/*
 * 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.myfaces.taglib.core;

import javax.el.ELContext;
import javax.el.ValueExpression;
import javax.faces.application.Application;
import javax.faces.application.FacesMessage;
import javax.faces.component.StateHolder;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.validator.Validator;
import javax.faces.validator.ValidatorException;

/**
 * This class is used in conjunction with ValidatorImplTag. 
 * 
 * When a tag like this is in a jsp page:
 * 
 * <code>
 * &lt;f:validator binding="#{mybean}"/&gt;
 *  
 *  or
 *  
 * &lt;f:validator validatorId="#{'anyid'}" binding="#{mybean}"/&gt;
 * </code>
 * 
 * The value of mybean could be already on the context, so this
 * converter avoid creating a new variable and use the previous one.
 *
 * @author Leonardo Uribe (latest modification by $Author$)
 * @version $Revision$ $Date$
 *
 */
public class DelegateValidator implements Validator, StateHolder
{

    private ValueExpression _validatorId;
    private ValueExpression _binding;
    private String _validatorIdString = null;
    
    public DelegateValidator()
    {
        
    }
    
    public DelegateValidator(ValueExpression id, ValueExpression binding, String converterIdString)
    {
        super();
        _validatorId = id;
        _binding = binding;
        _validatorIdString = converterIdString;
    }

    @Override
    public boolean isTransient()
    {
        return false;
    }

    @Override
    public void restoreState(FacesContext facesContext, Object state)
    {
        Object[] values = (Object[]) state;
        _validatorId = (ValueExpression) values[0];
        _binding = (ValueExpression) values[1];
        _validatorIdString = (String) values[2];
    }

    @Override
    public Object saveState(FacesContext facesContext)
    {
        Object[] values = new Object[3];
        values[0] = _validatorId;
        values[1] = _binding;
        values[2] = _validatorIdString;
        return values;
    }

    @Override
    public void setTransient(boolean arg0)
    {
        // Do nothing        
    }

    private Validator _getDelegate()
    {
        return _createValidator();
    }

    private Validator _createValidator()
    {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        ELContext elContext = facesContext.getELContext();
        if (null != _binding)
        {
            Object validator;
            try
            {
                validator = _binding.getValue(elContext);
            }
            catch (Exception e)
            {
                throw new ValidatorException(new FacesMessage("Error while creating the Validator"), e);
            }
            if (validator instanceof Validator)
            {
                return (Validator) validator;
            }
        }
        Application application = facesContext.getApplication();
        Validator validator = null;
        try
        {
            // first check if an ValidatorId was set by a method
            if (null != _validatorIdString)
            {
                validator = application.createValidator(_validatorIdString);
            }
            else if (null != _validatorId)
            {
                String validatorId = (String) _validatorId.getValue(elContext);
                validator = application.createValidator(validatorId);
            }
        }
        catch (Exception e)
        {
            throw new ValidatorException(new FacesMessage("Error while creating the Validator"), e);
        }

        if (null != validator)
        {
            if (null != _binding)
            {
                _binding.setValue(elContext, validator);
            }
            return validator;
        }
        throw new ValidatorException(new FacesMessage("validatorId and/or binding must be specified"));
    }

    @Override
    public void validate(FacesContext facesContext, UIComponent component, Object value)
            throws ValidatorException
    {
        _getDelegate().validate(facesContext, component, value);
    }

}