/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ft=cpp tw=78 sw=2 et ts=8 : */
/* 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 "nsISupports.idl"

interface nsIURI;
interface nsIDOMNode;
interface nsIPrincipal;

/**
 * The type of nsIContentPolicy::TYPE_*
 */
typedef unsigned long nsContentPolicyType;

/**
 * Interface for content policy mechanism.  Implementations of this
 * interface can be used to control loading of various types of out-of-line
 * content, or processing of certain types of in-line content.
 *
 * WARNING: do not block the caller from shouldLoad or shouldProcess (e.g.,
 * by launching a dialog to prompt the user for something).
 */

[scriptable,uuid(b6a71698-c117-441d-86b9-480cf06e3952)]
interface nsIContentPolicy : nsISupports
{
  /**
   * Gecko/Firefox developers: Do not use TYPE_OTHER under any circumstances.
   *
   * Extension developers: Whenever it is reasonable, use one of the existing
   * content types. If none of the existing content types are right for
   * something you are doing, file a bug in the Core/DOM component that
   * includes a patch that adds your new content type to the end of the list of
   * TYPE_* constants here. But, don't start using your new content type until
   * your patch has been accepted, because it will be uncertain what exact
   * value and name your new content type will have; in that interim period,
   * use TYPE_OTHER. In your patch, document your new content type in the style
   * of the existing ones. In the bug you file, provide a more detailed
   * description of the new type of content you want Gecko to support, so that
   * the existing implementations of nsIContentPolicy can be properly modified
   * to deal with that new type of content.
   *
   * Implementations of nsIContentPolicy should treat this the same way they
   * treat unknown types, because existing users of TYPE_OTHER may be converted
   * to use new content types.
   */
  const nsContentPolicyType TYPE_OTHER = 1;

  /**
   * Indicates an executable script (such as JavaScript).
   */
  const nsContentPolicyType TYPE_SCRIPT = 2;

  /**
   * Indicates an image (e.g., IMG elements).
   */
  const nsContentPolicyType TYPE_IMAGE = 3;

  /**
   * Indicates a stylesheet (e.g., STYLE elements).
   */
  const nsContentPolicyType TYPE_STYLESHEET = 4;

  /**
   * Indicates a generic object (plugin-handled content typically falls under
   * this category).
   */
  const nsContentPolicyType TYPE_OBJECT = 5;

  /**
   * Indicates a document at the top-level (i.e., in a browser).
   */
  const nsContentPolicyType TYPE_DOCUMENT = 6;

  /**
   * Indicates a document contained within another document (e.g., IFRAMEs,
   * FRAMES, and OBJECTs).
   */
  const nsContentPolicyType TYPE_SUBDOCUMENT = 7;

  /**
   * Indicates a timed refresh.
   *
   * shouldLoad will never get this, because it does not represent content
   * to be loaded (the actual load triggered by the refresh will go through
   * shouldLoad as expected).
   *
   * shouldProcess will get this for, e.g., META Refresh elements and HTTP
   * Refresh headers.
   */
  const nsContentPolicyType TYPE_REFRESH = 8;

  /**
   * Indicates an XBL binding request, triggered either by -moz-binding CSS
   * property.
   */
  const nsContentPolicyType TYPE_XBL = 9;

  /**
   * Indicates a ping triggered by a click on <A PING="..."> element.
   */
  const nsContentPolicyType TYPE_PING = 10;

  /**
   * Indicates an XMLHttpRequest. Also used for document.load and for EventSource.
   */
  const nsContentPolicyType TYPE_XMLHTTPREQUEST = 11;
  const nsContentPolicyType TYPE_DATAREQUEST    = 11; // alias

  /**
   * Indicates a request by a plugin.
   */
  const nsContentPolicyType TYPE_OBJECT_SUBREQUEST = 12;

  /**
   * Indicates a DTD loaded by an XML document.
   */
  const nsContentPolicyType TYPE_DTD = 13;

  /**
   * Indicates a font loaded via @font-face rule.
   */
  const nsContentPolicyType TYPE_FONT = 14;

  /**
   * Indicates a video or audio load.
   */
  const nsContentPolicyType TYPE_MEDIA = 15;

  /**
   * Indicates a WebSocket load.
   */
  const nsContentPolicyType TYPE_WEBSOCKET = 16;

  /**
   * Indicates a Content Security Policy report.
   */
  const nsContentPolicyType TYPE_CSP_REPORT = 17;

  /**
   * Indicates a style sheet transformation.
   */
  const nsContentPolicyType TYPE_XSLT = 18;

  /**
   * Indicates a beacon post.
   */
  const nsContentPolicyType TYPE_BEACON = 19;

  /* When adding new content types, please update nsContentBlocker,
   * NS_CP_ContentTypeName, nsCSPContext, all nsIContentPolicy
   * implementations, and other things that are not listed here that are
   * related to nsIContentPolicy. */

  //////////////////////////////////////////////////////////////////////

  /**
   * Returned from shouldLoad or shouldProcess if the load or process request
   * is rejected based on details of the request.
   */
  const short REJECT_REQUEST = -1;

  /**
   * Returned from shouldLoad or shouldProcess if the load/process is rejected
   * based solely on its type (of the above flags).
   *
   * NOTE that it is not meant to stop future requests for this type--only the
   * current request.
   */
  const short REJECT_TYPE = -2;

