/*
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * 
 *      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.eclipse.webdav;

import java.io.IOException;
import java.io.InputStream;
import org.w3c.dom.Document;

/**
 * Represents a response from a WebDAV server.
 * <p>
 * A response contains an open input stream, which is obtained
 * by <code>getInputStream()</code>.</p>
 * <p>
 * The client (i.e., the party that invoked the <code>Server</code>
 * method) is responsible for indicating that they're done with
 * the response object by calling its <code>close()</code> method;
 * this discards any remaining unread bytes, closes the stream,
 * and frees up any associated OS resources.</p>
 * <p>
 * Failing to close the response may lead to spurious bytes being
 * left on the response socket and causing unspecified behavior on
 * subsequent request/response interactions.</p>
 * <p>
 * The recommended basic usage pattern is as follows:
 * <pre>
 * Response r = server.mkcol(source, context);
 * try {
 *   if (r.getStatus() == Response.SC_OK) {
 *     ... // handle standard response
 *   } else {
 *     ... // handle non-standard response
 *   }
 * } finally {
 *     r.close();
 * }
 * </pre>
 * Certain kinds of responses (e.g., certain status codes,
 * responses to certain methods) contain a WebDAV-specified
 * XML element in the response body. The presence (or expected
 * presence) of an XML element body is indicated by 
 * <code>hasDocumentBody</code> returning <code>true</code>,
 * in which case the client should access this element with
 * <code>readDocumentBody()</code>; in other cases, 
 * <code>hasDocumentBody</code> returns<code>false</code>,
 * and the client should access the stream of raw bytes with
 * <code>getInputStream()</code>.
 * <p>
 * <b>Note:</b> This class/interface is part of an interim API that is still under 
 * development and expected to change significantly before reaching stability. 
 * It is being made available at this early stage to solicit feedback from pioneering 
 * adopters on the understanding that any code that uses this API will almost 
 * certainly be broken (repeatedly) as the API evolves.
 * </p>
 */
public interface IResponse {

    /*
     * HTTP/1.1 status codes; see RFC 1945 and the WebDAV specification (RFC 2518).
     */

    /**
     * Status code (100) indicating the client may continue with
     * its request.  This interim response is used to inform the
     * client that the initial part of the request has been
     * received and has not yet been rejected by the server.
     */
    public final int SC_CONTINUE = 100;

    /**
     * Status code (101) indicating the server is switching protocols
     * according to Upgrade header.
     */
    public final int SC_SWITCHING_PROTOCOLS = 101;

    /**
     * Status code (102) indicating the server is still processing the request.
     */
    public final int SC_PROCESSING = 102;

    // Request was successfully received, understood, and accepted.

    /**
     * Status code (200) indicating the request succeeded normally.
     */
    public final int SC_OK = 200;

    /**
     * Status code (201) indicating the request succeeded and created
     * a new resource on the server.
     */
    public final int SC_CREATED = 201;

    /**
     * Status code (202) indicating that a request was accepted for
     * processing, but was not completed.
     */
    public final int SC_ACCEPTED = 202;

    /**
     * Status code (203) indicating that the meta information presented
     * by the client did not originate from the server.
     */
    public final int SC_NON_AUTHORITATIVE_INFORMATION = 203;

    /**
     * Status code (204) indicating that the request succeeded but that
     * there was no new information to return.
     */
    public final int SC_NO_CONTENT = 204;

    /**
     * Status code (205) indicating that the agent SHOULD reset the document
     * view which caused the request to be sent.
     */
    public final int SC_RESET_CONTENT = 205;

    /**
     * Status code (206) indicating that the server has fulfilled the partial
     * GET request for the resource.
     */
    public final int SC_PARTIAL_CONTENT = 206;

    /**
     * Status code (207) indicating that the response provides status for multiple
     * independent operations.
     */
    public final int SC_MULTI_STATUS = 207;

    // Redirection: indicates further action needs to be taken by the user.

