/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsIChannel.idl"

interface nsIHttpHeaderVisitor;

/**
 * nsIHttpChannel
 *
 * This interface allows for the modification of HTTP request parameters and
 * the inspection of the resulting HTTP response status and headers when they
 * become available.
 */
[scriptable, uuid(9277fe09-f0cc-4cd9-bbce-581dd94b0260)]
interface nsIHttpChannel : nsIChannel
{
    /**************************************************************************
     * REQUEST CONFIGURATION
     *
     * Modifying request parameters after asyncOpen has been called is an error.
     */

    /**
     * Set/get the HTTP request method (default is "GET").  Setter is case
     * insensitive; getter returns an uppercase string.
     *
     * This attribute may only be set before the channel is opened.
     *
     * NOTE: The data for a "POST" or "PUT" request can be configured via
     * nsIUploadChannel; however, after setting the upload data, it may be
     * necessary to set the request method explicitly.  The documentation
     * for nsIUploadChannel has further details.
     *
     * @throws NS_ERROR_IN_PROGRESS if set after the channel has been opened.
     */
    attribute ACString requestMethod;

    /**
     * Get/set the HTTP referrer URI.  This is the address (URI) of the
     * resource from which this channel's URI was obtained (see RFC2616 section
     * 14.36).
     * 
     * This attribute may only be set before the channel is opened.
     *
     * NOTE: The channel may silently refuse to set the Referer header if the
     * URI does not pass certain security checks (e.g., a "https://" URL will
     * never be sent as the referrer for a plaintext HTTP request).  The
     * implementation is not required to throw an exception when the referrer
     * URI is rejected.
     *
     * @throws NS_ERROR_IN_PROGRESS if set after the channel has been opened.
     */
    attribute nsIURI referrer;

    /**
     * Get the value of a particular request header.
     *
     * @param aHeader
     *        The case-insensitive name of the request header to query (e.g.,
     *        "Cache-Control").
     *
     * @return the value of the request header.
     * @throws NS_ERROR_NOT_AVAILABLE if the header is not set.
     */
    ACString getRequestHeader(in ACString aHeader);

    /**
     * Set the value of a particular request header.
     *
     * This method allows, for example, the cookies module to add "Cookie"
     * headers to the outgoing HTTP request.
     *
     * This method may only be called before the channel is opened.
     *
     * @param aHeader
     *        The case-insensitive name of the request header to set (e.g.,
     *        "Cookie").
     * @param aValue
     *        The request header value to set (e.g., "X=1").
     * @param aMerge
     *        If true, the new header value will be merged with any existing
     *        values for the specified header.  This flag is ignored if the
     *        specified header does not support merging (e.g., the "Content-
     *        Type" header can only have one value).  The list of headers for
     *        which this flag is ignored is an implementation detail.  If this
     *        flag is false, then the header value will be replaced with the
     *        contents of |aValue|.
     *
     * If aValue is empty and aMerge is false, the header will be cleared.
     *
     * @throws NS_ERROR_IN_PROGRESS if called after the channel has been
     *         opened.
     */
    void setRequestHeader(in ACString aHeader,
                          in ACString aValue,
                          in boolean aMerge);

    /**
     * Call this method to visit all request headers.  Calling setRequestHeader
     * while visiting request headers has undefined behavior.  Don't do it!
     *
     * @param aVisitor
     *        the header visitor instance.
     */
    void visitRequestHeaders(in nsIHttpHeaderVisitor aVisitor);

    /**
     * This attribute is a hint to the channel to indicate whether or not
     * the underlying HTTP transaction should be allowed to be pipelined
     * with other transactions.  This should be set to FALSE, for example,
     * if the application knows that the corresponding document is likely
     * to be very large.
     *
     * This attribute is true by default, though other factors may prevent
     * pipelining.
     *
     * This attribute may only be set before the channel is opened.
     *
     * @throws NS_ERROR_FAILURE if set after the channel has been opened.
     */
    attribute boolean allowPipelining;

    /**
     * This attribute specifies the number of redirects this channel is allowed
     * to make.  If zero, the channel will fail to redirect and will generate
     * a NS_ERROR_REDIRECT_LOOP failure status.
     *
     * NOTE: An HTTP redirect results in a new channel being created.  If the
     * new channel supports nsIHttpChannel, then it will be assigned a value
     * to its |redirectionLimit| attribute one less than the value of the
     * redirected channel's |redirectionLimit| attribute.  The initial value
     * for this attribute may be a configurable preference (depending on the
     * implementation).
     */
    attribute unsigned long redirectionLimit;


    /**************************************************************************
     * RESPONSE INFO
     *
     * Accessing response info before the onStartRequest event is an error.
     */

    /**
     * Get the HTTP response code (e.g., 200).
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    readonly attribute unsigned long responseStatus;

    /**
     * Get the HTTP response status text (e.g., "OK").
     *
     * NOTE: This returns the raw (possibly 8-bit) text from the server.  There
     * are no assumptions made about the charset of the returned text.  You
     * have been warned!
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    readonly attribute ACString responseStatusText;

    /**
     * Returns true if the HTTP response code indicates success.  The value of
     * nsIRequest::status will be NS_OK even when processing a 404 response
     * because a 404 response may include a message body that (in some cases)
     * should be shown to the user.
     *
     * Use this attribute to distinguish server error pages from normal pages,
     * instead of comparing the response status manually against the set of
     * valid response codes, if that is required by your application.
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    readonly attribute boolean requestSucceeded;

    /**
     * Get the value of a particular response header.
     *
     * @param aHeader
     *        The case-insensitive name of the response header to query (e.g.,
     *        "Set-Cookie").
     *
     * @return the value of the response header.
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest) or if the header is
     *         not set in the response.
     */
    ACString getResponseHeader(in ACString header);

    /**
     * Set the value of a particular response header.
     *
     * This method allows, for example, the HTML content sink to inform the HTTP
     * channel about HTTP-EQUIV headers found in HTML <META> tags.
     *
     * @param aHeader
     *        The case-insensitive name of the response header to set (e.g.,
     *        "Cache-control").
     * @param aValue
     *        The response header value to set (e.g., "no-cache").
     * @param aMerge
     *        If true, the new header value will be merged with any existing
     *        values for the specified header.  This flag is ignored if the
     *        specified header does not support merging (e.g., the "Content-
     *        Type" header can only have one value).  The list of headers for
     *        which this flag is ignored is an implementation detail.  If this
     *        flag is false, then the header value will be replaced with the
     *        contents of |aValue|.
     *
     * If aValue is empty and aMerge is false, the header will be cleared.
     * 
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     * @throws NS_ERROR_ILLEGAL_VALUE if changing the value of this response
     *         header is not allowed.
     */
    void setResponseHeader(in ACString header,
                           in ACString value,
                           in boolean merge);

    /**
     * Call this method to visit all response headers.  Calling
     * setResponseHeader while visiting response headers has undefined
     * behavior.  Don't do it!
     *
     * @param aVisitor
     *        the header visitor instance.
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    void visitResponseHeaders(in nsIHttpHeaderVisitor aVisitor);

    /**
     * Returns true if the server sent a "Cache-Control: no-store" response
     * header.
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    boolean isNoStoreResponse();

    /**
     * Returns true if the server sent the equivalent of a "Cache-control:
     * no-cache" response header.  Equivalent response headers include:
     * "Pragma: no-cache", "Expires: 0", and "Expires" with a date value
     * in the past relative to the value of the "Date" header.
     *
     * @throws NS_ERROR_NOT_AVAILABLE if called before the response
     *         has been received (before onStartRequest).
     */
    boolean isNoCacheResponse();
};