  /**
   * Returned from shouldLoad or shouldProcess if the load/process is rejected
   * based on the server it is hosted on or requested from (aContentLocation or
   * aRequestOrigin), e.g., if you block an IMAGE because it is served from
   * goatse.cx (even if you don't necessarily block other types from that
   * server/domain).
   *
   * NOTE that it is not meant to stop future requests for this server--only the
   * current request.
   */
  const short REJECT_SERVER = -3;

  /**
   * Returned from shouldLoad or shouldProcess if the load/process is rejected
   * based on some other criteria. Mozilla callers will handle this like
   * REJECT_REQUEST; third-party implementors may, for example, use this to
   * direct their own callers to consult the extra parameter for additional
   * details.
   */
  const short REJECT_OTHER = -4;

  /**
   * Returned from shouldLoad or shouldProcess if the load or process request
   * is not rejected.
   */
  const short ACCEPT = 1;

  //////////////////////////////////////////////////////////////////////

  /**
   * Should the resource at this location be loaded?
   * ShouldLoad will be called before loading the resource at aContentLocation
   * to determine whether to start the load at all.
   *
   * @param aContentType      the type of content being tested. This will be one
   *                          one of the TYPE_* constants.
   *
   * @param aContentLocation  the location of the content being checked; must
   *                          not be null
   *
   * @param aRequestOrigin    OPTIONAL. the location of the resource that
   *                          initiated this load request; can be null if
   *                          inapplicable
   *
   * @param aContext          OPTIONAL. the nsIDOMNode or nsIDOMWindow that
   *                          initiated the request, or something that can QI
   *                          to one of those; can be null if inapplicable.
   *                          Note that for navigation events (new windows and
   *                          link clicks), this is the NEW window.
   *
   * @param aMimeTypeGuess    OPTIONAL. a guess for the requested content's
   *                          MIME type, based on information available to
   *                          the request initiator (e.g., an OBJECT's type
   *                          attribute); does not reliably reflect the
   *                          actual MIME type of the requested content
   *
   * @param aExtra            an OPTIONAL argument, pass-through for non-Gecko
   *                          callers to pass extra data to callees.
   *
   * @param aRequestPrincipal an OPTIONAL argument, defines the principal that
   *                          caused the load. This is optional only for
   *                          non-gecko code: all gecko code should set this
   *                          argument.  For navigation events, this is
   *                          the principal of the page that caused this load.
   *
   * @return ACCEPT or REJECT_*
   *
   * @note shouldLoad can be called while the DOM and layout of the document
   * involved is in an inconsistent state.  This means that implementors of
   * this method MUST NOT do any of the following:
   * 1)  Modify the DOM in any way (e.g. setting attributes is a no-no).
   * 2)  Query any DOM properties that depend on layout (e.g. offset*
   *     properties).
   * 3)  Query any DOM properties that depend on style (e.g. computed style).
   * 4)  Query any DOM properties that depend on the current state of the DOM
   *     outside the "context" node (e.g. lengths of node lists).
   * 5)  [JavaScript implementations only] Access properties of any sort on any
   *     object without using XPCNativeWrapper (either explicitly or
   *     implicitly).  Due to various DOM0 things, this leads to item 4.
   * If you do any of these things in your shouldLoad implementation, expect
   * unpredictable behavior, possibly including crashes, content not showing
   * up, content showing up doubled, etc.  If you need to do any of the things
   * above, do them off timeout or event.
   */
  short shouldLoad(in nsContentPolicyType aContentType,
                   in nsIURI        aContentLocation,
                   in nsIURI        aRequestOrigin,
                   in nsISupports   aContext,
                   in ACString      aMimeTypeGuess,
                   in nsISupports   aExtra,
                   [optional] in nsIPrincipal  aRequestPrincipal);

  /**
   * Should the resource be processed?
   * ShouldProcess will be called once all the information passed to it has
   * been determined about the resource, typically after part of the resource
   * has been loaded.
   *
   * @param aContentType      the type of content being tested. This will be one
   *                          one of the TYPE_* constants.
   *
   * @param aContentLocation  OPTIONAL; the location of the resource being
   *                          requested: MAY be, e.g., a post-redirection URI
   *                          for the resource.
   *
   * @param aRequestOrigin    OPTIONAL. the location of the resource that
   *                          initiated this load request; can be null if
   *                          inapplicable
   *
   * @param aContext          OPTIONAL. the nsIDOMNode or nsIDOMWindow that
   *                          initiated the request, or something that can QI
   *                          to one of those; can be null if inapplicable.
   *
   * @param aMimeType         the MIME type of the requested resource (e.g.,
   *                          image/png), as reported by the networking library,
   *                          if available (may be empty if inappropriate for
   *                          the type, e.g., TYPE_REFRESH).
   *
   * @param aExtra            an OPTIONAL argument, pass-through for non-Gecko
   *                          callers to pass extra data to callees.
   *
   * @return ACCEPT or REJECT_*
   *
   * @note shouldProcess can be called while the DOM and layout of the document
   * involved is in an inconsistent state.  See the note on shouldLoad to see
   * what this means for implementors of this method.
   */
  short shouldProcess(in nsContentPolicyType aContentType,
                      in nsIURI        aContentLocation,
                      in nsIURI        aRequestOrigin,
                      in nsISupports   aContext,
                      in ACString      aMimeType,
                      in nsISupports   aExtra,
                      [optional] in nsIPrincipal  aRequestPrincipal);

};