    /** Status code (300) indicating that the requested resource corresponds to any one of
     * a set of representations, each with its own specific location
     */
    public final int SC_MULTIPLE_CHOICES = 300;

    /**
     * Status code (301) indicating that the resource has permanently
     * moved to a new location, and that future references should use a
     * new URI with their requests.
     */
    public final int SC_MOVED_PERMANENTLY = 301;

    /**
     * Status code (302) indicating that the resource has temporarily
     * moved to another location, but that future references should
     * still use the original URI to access the resource.
     */
    public final int SC_MOVED_TEMPORARILY = 302;

    /**
     * Status code (303) indicating that the response to the request can
     * be found under a different URI.
     */
    public final int SC_SEE_OTHER = 303;

    /**
     * Status code (304) indicating that a conditional GET operation
     * found that the resource was available and not modified.
     */
    public final int SC_NOT_MODIFIED = 304;

    /**
     * Status code (305) indicating that the requested resource MUST be accessed
     * through the proxy given by the Location field.
     */
    public final int SC_USE_PROXY = 305;

    // Client error

    /**
     * Status code (400) indicating the request sent by the client was
     * syntactically incorrect.
     */
    public final int SC_BAD_REQUEST = 400;

    /**
     * Status code (401) indicating that the request requires HTTP
     * authentication.
     */
    public final int SC_UNAUTHORIZED = 401;

    /**
     * Status code (402) reserved for future use.
     */
    public final int SC_PAYMENT_REQUIRED = 402;

    /**
     * Status code (403) indicating the server understood the request
     * but refused to fulfill it.
     */
    public final int SC_FORBIDDEN = 403;

    /**
     * Status code (404) indicating that the requested resource is not
     * available.
     */
    public final int SC_NOT_FOUND = 404;

    /**
     * Status code (405) indicating the method specified is not
     * allowed for the resource.
     */
    public final int SC_METHOD_NOT_ALLOWED = 405;

    /**
     * Status code (406) indicating the resource identified by the
     * request is only capable of generating response entities
     * which have content characteristics not acceptable according
     * to the accept headerssent in the request.
     */
    public final int SC_NOT_ACCEPTABLE = 406;

    /**
     * Status code (407) indicating the client MUST first authenticate
     * itself with the proxy.
     */
    public final int SC_PROXY_AUTHENTICATION_REQUIRED = 407;

    /**
     * Status code (408) indicating the client did not produce a request within
     * the time that the server was prepared to wait.
     */
    public final int SC_REQUEST_TIMEOUT = 408;

    /**
     * Status code (409) indicating that the request could not be
     * completed due to a conflict with the current state of the
     * resource.
     */
    public final int SC_CONFLICT = 409;

    /**
     * Status code (410) indicating the server did not receive a timely
     * response from the upstream server while acting as a gateway or proxy.
     */
    public final int SC_GONE = 410;

    /**
     * Status code (411) indicating the request cannot be handled
     * without a defined Content-Length.
     */
    public final int SC_LENGTH_REQUIRED = 411;

    /**
     * Status code (412) indicating the precondition given in one
     * or more of the request-header fields evaluated to false
     * when it was tested on the server.
     */
    public final int SC_PRECONDITION_FAILED = 412;

    /**
     * Status code (413) indicating the server is refusing to
     * process a request because the request entity is larger
     * than the server is willing or able to process.
     */
    public final int SC_REQUEST_TOO_LONG = 413;

    /**
     * Status code (414) indicating the server is refusing to
     * service the request because the Request-URI is longer
     * than the server is willing to interpret.
     */
    public final int SC_REQUEST_URI_TOO_LONG = 414;

    /**
     * Status code (415) indicating the server is refusing to service
     * the request because the entity of the request is in a format
     * not supported by the requested resource for the requested
     * method.
     */
    public final int SC_UNSUPPORTED_MEDIA_TYPE = 415;

    /**
     * Status code (422) indicating the server understands the content type of the
     * request entity, but was unable to process the contained instructions.
     */
    public final int SC_UNPROCESSABLE_ENTITY = 422;

    /**
     * Status code (423) indicating the source or destination resource of a
     * method is locked.
     */
    public final int SC_LOCKED = 423;

    /**
     * Status code (424) indicating the method was not executed on
     * a particular resource within its scope because some part of
     * the method's execution failed causing the entire method to be
     * aborted.
     */
    public final int SC_FAILED_DEPENDENCY = 424;

    /**
     * Status code (425) indicating that the resource does not have sufficient
     * space to record the state of the resource after the execution of the method.
     */
    public final int SC_INSUFFICIENT_SPACE_ON_RESOURCE = 425;

