/*
 * @(#)URLStringCatFunction.java
 *
 * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
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 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
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 *
 * You acknowledge that this software is not designed or intended for use in
 * the design, construction, operation or maintenance of any nuclear facility.
 */

package org.wso2.balana.cond;

import org.wso2.balana.ctx.EvaluationCtx;

import org.wso2.balana.attr.AnyURIAttribute;
import org.wso2.balana.attr.AttributeValue;
import org.wso2.balana.attr.StringAttribute;

import org.wso2.balana.ctx.Status;

import java.net.URI;
import java.net.URISyntaxException;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * Represents the XACML 2.0 url-string-concatenate function.
 * 
 * @since 2.0
 * @author Seth Proctor
 */
public class URLStringCatFunction extends FunctionBase {

	/**
	 * Standard identifier for the url-string-concatenate function.
	 */
	public static final String NAME_URI_STRING_CONCATENATE = FUNCTION_NS_2
			+ "uri-string-concatenate";

	/**
	 * Creates an instance of this function.
	 */
	public URLStringCatFunction() {
		super(NAME_URI_STRING_CONCATENATE, 0, AnyURIAttribute.identifier, false);
	}

	/**
	 * Checks the inputs of this function.
	 * 
	 * @param inputs a <code>List></code> of <code>Evaluatable</code>s
	 * 
	 * @throws IllegalArgumentException if the inputs won't work
	 */
	public void checkInputs(List inputs) throws IllegalArgumentException {
		// scan the list to make sure nothing returns a bag
		Iterator it = inputs.iterator();
		while (it.hasNext()) {
			if (((Expression) (it.next())).returnsBag())
				throw new IllegalArgumentException(NAME_URI_STRING_CONCATENATE
						+ " doesn't accept bags");
		}

		// nothing is a bag, so check using the no-bag method
		checkInputsNoBag(inputs);
	}

	/**
	 * Checks the inputs of this function assuming no parameters are bags.
	 * 
	 * @param inputs a <code>List></code> of <code>Evaluatable</code>s
	 * 
	 * @throws IllegalArgumentException if the inputs won't work
	 */
	public void checkInputsNoBag(List inputs) throws IllegalArgumentException {
		// make sure it's long enough
		if (inputs.size() < 2)
			throw new IllegalArgumentException("not enough args to " + NAME_URI_STRING_CONCATENATE);

		// check that the parameters are of the correct types...
		Iterator it = inputs.iterator();

		// ...the first argument must be a URI...
		if (!((Expression) (it.next())).getType().toString().equals(AnyURIAttribute.identifier))
			throw new IllegalArgumentException("illegal parameter");

		// ...and all following arguments must be strings
		while (it.hasNext()) {
			if (!((Expression) (it.next())).getType().toString().equals(StringAttribute.identifier))
				throw new IllegalArgumentException("illegal parameter");
		}
	}

	/**
	 * Evaluates the function given the input data. This function expects an
	 * <code>AnyURIAttribute</code> followed by one or more <code>StringAttribute</code>s, and
	 * returns an <code>AnyURIAttribute</code>.
	 * 
	 * @param inputs the input agrument list
	 * @param context the representation of the request
	 * 
	 * @return the result of evaluation
	 */
	public EvaluationResult evaluate(List inputs, EvaluationCtx context) {
		// Evaluate the arguments
		AttributeValue[] argValues = new AttributeValue[inputs.size()];
		EvaluationResult result = evalArgs(inputs, context, argValues);
		if (result != null)
			return result;

		// the first argument is always a URI
		String str = ((AnyURIAttribute) (argValues[0])).getValue().toString();

		// the remaining arguments are strings
		StringBuffer buffer = new StringBuffer(str);
		for (int i = 1; i < argValues.length; i++) {
			buffer.append(((StringAttribute) (argValues[i])).getValue());
		}

		// finally, try to convert the string back to a URI
		try {
			return new EvaluationResult(new AnyURIAttribute(new URI(str)));
		} catch (URISyntaxException use) {
			List code = new ArrayList();
			code.add(Status.STATUS_PROCESSING_ERROR);
			String message = NAME_URI_STRING_CONCATENATE + " didn't produce" + " a valid URI: "
					+ str;

			return new EvaluationResult(new Status(code, message));
		}
	}

}