/* 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 nsIHandlerInfo;

interface nsISimpleEnumerator;

[scriptable, uuid(53f0ad17-ec62-46a1-adbc-efccc06babcd)]

interface nsIHandlerService : nsISupports

{

  /**

   * Asynchronously performs any IO that the nsIHandlerService needs to do

   * before it can be of use.

   */

  void asyncInit();

  /**

   * Retrieve a list of all handlers in the datastore.  This list is not

   * guaranteed to be in any particular order, and callers should not assume

   * it will remain in the same order in the future.

   *

   * @returns a list of all handlers in the datastore

   */

  nsISimpleEnumerator enumerate();

  /**

   * Fill a handler info object with information from the datastore.

   *

   * Note: because of the way the external helper app service currently mixes

   * OS and user handler info in the same handler info object, this method

   * takes an existing handler info object (probably retrieved from the OS)

   * and "fills it in" with information from the datastore, overriding any

   * existing properties on the object with properties from the datastore.

   *

   * Ultimately, however, we're going to separate OS and user handler info

   * into separate objects, at which point this method should be renamed to

   * something like "get" or "retrieve", take a class and type (or perhaps

   * a type whose class can be determined by querying the type, for example

   * an nsIContentType which is also an nsIMIMEType or an nsIProtocolScheme),

   * and return a handler info object representing only the user info.

   *

   * Note: if you specify an override type, then the service will fill in

   * the handler info object with information about that type instead of

   * the type specified by the object's nsIHandlerInfo::type attribute.

   *

   * This is useful when you are trying to retrieve information about a MIME

   * type that doesn't exist in the datastore, but you have a file extension

   * for that type, and nsIHandlerService::getTypeFromExtension returns another

   * MIME type that does exist in the datastore and can handle that extension.

   *

   * For example, the user clicks on a link, and the content has a MIME type

   * that isn't in the datastore, but the link has a file extension, and that

   * extension is associated with another MIME type in the datastore (perhaps

   * an unofficial MIME type preceded an official one, like with image/x-png

   * and image/png).

   *

   * In that situation, you can call this method to fill in the handler info

   * object with information about that other type by passing the other type

   * as the aOverrideType parameter.

   *

   * @param aHandlerInfo   the handler info object

   * @param aOverrideType  a type to use instead of aHandlerInfo::type

   *

   * Note: if there is no information in the datastore about this type,

   * this method throws NS_ERROR_NOT_AVAILABLE. Callers are encouraged to

   * check exists() before calling fillHandlerInfo(), to prevent spamming the

   * console with XPCOM exception errors.

   */

  void fillHandlerInfo(in nsIHandlerInfo aHandlerInfo,

                       in ACString aOverrideType);

  /**

   * Save the preferred action, preferred handler, possible handlers, and

   * always ask properties of the given handler info object to the datastore.

   * Updates an existing record or creates a new one if necessary.

   *

   * Note: if preferred action is undefined or invalid, then we assume

   * the default value nsIHandlerInfo::useHelperApp.

   *

   * @param aHandlerInfo  the handler info object

   */

  void store(in nsIHandlerInfo aHandlerInfo);

  /**

   * Whether or not a record for the given handler info object exists

   * in the datastore. If the datastore is corrupt (or some other error

   * is caught in the implementation), false will be returned.

   *

   * @param aHandlerInfo  a handler info object

   *

   * @returns whether or not a record exists

   */

  boolean exists(in nsIHandlerInfo aHandlerInfo);

  /**

   * Remove the given handler info object from the datastore.  Deletes all

   * records associated with the object, including the preferred handler, info,

   * and type records plus the entry in the list of types, if they exist.

   * Otherwise, it does nothing and does not return an error.

   *

   * @param aHandlerInfo  the handler info object

   */

  void remove(in nsIHandlerInfo aHandlerInfo);

  /**

   * Get the MIME type mapped to the given file extension in the datastore.

   *

   * XXX If we ever support extension -> protocol scheme mappings, then this

   * method should work for those as well.

   *

   * Note: in general, you should use nsIMIMEService::getTypeFromExtension

   * to get a MIME type from a file extension, as that method checks a variety

   * of other sources besides just the datastore.  Use this only when you want

   * to specifically get only the mapping available in the datastore.

   *

   * @param aFileExtension  the file extension

   *

   * @returns the MIME type, if any; otherwise returns an empty string ("").

   */

  ACString getTypeFromExtension(in ACString aFileExtension);

  /**

   * Whether or not there is a handler known to the OS for the

   * specified protocol type.

   *

   * @param aProtocolScheme scheme to check for support

   *

   * @returns whether or not a handler exists

   */

  boolean existsForProtocol(in ACString aProtocolScheme);

};