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 * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.incubator.http;

import java.io.FileNotFoundException;

import java.io.InputStream;

import java.net.URI;

import java.nio.ByteBuffer;

import java.nio.charset.*;

import java.nio.file.Path;

import java.time.Duration;

import java.util.Iterator;

import java.util.Optional;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.Flow;

import java.util.function.Supplier;

/**

 * Represents one HTTP request which can be sent to a server.

 * {@Incubating }

 *

 * <p> {@code HttpRequest}s are built from {@code HttpRequest}

 * {@link HttpRequest.Builder builder}s. {@code HttpRequest} builders are

 * obtained by calling {@link HttpRequest#newBuilder(java.net.URI)

 * HttpRequest.newBuilder}.

 * A request's {@link java.net.URI}, headers and body can be set. Request bodies

 * are provided through a {@link BodyProcessor} object supplied to the

 * {@link Builder#DELETE(jdk.incubator.http.HttpRequest.BodyProcessor) DELETE},

 * {@link Builder#POST(jdk.incubator.http.HttpRequest.BodyProcessor) POST} or

 * {@link Builder#PUT(jdk.incubator.http.HttpRequest.BodyProcessor) PUT} methods.

 * {@link Builder#GET() GET} does not take a body. Once all required

 * parameters have been set in the builder, {@link Builder#build() } is called

 * to return the {@code HttpRequest}. Builders can also be copied

 * and modified multiple times in order to build multiple related requests that

 * differ in some parameters.

 *

 * <p> Two simple, example HTTP interactions are shown below:

 * <pre>

 * {@code

 *      HttpClient client = HttpClient.newHttpClient();

 *

 *      // GET

 *      HttpResponse<String> response = client.send(

 *          HttpRequest

 *              .newBuilder(new URI("http://www.foo.com/"))

 *              .headers("Foo", "foovalue", "Bar", "barvalue")

 *              .GET()

 *              .build(),

 *          BodyHandler.asString()

 *      );

 *      int statusCode = response.statusCode();

 *      String body = response.body();

 *

 *      // POST

 *      HttpResponse<Path> response = client.send(

 *          HttpRequest

 *              .newBuilder(new URI("http://www.foo.com/"))

 *              .headers("Foo", "foovalue", "Bar", "barvalue")

 *              .POST(BodyProcessor.fromString("Hello world"))

 *              .build(),

 *          BodyHandler.asFile(Paths.get("/path"))

 *      );

 *      int statusCode = response.statusCode();

 *      Path body = response.body(); // should be "/path"

 * }

 * </pre>

 * <p> The request is sent and the response obtained by calling one of the

 * following methods in {@link HttpClient}.

 * <ul><li>{@link HttpClient#send(HttpRequest, HttpResponse.BodyHandler)} blocks

 * until the entire request has been sent and the response has been received.</li>

 * <li>{@link HttpClient#sendAsync(HttpRequest,HttpResponse.BodyHandler)} sends the

 * request and receives the response asynchronously. Returns immediately with a

 * {@link java.util.concurrent.CompletableFuture CompletableFuture}<{@link

 * HttpResponse}&gt;.</li>

 * <li>{@link HttpClient#sendAsync(HttpRequest,HttpResponse.MultiProcessor) }

 * sends the request asynchronously, expecting multiple responses. This

 * capability is of most relevance to HTTP/2 server push, but can be used for

 * single responses (HTTP/1.1 or HTTP/2) also.</li>

 * </ul>

 *

 * <p> Once a {@link HttpResponse} is received, the headers, response code

 * and body (typically) are available. Whether the body has been read or not

 * depends on the type {@code <T>} of the response body. See below.

 *

 * <p> See below for discussion of synchronous versus asynchronous usage.

 *

 * <p> <b>Request bodies</b>

 *

 * <p> Request bodies are sent using one of the request processor implementations

 * below provided in {@link HttpRequest.BodyProcessor}, or else a custom implementation can be

 * used.

