/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * 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 io.undertow.servlet.attribute;

import io.undertow.attribute.ExchangeAttribute;
import io.undertow.attribute.ExchangeAttributeBuilder;
import io.undertow.attribute.ReadOnlyAttributeException;
import io.undertow.server.HttpServerExchange;
import io.undertow.servlet.handlers.ServletRequestContext;

/**
 * An attribute in the servlet request
 *
 * @author Stuart Douglas
 */
public class ServletRequestParameterAttribute implements ExchangeAttribute {

    private final String attributeName;

    public ServletRequestParameterAttribute(final String attributeName) {
        this.attributeName = attributeName;
    }

    @Override
    public String readAttribute(final HttpServerExchange exchange) {
        ServletRequestContext context = exchange.getAttachment(ServletRequestContext.ATTACHMENT_KEY);
        if (context != null) {
            Object result = context.getServletRequest().getParameter(attributeName);
            if (result != null) {
                return result.toString();
            }
        }
        return null;
    }

    @Override
    public void writeAttribute(final HttpServerExchange exchange, final String newValue) throws ReadOnlyAttributeException {
        throw new ReadOnlyAttributeException();
    }

    @Override
    public String toString() {
        return "%{rp," + attributeName + "}";
    }

    public static final class Builder implements ExchangeAttributeBuilder {

        @Override
        public String name() {
            return "Servlet request parameter";
        }

        @Override
        public ExchangeAttribute build(final String token) {
            if (token.startsWith("%{rp,") && token.endsWith("}")) {
                final String attributeName = token.substring(5, token.length() - 1);
                return new ServletRequestParameterAttribute(attributeName);
            }
            return null;
        }

        @Override
        public int priority() {
            return 0;
        }
    }
}
