//  Copyright 2004 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.tapestry.script;

import org.apache.tapestry.IResourceResolver;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.util.xml.BaseRule;
import org.apache.tapestry.util.xml.DocumentParseException;
import org.apache.tapestry.util.xml.RuleDirectedParser;
import org.xml.sax.Attributes;

/**
 * Constructs an {@link org.apache.tapestry.script.InputSymbolToken}
 * from an &lt;input-symbol&gt; element.
 *
 * @author Howard Lewis Ship
 * @version $Id$
 * @since 3.0
 */
class InputSymbolRule extends BaseRule
{
    private IResourceResolver _resolver;

    public InputSymbolRule(IResourceResolver resolver)
    {
        _resolver = resolver;
    }

    public void startElement(RuleDirectedParser parser, Attributes attributes)
    {
        String key = getAttribute(attributes, "key");

        parser.validate(key, Tapestry.SIMPLE_PROPERTY_NAME_PATTERN, "ScriptParser.invalid-key");

        String className = getAttribute(attributes, "class");
        Class expectedClass = lookupClass(parser, className);

        String required = getAttribute(attributes, "required");

        InputSymbolToken token =
            new InputSymbolToken(key, expectedClass, required.equals("yes"), parser.getLocation());

        IScriptToken parent = (IScriptToken) parser.peek();
        parent.addToken(token);
    }

    private Class lookupClass(RuleDirectedParser parser, String className)
    {
        if (Tapestry.isBlank(className))
            return null;

        try
        {
            return _resolver.findClass(className);
        }
        catch (Exception ex)
        {
            throw new DocumentParseException(
                Tapestry.format("ScriptParser.unable-to-resolve-class", className),
                parser.getDocumentLocation(),
                parser.getLocation(),
                ex);
        }
    }
}