 * <ul>

 * <li>{@link BodyProcessor#fromByteArray(byte[]) fromByteArray(byte[])} from byte array</li>

 * <li>{@link BodyProcessor#fromByteArrays(Iterable) fromByteArrays(Iterable)}

 *      from an Iterable of byte arrays</li>

 * <li>{@link BodyProcessor#fromFile(java.nio.file.Path) fromFile(Path)} from the file located

 *     at the given Path</li>

 * <li>{@link BodyProcessor#fromString(java.lang.String) fromString(String)} from a String </li>

 * <li>{@link BodyProcessor#fromInputStream(Supplier) fromInputStream}({@link Supplier}&lt;

 *      {@link InputStream}&gt;) from an InputStream obtained from a Supplier</li>

 * <li>{@link BodyProcessor#noBody() } no request body is sent</li>

 * </ul>

 *

 * <p> <b>Response bodies</b>

 *

 * <p>Responses bodies are handled at two levels. When sending the request,

 * a response body handler is specified. This is a function ({@link HttpResponse.BodyHandler})

 * which will be called with the response status code and headers, once these are received. This

 * function is then expected to return a {@link HttpResponse.BodyProcessor}

 * {@code <T>} which is then used to read the response body converting it

 * into an instance of T. After this occurs, the response becomes

 * available in a {@link HttpResponse} and {@link HttpResponse#body()} can then

 * be called to obtain the body. Some implementations and examples of usage of both {@link

 * HttpResponse.BodyProcessor} and {@link HttpResponse.BodyHandler}

 * are provided in {@link HttpResponse}:

 * <p><b>Some of the pre-defined body handlers</b><br>

 * <ul>

 * <li>{@link HttpResponse.BodyHandler#asByteArray() BodyHandler.asByteArray()}

 * stores the body in a byte array</li>

 * <li>{@link HttpResponse.BodyHandler#asString() BodyHandler.asString()}

 * stores the body as a String </li>

 * <li>{@link HttpResponse.BodyHandler#asFile(java.nio.file.Path)

 * BodyHandler.asFile(Path)} stores the body in a named file</li>

 * <li>{@link HttpResponse.BodyHandler#discard(Object) BodyHandler.discard()}

 * discards the response body and returns the given value instead.</li>

 * </ul>

 *

 * <p> <b>Multi responses</b>

 *

 * <p> With HTTP/2 it is possible for a server to return a main response and zero

 * or more additional responses (known as server pushes) to a client-initiated

 * request. These are handled using a special response processor called {@link

 * HttpResponse.MultiProcessor}.

 *

 * <p> <b>Blocking/asynchronous behavior and thread usage</b>

 *

 * <p> There are two styles of request sending: <i>synchronous</i> and

 * <i>asynchronous</i>. {@link HttpClient#send(HttpRequest, HttpResponse.BodyHandler) }

 * blocks the calling thread until the request has been sent and the response received.

 *

 * <p> {@link HttpClient#sendAsync(HttpRequest, HttpResponse.BodyHandler)}  is asynchronous and returns

 * immediately with a {@link java.util.concurrent.CompletableFuture}<{@link

 * HttpResponse}> and when this object completes (in a background thread) the

 * response has been received.

 *

 * <p> {@link HttpClient#sendAsync(HttpRequest,HttpResponse.MultiProcessor)}

 * is the variant for multi responses and is also asynchronous.

 *

 * <p> {@code CompletableFuture}s can be combined in different ways to declare the

 * dependencies among several asynchronous tasks, while allowing for the maximum

 * level of parallelism to be utilized.

 *

 * <p> <b>Security checks</b>

 *

 * <p> If a security manager is present then security checks are performed by

 * the sending methods. A {@link java.net.URLPermission} or {@link java.net.SocketPermission} is required to

 * access any destination origin server and proxy server utilised. {@code URLPermission}s

 * should be preferred in policy files over {@code SocketPermission}s given the more

 * limited scope of {@code URLPermission}. Permission is always implicitly granted to a

 * system's default proxies. The {@code URLPermission} form used to access proxies uses

 * a method parameter of {@code "CONNECT"} (for all kinds of proxying) and a url string

 * of the form {@code "socket://host:port"} where host and port specify the proxy's

 * address.

 *

 * <p> <b>Examples</b>

 * <pre>{@code

 *      HttpClient client = HttpClient

 *              .newBuilder()

 *              .build();

 *

 *      HttpRequest request = HttpRequest

 *              .newBuilder(new URI("http://www.foo.com/"))

 *              .POST(BodyProcessor.fromString("Hello world"))

 *              .build();

 *

 *      HttpResponse<Path> response =

 *          client.send(request, BodyHandler.asFile(Paths.get("/path")));

 *

 *      Path body = response.body();

 * }</pre>

 *

 * <p><b>Asynchronous Example</b>

 *

 * <p> The above example will work asynchronously, if {@link HttpClient#sendAsync

 * (HttpRequest, HttpResponse.BodyHandler) sendAsync} is used instead of

 * {@link HttpClient#send(HttpRequest,HttpResponse.BodyHandler) send}

 * in which case the returned object is a {@link CompletableFuture}{@code <HttpResponse>}

 * instead of {@link HttpResponse}. The following example shows how multiple requests

 * can be sent asynchronously. It also shows how dependent asynchronous operations

 * (receiving response, and receiving response body) can be chained easily using

 * one of the many methods in {@code CompletableFuture}.

