/*
 * Copyright 2002-2017 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
 *
 *      https://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.core.task.AsyncListenableTaskExecutor;
import org.springframework.http.HttpMethod;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

/**
 * {@link ClientHttpRequestFactory} implementation that uses standard JDK facilities.
 *
 * @author Arjen Poutsma
 * @author Juergen Hoeller
 * @since 3.0
 * @see java.net.HttpURLConnection
 * @see HttpComponentsClientHttpRequestFactory
 */
@SuppressWarnings("deprecation")
public class SimpleClientHttpRequestFactory implements ClientHttpRequestFactory, AsyncClientHttpRequestFactory {

        private static final int DEFAULT_CHUNK_SIZE = 4096;


        @Nullable
        private Proxy proxy;

        private boolean bufferRequestBody = true;

        private int chunkSize = DEFAULT_CHUNK_SIZE;

        private int connectTimeout = -1;

        private int readTimeout = -1;

        private boolean outputStreaming = true;

        @Nullable
        private AsyncListenableTaskExecutor taskExecutor;


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

        /**
         * Indicate whether this request factory should buffer the
         * {@linkplain ClientHttpRequest#getBody() request body} internally.
         * <p>Default is {@code true}. When sending large amounts of data via POST or PUT,
         * it is recommended to change this property to {@code false}, so as not to run
         * out of memory. This will result in a {@link ClientHttpRequest} that either
         * streams directly to the underlying {@link HttpURLConnection} (if the
         * {@link org.springframework.http.HttpHeaders#getContentLength() Content-Length}
         * is known in advance), or that will use "Chunked transfer encoding"
         * (if the {@code Content-Length} is not known in advance).
         * @see #setChunkSize(int)
         * @see HttpURLConnection#setFixedLengthStreamingMode(int)
         */
        public void setBufferRequestBody(boolean bufferRequestBody) {
                this.bufferRequestBody = bufferRequestBody;
        }

        /**
         * Set the number of bytes to write in each chunk when not buffering request
         * bodies locally.
         * <p>Note that this parameter is only used when
         * {@link #setBufferRequestBody(boolean) bufferRequestBody} is set to {@code false},
         * and the {@link org.springframework.http.HttpHeaders#getContentLength() Content-Length}
         * is not known in advance.
         * @see #setBufferRequestBody(boolean)
         */
        public void setChunkSize(int chunkSize) {
                this.chunkSize = chunkSize;
        }

        /**
         * Set the underlying URLConnection's connect timeout (in milliseconds).
         * A timeout value of 0 specifies an infinite timeout.
         * <p>Default is the system's default timeout.
         * @see URLConnection#setConnectTimeout(int)
         */
        public void setConnectTimeout(int connectTimeout) {
                this.connectTimeout = connectTimeout;
        }

        /**
         * Set the underlying URLConnection's read timeout (in milliseconds).
         * A timeout value of 0 specifies an infinite timeout.
         * <p>Default is the system's default timeout.
         * @see URLConnection#setReadTimeout(int)
         */
        public void setReadTimeout(int readTimeout) {
                this.readTimeout = readTimeout;
        }

        /**
         * Set if the underlying URLConnection can be set to 'output streaming' mode.
         * Default is {@code true}.
         * <p>When output streaming is enabled, authentication and redirection cannot be handled automatically.
         * If output streaming is disabled, the {@link HttpURLConnection#setFixedLengthStreamingMode} and
         * {@link HttpURLConnection#setChunkedStreamingMode} methods of the underlying connection will never
         * be called.
         * @param outputStreaming if output streaming is enabled
         */
        public void setOutputStreaming(boolean outputStreaming) {
                this.outputStreaming = outputStreaming;
        }

        /**
         * Set the task executor for this request factory. Setting this property is required
         * for {@linkplain #createAsyncRequest(URI, HttpMethod) creating asynchronous requests}.
         * @param taskExecutor the task executor
         */
        public void setTaskExecutor(AsyncListenableTaskExecutor taskExecutor) {
                this.taskExecutor = taskExecutor;
        }


        @Override
        public ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod) throws IOException {
                HttpURLConnection connection = openConnection(uri.toURL(), this.proxy);
                prepareConnection(connection, httpMethod.name());

                if (this.bufferRequestBody) {
                        return new SimpleBufferingClientHttpRequest(connection, this.outputStreaming);
                }
                else {
                        return new SimpleStreamingClientHttpRequest(connection, this.chunkSize, this.outputStreaming);
                }
        }

        /**
         * {@inheritDoc}
         * <p>Setting the {@link #setTaskExecutor taskExecutor} property is required before calling this method.
         */
        @Override
        public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {
                Assert.state(this.taskExecutor != null, "Asynchronous execution requires TaskExecutor to be set");

                HttpURLConnection connection = openConnection(uri.toURL(), this.proxy);
                prepareConnection(connection, httpMethod.name());

                if (this.bufferRequestBody) {
                        return new SimpleBufferingAsyncClientHttpRequest(
                                        connection, this.outputStreaming, this.taskExecutor);
                }
                else {
                        return new SimpleStreamingAsyncClientHttpRequest(
                                        connection, this.chunkSize, this.outputStreaming, this.taskExecutor);
                }
        }

        /**
         * 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, @Nullable Proxy proxy) throws IOException {
                URLConnection urlConnection = (proxy != null ? url.openConnection(proxy) : url.openConnection());
                if (!HttpURLConnection.class.isInstance(urlConnection)) {
                        throw new IllegalStateException("HttpURLConnection required for [" + url + "] but got: " + 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 {
                if (this.connectTimeout >= 0) {
                        connection.setConnectTimeout(this.connectTimeout);
                }
                if (this.readTimeout >= 0) {
                        connection.setReadTimeout(this.readTimeout);
                }

                connection.setDoInput(true);

                if ("GET".equals(httpMethod)) {
                        connection.setInstanceFollowRedirects(true);
                }
                else {
                        connection.setInstanceFollowRedirects(false);
                }

                if ("POST".equals(httpMethod) || "PUT".equals(httpMethod) ||
                                "PATCH".equals(httpMethod) || "DELETE".equals(httpMethod)) {
                        connection.setDoOutput(true);
                }
                else {
                        connection.setDoOutput(false);
                }

                connection.setRequestMethod(httpMethod);
        }

}