/*
 * $Id$
 *
 * 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.struts2.util;

import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;
import com.opensymphony.xwork2.TextProvider;

import java.util.Iterator;
import java.util.List;
import java.util.LinkedList;
import java.util.Collections;

/**
 * Helper methods to access text from TextProviders
 */
public class TextProviderHelper {

    private static final Logger LOG = LoggerFactory.getLogger(TextProviderHelper.class);

     /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * The stack is searched if if no TextProvider is found, or the message is not found.
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found (evaluated for OGNL)
     * @param args            an array args to be used in a {@link java.text.MessageFormat} message
     * @param stack           the value stack to use for finding the text
     *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, List<Object> args, ValueStack stack) {
        return getText(key, defaultMessage, args, stack, true);
    }

    /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * <p>The search for a TextProvider is iterative from the root of the stack.</p>
     * <p>This method was refactored from  {@link org.apache.struts2.components.Text} to use a
     * consistent implementation across UIBean components.</p>
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found (evaluated for OGNL)
     * @param args            an array args to be used in a {@link java.text.MessageFormat} message
     * @param stack           the value stack to use for finding the text
     * @param searchStack     search stack for the key
     *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, List<Object> args, ValueStack stack, boolean searchStack) {
        String msg = null;
        TextProvider tp = null;

        for (Iterator iterator = stack.getRoot().iterator(); iterator.hasNext();) {
            Object o = iterator.next();

            if (o instanceof TextProvider) {
                tp = (TextProvider) o;
                msg = tp.getText(key, null, args, stack);

                break;
            }
        }

        if (msg == null) {
            // evaluate the defaultMesage as an OGNL expression
            if (searchStack)
                msg = stack.findString(defaultMessage);
            
            if (msg == null) {
                // use the defaultMessage literal value
                msg = defaultMessage;
            }

            if (LOG.isWarnEnabled()) {
                if (tp != null) {
                    LOG.warn("The first TextProvider in the ValueStack ("+tp.getClass().getName()+") could not locate the message resource with key '"+key+"'");
                } else {
                    LOG.warn("Could not locate the message resource '"+key+"' as there is no TextProvider in the ValueStack.");
                }
                if (msg.equals(defaultMessage)) {
                    LOG.warn("The default value expression '"+defaultMessage+"' was evaluated and did not match a property.  The literal value '"+defaultMessage+"' will be used.");
                } else {
                    LOG.warn("The default value expression '"+defaultMessage+"' evaluated to '"+msg+"'");
                }
            }
        }
        return msg;
    }

    /**
     * <p>Get a message from the first TextProvider encountered in the stack.
     * If the first TextProvider doesn't provide the message the default message is returned.</p>
     * <p>The search for a TextProvider is iterative from the root of the stack.</p>
     * <p>This method was refactored from  {@link org.apache.struts2.components.Text} to use a
     * consistent implementation across UIBean components.</p>
     * @param key             the message key in the resource bundle
     * @param defaultMessage  the message to return if not found
     * @param stack           the value stack to use for finding the text
       *
     * @return the message if found, otherwise the defaultMessage
     */
    public static String getText(String key, String defaultMessage, ValueStack stack) {
        return getText(key, defaultMessage, Collections.emptyList(), stack);
    }
}
