Defined in comm-central/ mailnews/ base/ search/ public/ nsIMsgFilterCustomAction.idl

interface nsIMsgFilterCustomAction : nsISupports
{
  /* globally unique string to identify this filter action.
   * recommended form: ExtensionName@example.com#ActionName
   */
  readonly attribute ACString id;

  /* action name to display in action list. This should be localized. */
  readonly attribute AString name;

  /**
   * Is this custom action valid for a particular filter type?
   *
   * @param type    the filter type
   * @param scope   the search scope
   *
   * @return        true if valid
   */
  boolean isValidForType(in nsMsgFilterTypeType type, in nsMsgSearchScopeValue scope);

  /**
   * After the user inputs a particular action value for the action, determine
   * if that value is valid.
   *
   * @param actionValue          The value entered.
   * @param actionFolder         Folder in the filter list
   * @param filterType           Filter Type (Manual, OfflineMail, etc.)
   *
   * @return errorMessage        A localized message to display if invalid
   *                             Set to null if the actionValue is valid
   */
  AUTF8String validateActionValue(in AUTF8String actionValue,
                                  in nsIMsgFolder actionFolder,
                                  in nsMsgFilterTypeType filterType);

  /* allow duplicate actions in the same filter list? Default No. */
  attribute boolean allowDuplicates;

  /*
   * The custom action itself
   *
   * Generally for the apply method, folder-based methods give correct
   * results and are preferred if available. Otherwise, be careful
   * that the action does correct notifications to maintain counts, and correct
   * manipulations of both IMAP and local non-database storage of message
   * metadata.
   */

  /**
   * Apply the custom action to an array of messages
   *
   * @param msgHdrs      array of nsIMsgDBHdr objects of messages
   * @param actionValue  user-set value to use in the action
   * @param copyListener calling method (filterType Manual only)
   * @param filterType   type of filter being applied
   * @param msgWindow    message window
   */

   void apply(in nsIArray msgHdrs /* nsIMsgDBHdr array */,
              in AUTF8String actionValue,
              in nsIMsgCopyServiceListener copyListener,
              in nsMsgFilterTypeType filterType,
              in nsIMsgWindow msgWindow);

   /* does this action start an async action? If so, a copy listener must
    * be used to continue filter processing after the action. This only
    * applies to after-the-fact (manual) filters. Call OnStopCopy when done
    * using the copyListener to continue.
    */
   readonly attribute boolean isAsync;

   /// Does this action need the message body?
   readonly attribute boolean needsBody;
 };