 * <pre>

 * {@code

 *  // fetch a list of target URIs asynchronously and store them in Files.

 *

 *      List<URI> targets = ...

 *

 *      List<CompletableFuture<File>> futures = targets

 *          .stream()

 *          .map(target -> client

 *                  .sendAsync(

 *                      HttpRequest.newBuilder(target)

 *                                 .GET()

 *                                 .build(),

 *                      BodyHandler.asFile(Paths.get("base", target.getPath())))

 *                  .thenApply(response -> response.body())

 *                  .thenApply(path -> path.toFile()))

 *          .collect(Collectors.toList());

 *

 *      // all async operations waited for here

 *

 *      CompletableFuture.allOf(futures.toArray(new CompletableFuture<?>[0]))

 *          .join();

 *

 *      // all elements of futures have completed and can be examined.

 *      // Use File.exists() to check whether file was successfully downloaded

 * }

 * </pre>

 * <p>

 * Unless otherwise stated, {@code null} parameter values will cause methods

 * of this class to throw {@code NullPointerException}.

 *

 * @since 9

 */

public abstract class HttpRequest {

    /**

     * Creates an HttpRequest.

     */

    protected HttpRequest() {}

    /**

     * A builder of {@link HttpRequest}s.

     * {@Incubating}

     *

     * <p> {@code HttpRequest.Builder}s are created by calling {@link

     * HttpRequest#newBuilder(URI)} or {@link HttpRequest#newBuilder()}.

     *

     * <p> Each of the setter methods in this class modifies the state of the

     * builder and returns <i>this</i> (ie. the same instance). The methods are

     * not synchronized and should not be called from multiple threads without

     * external synchronization.

     * <p>Note, that not all request headers may be set by user code. Some are

     * restricted for security reasons and others such as the headers relating

     * to authentication, redirection and cookie management are managed by

     * specific APIs rather than through directly user set headers.

     *

     * <p> The {@linkplain #build() build} method returns a new {@code

     * HttpRequest} each time it is invoked.

     *

     * @since 9

     */

    public abstract static class Builder {

        /**

         * Creates a Builder.

         */

        protected Builder() {}

        /**

         * Sets this {@code HttpRequest}'s request {@code URI}.

         *

         * @param uri the request URI

         * @return this request builder

         * @throws IllegalArgumentException if the {@code URI} scheme is not

         *         supported.

         */

        public abstract Builder uri(URI uri);

        /**

         * Request server to acknowledge request before sending request

         * body. This is disabled by default. If enabled, the server is requested

         * to send an error response or a {@code 100 Continue} response before the client

         * sends the request body. This means the request processor for the

         * request will not be invoked until this interim response is received.

         *

         * @param enable {@code true} if Expect continue to be sent

         * @return this request builder

         */

        public abstract Builder expectContinue(boolean enable);

        /**

         * Sets the preferred {@link HttpClient.Version} for this

         * request. The corresponding {@link HttpResponse} should be checked

         * for the version that was used. If the version is not set

         * in a request, then the version requested will be that of the

         * sending {@link HttpClient}.

         *

         * @param version the HTTP protocol version requested

         * @return this request builder

         */

        public abstract Builder version(HttpClient.Version version);

        /**

         * Adds the given name value pair to the set of headers for this request.

         *

         * @param name the header name

         * @param value the header value

         * @return this request builder

         */

        public abstract Builder header(String name, String value);

//        /**

//         * Overrides the {@code ProxySelector} set on the request's client for this

//         * request.

//         *

//         * @param proxy the ProxySelector to use

//         * @return this request builder

//         */

//        public abstract Builder proxy(ProxySelector proxy);

        /**

         * Adds the given name value pairs to the set of headers for this

         * request. The supplied {@code String}s must alternate as names and values.

         *

         * @param headers the list of String name value pairs

         * @return this request builder

         * @throws IllegalArgumentException if there is an odd number of

         *                                  parameters

         */

        // TODO (spec): consider signature change

        // public abstract Builder headers(java.util.Map.Entry<String,String>... headers);

        public abstract Builder headers(String... headers);

        /**

         * Sets a timeout for this request. If the response is not received

         * within the specified timeout then a {@link HttpTimeoutException} is

         * thrown from {@link HttpClient#send(jdk.incubator.http.HttpRequest,

         * jdk.incubator.http.HttpResponse.BodyHandler) HttpClient::send} or

         * {@link HttpClient#sendAsync(jdk.incubator.http.HttpRequest,

         * jdk.incubator.http.HttpResponse.BodyHandler) HttpClient::sendAsync}

         * completes exceptionally with a {@code HttpTimeoutException}. The effect

         * of not setting a timeout is the same as setting an infinite Duration, ie.