    // Server errors

    /**
     * Status code (500) indicating an error inside the HTTP service
     * which prevented it from fulfilling the request.
     */
    public final int SC_INTERNAL_SERVER_ERROR = 500;

    /**
     * Status code (501) indicating the HTTP service does not support
     * the functionality needed to fulfill the request.
     */
    public final int SC_NOT_IMPLEMENTED = 501;

    /**
     * Status code (502) indicating that the HTTP server received an
     * invalid response from a server it consulted when acting as a
     * proxy or gateway.
     */
    public final int SC_BAD_GATEWAY = 502;

    /**
     * Status code (503) indicating that the HTTP service is
     * temporarily overloaded, and unable to handle the request.
     */
    public final int SC_SERVICE_UNAVAILABLE = 503;

    /**
     * Status code (504) indicating the server did not receive a
     * timely response from the upstream server while acting as a
     * gateway or proxy.
     */
    public final int SC_GATEWAY_TIMEOUT = 504;

    /**
     * Status code (505) indicating the server does not support or
     * refuses to support the HTTP protocol version that was used
     * in the request message.
     */
    public final int SC_HTTP_VERSION_NOT_SUPPORTED = 505;

    /**
     * Status code (506) indicating the server terminated an operation
     * because it encountered an infinite loop while processing a request
     * with "Depth: infinity".
     */
    public final int SC_LOOP_DETECTED = 506;

    /**
     * Status code (507) indicating the server is unable to create the
     * requested binding because it would bind a segment in a collection
     * on one server to a resource on a different server.
     */
    public final int SC_CROSS_SERVER_BINDING_FORBIDDEN = 507;

    /**
     * Closes this response. Any unread bytes that make up
     * the body of this response are discarded; any underlying
     * OS resources associated with this response are freed.
     * <p>
     * This method should be invoked on every response returned
     * from the server <b>without exception</b>.</p>
     *
     * @exception IOException if there was a problem closing this
     *  response
     */
    public void close() throws IOException;

    /**
     * Returns this response's header fields.
     *
     * @return the <code>Context</code> containing the header
     * key, value pairs.
     */
    public IContext getContext();

    /**
     * Gets the contents of the response body as a DOM
     * <code>Document</code>.
     * <p>
     * This response MUST have an XML body (i.e., <code>
     * hasDocumentBody()</code> must return <code>true</code>).</p>
     * <p>
     * Once the body has been read as an <code>InputStream</code>
     * it cannot be subsequently read as a <code>Document</code>
     * (the bytes have been consumed).
     * <p>
     * If a problem occurs parsing the document body an <code>
     * IOException</code> is thrown.
     *
     * @return DOM document obtained from the XML body.
     * @exception IOException if there was a problem receiving the
     * response or interpreting it as XML.
     */
    public Document getDocumentBody() throws IOException;

    /**
     * Returns an open input stream for reading the
     * the body of this response.
     * <p>
     * This response must not have an XML body (i.e.,
     * <code>hasElementBody()</code> must return <code>false
     * </code>).</p>
     * <p>
     * The client may close the stream early, however, the
     * resulting stream will be closed if necessary when
     * the client closes this response.</p>
     *
     * @return the bytes of the response as an <code>InputStream</code>.
     */
    public InputStream getInputStream();

    /**
     * Returns the HTTP response status code.
     * <p>
     * As a convenience, the status code should be
     * one of the <code>SC_* </code> constants
     * defined in this class.</p>
     *
     * @return the response status code.
     */
    public int getStatusCode();

    /**
     * Returns the response status message.
     * <p>
     * The status message is the HTTP string that follows
     * the status code on the first line of the response.</p>
     *
     * @return the status message verbatim.
     */
    public String getStatusMessage();

    /**
     * Returns whether this response has an XML element
     * as a body; this is the element that would be read
     * if <code>readDocumentBody()</code> was called.
     * <p>
     * This method can be called numerous times, and can
     * be called after the body has been read either as
     * an InputStream or a Document -- all with no bad
     * effect.</p>
     *
     * @return <code>true</code> if this message has a
     *    document body and <code>false</code> otherwise.
     */
    public boolean hasDocumentBody();
}
