/*

 * Copyright (c) 2015, 2018, 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 java.net.http;

import java.io.FileNotFoundException;

import java.io.InputStream;

import java.net.URI;

import java.net.URLPermission;

import java.nio.ByteBuffer;

import java.nio.charset.Charset;

import java.nio.charset.StandardCharsets;

import java.nio.file.Files;

import java.nio.file.Path;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.time.Duration;

import java.util.Iterator;

import java.util.Objects;

import java.util.Optional;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.Executor;

import java.util.concurrent.Flow;

import java.util.function.Supplier;

import java.net.http.HttpResponse.BodyHandler;

import jdk.internal.net.http.HttpRequestBuilderImpl;

import jdk.internal.net.http.RequestPublishers;

import static java.nio.charset.StandardCharsets.UTF_8;

/**

 * An HTTP request.

 *

 * <p> An {@code HttpRequest} instance is built through an {@code HttpRequest}

 * {@linkplain HttpRequest.Builder builder}. An {@code HttpRequest} builder

 * is obtained from one of the {@link HttpRequest#newBuilder(URI) newBuilder}

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

 * bodies are provided through a {@link BodyPublisher BodyPublisher} supplied

 * to one of the {@link Builder#DELETE(BodyPublisher) DELETE},

 * {@link Builder#POST(BodyPublisher) POST} or

 * {@link Builder#PUT(BodyPublisher) PUT} methods.

 * Once all required parameters have been set in the builder, {@link

 * Builder#build() build} will return the {@code HttpRequest}. Builders can be

 * copied and modified many times in order to build multiple related requests

 * that differ in some parameters.

 *

 * <p> The following is an example of a GET request that prints the response

 * body as a String:

 *

 * <pre>{@code    HttpClient client = HttpClient.newHttpClient();

 *   HttpRequest request = HttpRequest.newBuilder()

 *         .uri(URI.create("http://foo.com/"))

 *         .build();

 *   client.sendAsync(request, BodyHandlers.ofString())

 *         .thenApply(HttpResponse::body)

 *         .thenAccept(System.out::println)

 *         .join(); }</pre>

 *

 * <p>The class {@link BodyPublishers BodyPublishers} provides implementations

 * of many common publishers. Alternatively, a custom {@code BodyPublisher}

 * implementation can be used.

 *

 * @since 11

 */

public abstract class HttpRequest {

    /**

     * Creates an HttpRequest.

     */

    protected HttpRequest() {}

    /**

     * A builder of {@linkplain HttpRequest HTTP requests}.

     *

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

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

     *

     * <p> Each of the setter methods modifies the state of the builder

     * and returns the same instance. The methods are not synchronized and

     * should not be called from multiple threads without external

     * synchronization. The {@link #build() build} method returns a new

     * {@code HttpRequest} each time it is invoked. Once built an {@code

     * HttpRequest} is immutable, and can be sent multiple times.

     *

     * <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 may be managed by

     * specific APIs rather than through directly user set headers.

     *

     * @since 11

     */

    public interface Builder {

        /**

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

         *

         * @param uri the request URI

         * @return this builder

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

         *         supported

         */

        public Builder uri(URI uri);

        /**

         * Requests the server to acknowledge the request before sending the

         * 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 publisher 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 builder

         */

        public Builder expectContinue(boolean enable);

        /**

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

         *

         * <p> The corresponding {@link HttpResponse} should be checked for the

         * version that was actually 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 builder

         */

        public Builder version(HttpClient.Version version);

        /**

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

         * The given value is added to the list of values for that name.

         *

         * @implNote An implementation may choose to restrict some header names

         *           or values, as the HTTP Client may determine their value itself.

         *           For example, "Content-Length", which will be determined by

         *           the request Publisher. In such a case, an implementation of

         *           {@code HttpRequest.Builder} may choose to throw an

         *           {@code IllegalArgumentException} if such a header is passed

         *           to the builder.

         *

         * @param name the header name

         * @param value the header value

         * @return this builder

         * @throws IllegalArgumentException if the header name or value is not

         *         valid, see <a href="https://tools.ietf.org/html/rfc7230#section-3.2">

         *         RFC 7230 section-3.2</a>, or the header name or value is restricted

         *         by the implementation.

