.JreCompat;


/**
 * Utility class that attempts to map from a Locale to the corresponding character set to be used for interpreting input
 * text (or generating output text) when the Content-Type header does not include one. You can customize the behavior of
 * this class by modifying the mapping data it loads, or by subclassing it (to change the algorithm) and then using your
 * own version for a particular web application.
 */
public class CharsetMapper {


    // ---------------------------------------------------- Manifest Constants


    /**
     * Default properties resource name.
     */
    public static final String DEFAULT_RESOURCE = "/org/apache/catalina/util/CharsetMapperDefault.properties";


    // ---------------------------------------------------------- Constructors


    /**
     * Construct a new CharsetMapper using the default properties resource.
     */
    public CharsetMapper() {
        this(DEFAULT_RESOURCE);
    }


    /**
     * Construct a new CharsetMapper using the specified properties' resource.
     *
     * @param name Name of a properties resource to be loaded
     *
     * @exception IllegalArgumentException if the specified properties resource could not be loaded for any reason.
     */
    public CharsetMapper(String name) {
        if (JreCompat.isGraalAvailable()) {
            map.put("en", "ISO-8859-1");
        } else {
            try (InputStream stream = this.getClass().getResourceAsStream(name)) {
                map.load(stream);
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
                throw new IllegalArgumentException(t);
            }
        }
    }


    // ---------------------------------------------------- Instance Variables


    /**
     * The mapping properties that have been initialized from the specified or default properties resource.
     */
    private final Properties map = new Properties();


    // ------------------------------------------------------- Public Methods


    /**
     * Calculate the name of a character set to be assumed, given the specified Locale and the absence of a character
     * set specified as part of the content type header.
     *
     * @param locale The locale for which to calculate a character set
     *
     * @return the charset name
     */
    public String getCharset(Locale locale) {
        // Match full language_country_variant first, then language_country,
        // then language only
        String charset = map.getProperty(locale.toString());
        if (charset == null) {
            charset = map.getProperty(locale.getLanguage() + "_" + locale.getCountry());
            if (charset == null) {
                charset = map.getProperty(locale.getLanguage());
            }
        }
        return charset;
    }


    /**
     * The deployment descriptor can have a locale-encoding-mapping-list element which describes the webapp's desired
     * mapping from locale to charset. This method gets called when processing the web.xml file for a context
     *
     * @param locale  The locale for a character set
     * @param charset The charset to be associated with the locale
     */
    public void addCharsetMappingFromDeploymentDescriptor(String locale, String charset) {
        map.put(locale, charset);
    }


}
