// Copyright 2007, 2008, 2010 The Apache Software Foundation
//
// 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.apache.tapestry5.internal.services;

import org.apache.tapestry5.*;
import org.apache.tapestry5.commons.services.PropertyAccess;
import org.apache.tapestry5.commons.services.TypeCoercer;
import org.apache.tapestry5.commons.util.ExceptionUtils;
import org.apache.tapestry5.internal.util.Holder;
import org.apache.tapestry5.ioc.internal.util.InternalUtils;

@SuppressWarnings("all")
public class FieldValidationSupportImpl implements FieldValidationSupport
{
    private final TypeCoercer typeCoercer;

    private final PropertyAccess propertyAccess;

    public FieldValidationSupportImpl(TypeCoercer typeCoercer, PropertyAccess propertyAccess)
    {
        this.typeCoercer = typeCoercer;
        this.propertyAccess = propertyAccess;
    }

    public String toClient(Object value, ComponentResources componentResources, FieldTranslator<Object> translator,
                           NullFieldStrategy nullFieldStrategy)
    {
        assert componentResources != null;
        assert translator != null;
        assert nullFieldStrategy != null;
        final Holder<String> resultHolder = Holder.create();

        ComponentEventCallback callback = new ComponentEventCallback()
        {
            public boolean handleResult(Object result)
            {
                // What's nice is that the ComponentEventException will automatically identify
                // the method description.

                if (!(result instanceof String))
                    throw new RuntimeException("Return value from 'parseClient' event handler method must be a string.");

                resultHolder.put((String) result);

                return true;
            }
        };

        componentResources.triggerEvent(EventConstants.TO_CLIENT, new Object[]
                {value}, callback);

        if (resultHolder.hasValue())
            return resultHolder.get();

        Object effectiveValue = value;

        if (effectiveValue == null)
        {
            effectiveValue = nullFieldStrategy.replaceToClient();

            // Don't try to coerce or translate null.

            if (effectiveValue == null)
                return null;
        }

        // And now, whether its a value from a bound property, or from the null field strategy,
        // get it into the right format for the translator and let it translate.

        Object coerced = typeCoercer.coerce(effectiveValue, translator.getType());

        return translator.toClient(coerced);
    }

    public Object parseClient(String clientValue, ComponentResources componentResources,
                              FieldTranslator<Object> translator, NullFieldStrategy nullFieldStrategy) throws ValidationException
    {
        assert componentResources != null;
        assert translator != null;
        assert nullFieldStrategy != null;
        String effectiveValue = clientValue;

        if (InternalUtils.isBlank(effectiveValue))
        {
            effectiveValue = nullFieldStrategy.replaceFromClient();

            if (effectiveValue == null)
                return null;
        }

        final Holder<Object> resultHolder = Holder.create();

        ComponentEventCallback callback = new ComponentEventCallback()
        {
            public boolean handleResult(Object result)
            {
                resultHolder.put(result);
                return true;
            }
        };

        try
        {
            componentResources.triggerEvent(EventConstants.PARSE_CLIENT, new Object[]
                    {effectiveValue}, callback);
        } catch (RuntimeException ex)
        {
            rethrowValidationException(ex);
        }

        if (resultHolder.hasValue())
            return resultHolder.get();

        return translator.parse(effectiveValue);
    }

    /**
     * Checks for a {@link org.apache.tapestry5.ValidationException} inside the outer exception and throws that,
     * otherwise rethrows the runtime exception.
     *
     * @param outerException initially caught exception
     * @throws ValidationException if found
     */
    private void rethrowValidationException(RuntimeException outerException) throws ValidationException
    {
        ValidationException ve = ExceptionUtils.findCause(outerException, ValidationException.class, propertyAccess);

        if (ve != null)
            throw ve;

        throw outerException;
    }

    @SuppressWarnings(
            {"unchecked"})
    public void validate(Object value, ComponentResources componentResources, FieldValidator validator)
            throws ValidationException
    {
        assert componentResources != null;
        assert validator != null;
        validator.validate(value);

        try
        {
            componentResources.triggerEvent(EventConstants.VALIDATE, new Object[]
                    {value}, null);
        } catch (RuntimeException ex)
        {
            rethrowValidationException(ex);
        }
    }
}