         */

        public Builder header(String name, String value);

        /**

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

         * request. The supplied {@code String} instances must alternate as

         * header names and header values.

         * To add several values to the same name then the same name must

         * be supplied with each new value.

         *

         * @param headers the list of name value pairs

         * @return this builder

         * @throws IllegalArgumentException if there are an odd number of

         *         parameters, or if a header name or value is not valid, see

         *         <a href="https://tools.ietf.org/html/rfc7230#section-3.2">

         *         RFC 7230 section-3.2</a>, or a header name or value is

         *         {@linkplain #header(String, String) restricted} by the

         *         implementation.

         */

        public Builder headers(String... headers);

        /**

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

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

         * thrown from {@link HttpClient#send(java.net.http.HttpRequest,

         * java.net.http.HttpResponse.BodyHandler) HttpClient::send} or

         * {@link HttpClient#sendAsync(java.net.http.HttpRequest,

         * java.net.http.HttpResponse.BodyHandler) HttpClient::sendAsync}

         * completes exceptionally with an {@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 builder

         * @throws IllegalArgumentException if the duration is non-positive

         */

        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 builder

         * @throws IllegalArgumentException if the header name or value is not valid,

         *         see <a href="https://tools.ietf.org/html/rfc7230#section-3.2">

         *         RFC 7230 section-3.2</a>, or the header name or value is

         *         {@linkplain #header(String, String) restricted} by the

         *         implementation.

         */

        public Builder setHeader(String name, String value);

        /**

         * Sets the request method of this builder to GET.

         * This is the default.

         *

         * @return this builder

         */

        public Builder GET();

        /**

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

         * request body publisher to the given value.

         *

         * @param bodyPublisher the body publisher

         *

         * @return this builder

         */

        public Builder POST(BodyPublisher bodyPublisher);

        /**

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

         * request body publisher to the given value.

         *

         * @param bodyPublisher the body publisher

         *

         * @return this builder

         */

        public Builder PUT(BodyPublisher bodyPublisher);

        /**

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

         * request body publisher to the given value.

         *

         * @param bodyPublisher the body publisher

         *

         * @return this builder

         */

        public Builder DELETE(BodyPublisher bodyPublisher);

        /**

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

         * given values.

         *

         * @apiNote The {@link BodyPublishers#noBody() noBody} request

         * body publisher can be used where no request body is required or

         * appropriate. Whether a method is restricted, or not, is

         * implementation specific. For example, some implementations may choose

         * to restrict the {@code CONNECT} method.

         *

         * @param method the method to use

         * @param bodyPublisher the body publisher

         * @return this builder

         * @throws IllegalArgumentException if the method is restricted

         */

        public Builder method(String method, BodyPublisher bodyPublisher);

        /**

         * Builds and returns an {@link HttpRequest}.

         *

         * @return a new {@code HttpRequest}

         * @throws IllegalStateException if a URI has not been set

         */

        public 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 Builder copy();

    }

    /**

     * Creates an {@code HttpRequest} builder with the given URI.

     *

     * @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 an {@code HttpRequest} builder.

     *

     * @return a new request builder

     */

    public static HttpRequest.Builder newBuilder() {

        return new HttpRequestBuilderImpl();

    }

    /**

     * Returns an {@code Optional} containing the {@link BodyPublisher} set on

     * this request. If no {@code BodyPublisher} was set in the requests's

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

     *

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

     */

    public abstract Optional<BodyPublisher> bodyPublisher();

    /**

     * 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 an {@code Optional} containing this request's timeout duration.

     * If the timeout duration was not set in the request's builder, then the

     * {@code Optional} is empty.

     *

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

     */

    public abstract Optional<Duration> timeout();

    /**

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

     * expect continue} setting.

     *

     * @return this request's expect continue setting

     */

    public abstract boolean expectContinue();

    /**

     * Returns this request's {@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();

    /**

     * Tests this HTTP request instance for equality with the given object.

     *

     * <p> If the given object is not an {@code HttpRequest} then this

     * method returns {@code false}. Two HTTP requests are equal if their URI,

     * method, and headers fields are all equal.

     *

     * <p> This method satisfies the general contract of the {@link

     * Object#equals(Object) Object.equals} method.

