/*
 * Copyright 2004-2014 the original author or authors.
 *
 * 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.springframework.webflow.context.servlet;

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

import javax.servlet.http.HttpServletRequest;

import org.springframework.binding.collection.StringKeyedMapAdapter;
import org.springframework.util.Assert;
import org.springframework.util.CompositeIterator;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;
import org.springframework.webflow.core.collection.CollectionUtils;

/**
 * Map backed by the Servlet HTTP request parameter map for accessing request parameters. Also provides support for
 * multi-part requests, providing transparent access to the request "fileMap" as a request parameter entry.
 *
 * @author Keith Donald
 */
public class HttpServletRequestParameterMap extends StringKeyedMapAdapter<Object> {

	/**
	 * The wrapped HTTP request.
	 */
	private HttpServletRequest request;

	/**
	 * Create a new map wrapping the parameters of given request.
	 */
	public HttpServletRequestParameterMap(HttpServletRequest request) {
		Assert.notNull(request, "The HTTP servlet request is required");
		this.request = request;
	}

	protected Object getAttribute(String key) {
		if (request instanceof MultipartHttpServletRequest) {
			MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
			List<MultipartFile> data = multipartRequest.getMultiFileMap().get(key);
			if (data != null && data.size() > 0) {
				if (data.size() == 1) {
					return data.get(0);
				} else {
					return data;
				}
			}
		}
		String[] parameters = request.getParameterValues(key);
		if (parameters == null) {
			return null;
		} else if (parameters.length == 1) {
			return parameters[0];
		} else {
			return parameters;
		}
	}

	protected void setAttribute(String key, Object value) {
		throw new UnsupportedOperationException("HttpServletRequest parameter maps are immutable");
	}

	protected void removeAttribute(String key) {
		throw new UnsupportedOperationException("HttpServletRequest parameter maps are immutable");
	}

	protected Iterator<String> getAttributeNames() {
		if (request instanceof MultipartHttpServletRequest) {
			MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
			CompositeIterator<String> iterator = new CompositeIterator<String>();
			iterator.add(multipartRequest.getFileMap().keySet().iterator());
			iterator.add(getRequestParameterNames());
			return iterator;
		} else {
			return getRequestParameterNames();
		}
	}

	private Iterator<String> getRequestParameterNames() {
		return CollectionUtils.toIterator(request.getParameterNames());
	}
}