/*
 * Copyright 2002-2010 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.http.client;

import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.Proxy;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;

import org.springframework.http.HttpMethod;
import org.springframework.util.Assert;

/**
 * {@link ClientHttpRequestFactory} implementation that uses standard J2SE facilities.
 *
 * @author Arjen Poutsma
 * @see java.net.HttpURLConnection
 * @see CommonsClientHttpRequestFactory
 * @since 3.0
 */
public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory {

	private Proxy proxy;

	/**
	 * Sets the {@link Proxy} to use for this request factory.
	 */
	public void setProxy(Proxy proxy) {
		this.proxy = proxy;
	}

	public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
		HttpURLConnection connection = openConnection(uri.toURL(), proxy);
		prepareConnection(connection, httpMethod.name());
		return new SimpleClientHttpRequest(connection);
	}

	/**
	 * Opens and returns a connection to the given URL.
	 * <p>The default implementation uses the given {@linkplain #setProxy(java.net.Proxy) proxy} - if any - to open a
	 * connection.
	 *
	 * @param url the URL to open a connection to
	 * @param proxy the proxy to use, may be {@code null}
	 * @return the opened connection
	 * @throws IOException in case of I/O errors
	 */
	protected HttpURLConnection openConnection(URL url, Proxy proxy) throws IOException {
		URLConnection urlConnection = proxy != null ? url.openConnection(proxy) : url.openConnection();
		Assert.isInstanceOf(HttpURLConnection.class, urlConnection);
		return (HttpURLConnection) urlConnection;
	}

	/**
	 * Template method for preparing the given {@link HttpURLConnection}.
	 * <p>The default implementation prepares the connection for input and output, and sets the HTTP method.
	 *
	 * @param connection the connection to prepare
	 * @param httpMethod the HTTP request method ({@code GET}, {@code POST}, etc.)
	 * @throws IOException in case of I/O errors
	 */
	protected void prepareConnection(HttpURLConnection connection, String httpMethod) throws IOException {
		connection.setDoInput(true);
		if ("GET".equals(httpMethod)) {
			connection.setInstanceFollowRedirects(true);
		}
		else {
			connection.setInstanceFollowRedirects(false);
		}
		if ("PUT".equals(httpMethod) || "POST".equals(httpMethod)) {
			connection.setDoOutput(true);
		}
		else {
			connection.setDoOutput(false);
		}
		connection.setRequestMethod(httpMethod);
	}

}