         * block forever.

         *

         * @param duration the timeout duration

         * @return this request builder

         */

        public abstract Builder timeout(Duration duration);

        /**

         * Sets the given name value pair to the set of headers for this

         * request. This overwrites any previously set values for name.

         *

         * @param name the header name

         * @param value the header value

         * @return this request builder

         */

        public abstract Builder setHeader(String name, String value);

        /**

         * Sets the request method of this builder to GET.

         *

         * @return a {@code HttpRequest}

         */

        public abstract Builder GET();

        /**

         * Sets the request method of this builder to POST and sets its

         * request body processor to the given value.

         *

         * @param body the body processor

         *

         * @return a {@code HttpRequest}

         */

        public abstract Builder POST(BodyProcessor body);

        /**

         * Sets the request method of this builder to PUT and sets its

         * request body processor to the given value.

         *

         * @param body the body processor

         *

         * @return a {@code HttpRequest}

         */

        public abstract Builder PUT(BodyProcessor body);

        /**

         * Sets the request method of this builder to DELETE and sets its

         * request body processor to the given value.

         *

         * @param body the body processor

         *

         * @return a {@code HttpRequest}

         */

        public abstract Builder DELETE(BodyProcessor body);

        /**

         * Sets the request method and request body of this builder to the

         * given values.

         *

         * @param body the body processor

         * @param method the method to use

         * @return a {@code HttpRequest}

         * @throws IllegalArgumentException if an unrecognized method is used

         */

        public abstract Builder method(String method, BodyProcessor body);

        /**

         * Builds and returns a {@link HttpRequest}.

         *

         * @return the request

         */

        public abstract HttpRequest build();

        /**

         * Returns an exact duplicate copy of this {@code Builder} based on current

         * state. The new builder can then be modified independently of this

         * builder.

         *

         * @return an exact copy of this Builder

         */

        public abstract Builder copy();

    }

    /**

     * Creates a {@code HttpRequest} builder.

     *

     * @param uri the request URI

     * @return a new request builder

     * @throws IllegalArgumentException if the URI scheme is not supported.

     */

    public static HttpRequest.Builder newBuilder(URI uri) {

        return new HttpRequestBuilderImpl(uri);

    }

    /**

     * Creates a {@code HttpRequest} builder.

     *

     * @return a new request builder

     */

    public static HttpRequest.Builder newBuilder() {

        return new HttpRequestBuilderImpl();

    }

    /**

     * Returns an {@code Optional} containing the {@link BodyProcessor}

     * set on this request. If no {@code BodyProcessor} was set in the

     * requests's builder, then the {@code Optional} is empty.

     *

     * @return an {@code Optional} containing this request's

     *         {@code BodyProcessor}

     */

    public abstract Optional<BodyProcessor> bodyProcessor();

    /**

     * Returns the request method for this request. If not set explicitly,

     * the default method for any request is "GET".

     *

     * @return this request's method

     */

    public abstract String method();

    /**

     * Returns the duration for this request.

     *

     * @return this requests duration

     */

    public abstract Duration duration();

    /**

     * Returns this request's {@link HttpRequest.Builder#expectContinue(boolean)

     * expect continue } setting.

     *

     * @return this request's expect continue setting

     */

    public abstract boolean expectContinue();

    /**

     * Returns this request's request {@code URI}.

     *

     * @return this request's URI

     */

    public abstract URI uri();

    /**

     * Returns an {@code Optional} containing the HTTP protocol version that

     * will be requested for this {@code HttpRequest}. If the version was not

     * set in the request's builder, then the {@code Optional} is empty.

     * In that case, the version requested will be that of the sending

     * {@link HttpClient}. The corresponding {@link HttpResponse} should be

     * queried to determine the version that was actually used.

     *

     * @return HTTP protocol version

     */

    public abstract Optional<HttpClient.Version> version();

    /**

     * The (user-accessible) request headers that this request was (or will be)

     * sent with.

     *

     * @return this request's HttpHeaders

     */

    public abstract HttpHeaders headers();

    /**

     * A request body handler which sends no request body.

     *

     * @return a BodyProcessor

     */

    public static BodyProcessor noBody() {