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Pax Wicket Service is an OSGi extension of the Wicket framework, allowing for dynamic loading and unloading of Wicket components and pageSources.
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/*
 * 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.wicket.validation;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.wicket.util.lang.Classes;

/**
 * A versatile implementation of {@link IValidationError} that supports message resolution from
 * {@link IErrorMessageSource}, default message (if none of the keys matched), and variable
 * substitution.
 * 
 * The final error message is constructed via the following process:
 * 
 * Try all keys added by calls to {@link #addMessageKey(String)} via the provided
 * IErrorMessageSource.
 * If none of the keys yielded a message, use the message set by {@link #setMessage(String)}, if
 * any.
 * Perform variable substitution on the message, if any.
 * 
 * 
 * @author Igor Vaynberg (ivaynberg)
 * @since 1.2.6
 */
public class ValidationError implements IValidationError
{
	private static final long serialVersionUID = 1L;

	private static final Map EMPTY_VARS = Collections.emptyMap();

	// XXX 2.0: optimization - keys can be null by default until a key is added
	/** list of message keys to try against the IErrorMessageSource */
	private final List keys = new ArrayList(1);

	/** variables map to use in variable substitution */
	private Map vars;

	/** default message used when all keys yield no message */
	private String message;

	/**
	 * Constructor.
	 */
	public ValidationError()
	{

	}

	/**
	 * Adds a key to the list of keys that will be tried against IErrorMessageSource to
	 * locate the error message string.
	 * 
	 * @param key
	 *            a message key to be added
	 * @return this ValidationError for chaining purposes
	 */
	public ValidationError addMessageKey(String key)
	{
		if (key == null || key.trim().length() == 0)
		{
			throw new IllegalArgumentException("Argument [[key]] cannot be null or an empty string");
		}
		keys.add(key);
		return this;
	}

	/**
	 * Sets a key and value in the variables map for use in substitution.
	 * 
	 * @param name
	 *            a variable name
	 * @param value
	 *            a variable value
	 * @return this ValidationError for chaining purposes
	 */
	public ValidationError setVariable(String name, Object value)
	{
		if (name == null || name.trim().length() == 0)
		{
			throw new IllegalArgumentException(
				"Argument [[name]] cannot be null or an empty string");
		}
		if (value == null)
		{
			throw new IllegalArgumentException(
				"Argument [[value]] cannot be null or an empty string");
		}

		getVariables().put(name, value);

		return this;
	}

	/**
	 * Retrieves the variables map for this error. The caller is free to modify the contents.
	 * 
	 * @return a Map of variables for this error
	 */
	public final Map getVariables()
	{
		if (vars == null)
		{
			vars = new HashMap(2);
		}
		return vars;
	}

	/**
	 * Sets the variables map for this error.
	 * 
	 * @param vars
	 *            a variables map
	 * @return this ValidationError for chaining purposes
	 */
	public final ValidationError setVariables(Map vars)
	{
		if (vars == null)
		{
			throw new IllegalArgumentException("Argument `vars` cannot be null");
		}
		this.vars = vars;
		return this;
	}

	/**
	 * @see IValidationError#getErrorMessage(IErrorMessageSource)
	 */
	public final String getErrorMessage(IErrorMessageSource messageSource)
	{
		String errorMessage = null;

		// try any message keys ...
		for (Iterator iterator = keys.iterator(); iterator.hasNext();)
		{
			errorMessage = messageSource.getMessage(iterator.next());
			if (errorMessage != null)
			{
				break;
			}
		}

		// ... if no keys matched try the default
		if (errorMessage == null && message != null)
		{
			errorMessage = message;
		}

		// if a message was found perform variable substitution
		if (errorMessage != null)
		{
			final Map p = (vars != null) ? vars : EMPTY_VARS;
			errorMessage = messageSource.substitute(errorMessage, p);
		}
		return errorMessage;
	}

	/**
	 * Gets the default message that will be used when no message could be located via message keys.
	 * 
	 * @return message the default message used when all keys yield no message
	 */
	public final String getMessage()
	{
		return message;
	}

	/**
	 * Sets message that will be used when no message could be located via message keys.
	 * 
	 * @param message
	 *            a default message to be used when all keys yield no message
	 * 
	 * @return this ValidationError for chaining purposes
	 */
	public final ValidationError setMessage(String message)
	{
		if (message == null)
		{
			throw new IllegalArgumentException("Argument [[defaultMessage]] cannot be null");
		}
		this.message = message;
		return this;
	}


	/**
	 * Gets error keys.
	 * 
	 * @return keys
	 */
	public List getKeys()
	{
		if (keys == null)
		{
			return Collections.emptyList();
		}
		else
		{
			return Collections.unmodifiableList(keys);
		}
	}

	/**
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString()
	{
		StringBuffer tostring = new StringBuffer();
		tostring.append("[").append(Classes.simpleName(getClass()));

		tostring.append(" message=[").append(message);

		tostring.append("], keys=[");
		if (keys != null)
		{
			Iterator i = keys.iterator();
			while (i.hasNext())
			{
				tostring.append(i.next());
				if (i.hasNext())
				{
					tostring.append(", ");
				}
			}
		}
		else
		{
			tostring.append("null");
		}
		tostring.append("], variables=[");

		if (vars != null)
		{
			Iterator> i = vars.entrySet().iterator();
			while (i.hasNext())
			{
				final Entry e = i.next();
				tostring.append("[")
					.append(e.getKey())
					.append("=")
					.append(e.getValue())
					.append("]");
				if (i.hasNext())
				{
					tostring.append(",");
				}
			}
		}
		else
		{
			tostring.append("null");
		}
		tostring.append("]");

		tostring.append("]");

		return tostring.toString();
	}

}