     *

     * @param obj the object to which this object is to be compared

     * @return {@code true} if, and only if, the given object is an {@code

     *         HttpRequest} that is equal to this HTTP request

     */

    @Override

    public final boolean equals(Object obj) {

       if (! (obj instanceof HttpRequest))

           return false;

       HttpRequest that = (HttpRequest)obj;

       if (!that.method().equals(this.method()))

           return false;

       if (!that.uri().equals(this.uri()))

           return false;

       if (!that.headers().equals(this.headers()))

           return false;

       return true;

    }

    /**

     * Computes a hash code for this HTTP request instance.

     *

     * <p> The hash code is based upon the HTTP request's URI, method, and

     * header components, and satisfies the general contract of the

     * {@link Object#hashCode Object.hashCode} method.

     *

     * @return the hash-code value for this HTTP request

     */

    public final int hashCode() {

        return method().hashCode()

                + uri().hashCode()

                + headers().hashCode();

    }

    /**

     * A {@code BodyPublisher} converts high-level Java objects into a flow of

     * byte buffers suitable for sending as a request body.  The class

     * {@link BodyPublishers BodyPublishers} provides implementations of many

     * common publishers.

     *

     * <p> The {@code BodyPublisher} interface extends {@link Flow.Publisher

     * Flow.Publisher<ByteBuffer>}, which means that a {@code BodyPublisher}

     * acts as a publisher of {@linkplain ByteBuffer byte buffers}.

     *

     * <p> When sending a request that contains a body, the HTTP Client

     * subscribes to the request's {@code BodyPublisher} in order to receive the

     * flow of outgoing request body data. The normal semantics of {@link

     * Flow.Subscriber} and {@link Flow.Publisher} are implemented by the HTTP

     * Client and are expected from {@code BodyPublisher} implementations. Each

     * outgoing request results in one HTTP Client {@code Subscriber}

     * subscribing to the {@code BodyPublisher} in order to provide the sequence

     * of byte buffers containing the request body. Instances of {@code

     * ByteBuffer} published by the publisher must be allocated by the

     * publisher, and must not be accessed after being published to the HTTP

     * Client. These subscriptions complete normally when the request body is

     * fully sent, and can be canceled or terminated early through error. If a

     * request needs to be resent for any reason, then a new subscription is

     * created which is expected to generate the same data as before.

     *

     * <p> A {@code BodyPublisher} that reports a {@linkplain #contentLength()

     * content length} of {@code 0} may not be subscribed to by the HTTP Client,

     * as it has effectively no data to publish.

     *

     * @see BodyPublishers

     * @since 11

     */

    public interface BodyPublisher extends Flow.Publisher<ByteBuffer> {

        /**

         * Returns the content length for this request body. May be zero

         * if no request body being sent, greater than zero for a fixed

         * length content, or less than zero for an unknown content length.

         *

         * <p> This method may be invoked before the publisher is subscribed to.

         * This method may be invoked more than once by the HTTP client

         * implementation, and MUST return the same constant value each time.

         *

         * @return the content length for this request body, if known

         */

        long contentLength();

    }

    /**

     * Implementations of {@link BodyPublisher BodyPublisher} that implement

     * various useful publishers, such as publishing the request body from a

     *

     * <p> The following are examples of using the predefined body publishers to

     * convert common high-level Java objects into a flow of data suitable for

     * sending as a request body:

     *

     *  <pre>{@code    // Request body from a String

     *   HttpRequest request = HttpRequest.newBuilder()

     *        .uri(URI.create("https://foo.com/"))

     *        .header("Content-Type", "text/plain; charset=UTF-8")

     *        .POST(BodyPublishers.ofString("some body text"))

     *        .build();

     *

     *   // Request body from a File

     *   HttpRequest request = HttpRequest.newBuilder()

     *        .uri(URI.create("https://foo.com/"))

     *        .header("Content-Type", "application/json")

     *        .POST(BodyPublishers.ofFile(Paths.get("file.json")))

     *        .build();

     *

     *   // Request body from a byte array

     *   HttpRequest request = HttpRequest.newBuilder()

     *        .uri(URI.create("https://foo.com/"))

     *        .POST(BodyPublishers.ofByteArray(new byte[] { ... }))

     *        .build(); }</pre>