<?xml version="1.0" encoding="UTF-8"?>
<protocol name="xx_session_management_v1">
  <copyright>
    Copyright 2018 Mike Blumenkrantz
    Copyright 2018 Samsung Electronics Co., Ltd
    Copyright 2018 Red Hat Inc.

    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:

    The above copyright notice and this permission notice (including the next
    paragraph) shall be included in all copies or substantial portions of the
    Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
  </copyright>

  <description summary="Protocol for managing application sessions">
    This description provides a high-level overview of the interplay between
    the interfaces defined this protocol. For details, see the protocol
    specification.

    The xx_session_manager protocol declares interfaces necessary to
    allow clients to restore toplevel state from previous executions. The
    xx_session_manager_v1.get_session request can be used to obtain a
    xx_session_v1 resource representing the state of a set of toplevels.

    Clients may obtain the session string to use in future calls through
    the xx_session_v1.created event. Compositors will use this string
    as an identifiable token for future runs, possibly storing data about
    the related toplevels in persistent storage.

    Toplevels are managed through the xx_session_v1.add_toplevel and
    xx_session_toplevel_v1.remove pair of requests. Clients will explicitly
    request a toplevel to be restored according to prior state through the
    xx_session_v1.restore_toplevel request before the toplevel is mapped.

    Warning! The protocol described in this file is currently in the testing
    phase. Backward compatible changes may be added together with the
    corresponding interface version bump. Backward incompatible changes can
    only be done by creating a new major version of the extension.
  </description>

  <interface name="xx_session_manager_v1" version="1">
    <description summary="manage sessions for applications">
      The xx_session_manager interface defines base requests for creating and
      managing a session for an application. Sessions persist across application
      and compositor restarts unless explicitly destroyed. A session is created
      for the purpose of maintaining an application's xdg_toplevel surfaces
      across compositor or application restarts. The compositor should remember
      as many states as possible for surfaces in a given session, but there is
      no requirement for which states must be remembered.
    </description>

    <enum name="error">
      <entry name="in_use" summary="a requested session is already in use"
	value="1"/>
    </enum>

    <enum name="reason">
      <description summary="reason for getting a session">
	The reason may determine in what way a session restores the window
	management state of associated toplevels.

	For example newly launched applications might be launched on the active
	workspace with restored size and position, while a recovered
	applications might restore additional state such as active workspace and
	stacking order.
      </description>
      <entry name="launch" value="1">
	<description summary="an app is newly launched">
	  A new app instance is launched, for example from an app launcher.
	</description>
      </entry>
      <entry name="recover" value="2">
	<description summary="an app recovered">
	  A app instance is recovering from for example a compositor or app crash.
	</description>
      </entry>
      <entry name="session_restore" value="3">
	<description summary="an app restored">
	  A app instance is restored, for example part of a restored session, or
	  restored from having been temporarily terminated due to resource
	  constraints.
	</description>
      </entry>
    </enum>

    <request name="destroy" type="destructor">
      <description summary="Destroy this object">
	This has no effect other than to destroy the xx_session_manager object.
      </description>
    </request>

    <request name="get_session">
      <description summary="create or restore a session">
	Create a session object corresponding to either an existing session
	identified by the given session identifier string or a new session.
	While the session object exists, the session is considered to be "in
	use".

	If a identifier string represents a session that is currently actively
	in use by the the same client, an 'in_use' error is raised. If some
	other client is currently using the same session, the new session will
	replace managing the associated state.

	NULL is passed to initiate a new session. If an id is passed which does
	not represent a valid session, the compositor treats it as if NULL had
	been passed.

	A client is allowed to have any number of in use sessions at the same
	time.
      </description>
      <arg name="id" type="new_id" interface="xx_session_v1"/>
      <arg name="reason" type="uint" enum="reason"
	   summary="reason for session"/>
      <arg name="session" type="string"
	   summary="the session to restore"
	   allow-null="true"/>
    </request>
  </interface>

  <interface name="xx_session_v1" version="1">
    <description summary="A session for an application">
      A xx_session_v1 object represents a session for an application. While the
      object exists, all surfaces which have been added to the session will
      have states stored by the compositor which can be reapplied at a later
      time. Two sessions cannot exist for the same identifier string.

      States for surfaces added to a session are automatically updated by the
      compositor when they are changed.

      Surfaces which have been added to a session are automatically removed from
      the session if xdg_toplevel.destroy is called for the surface.
    </description>

    <enum name="error">
      <entry name="invalid_restore"
	     summary="restore cannot be performed after initial toplevel commit"
	     value="1"/>
      <entry name="name_in_use"
	     summary="toplevel name is already in used"
	     value="2"/>
      <entry name="already_mapped"
	     summary="toplevel was already mapped when restored"
	     value="3"/>
    </enum>

    <request name="destroy" type="destructor">
      <description summary="Destroy the session">
	Destroy a session object, preserving the current state but not continuing
	to make further updates if state changes occur. This makes the associated
	xx_toplevel_session_v1 objects inert.
      </description>
    </request>

    <request name="remove" type="destructor">
      <description summary="Remove the session">
	Remove the session, making it no longer available for restoration. A
	compositor should in response to this request remove the data related to
	this session from its storage.
      </description>
    </request>

    <request name="add_toplevel">
      <description summary="add a new surface to the session">
	Attempt to add a given surface to the session. The passed name is used
	to identify what window is being restored, and may be used store window
	specific state within the session.

	Calling this with a toplevel that is already managed by the session with
	the same associated will raise an in_use error.
      </description>
      <arg name="id" type="new_id" interface="xx_toplevel_session_v1"/>
      <arg name="toplevel" type="object" interface="xdg_toplevel"/>
      <arg name="name" type="string"/>
    </request>

    <request name="restore_toplevel">
      <description summary="restore a surface state">
	Inform the compositor that the toplevel associated with the passed name
	should have its window management state restored.

	Calling this with a toplevel that is already managed by the session with
	the same associated will raise an in_use error.

	This request must be called prior to the first commit on the associated
	wl_surface, otherwise an already_mapped error is raised.

	As part of the initial configure sequence, if the toplevel was
	successfully restored, a xx_toplevel_session_v1.restored event is
	emitted. See the xx_toplevel_session_v1.restored event for further
	details.
      </description>
      <arg name="id" type="new_id" interface="xx_toplevel_session_v1"/>
      <arg name="toplevel" type="object" interface="xdg_toplevel"/>
      <arg name="name" type="string"/>
    </request>

    <event name="created">
      <description summary="newly-created session id">
	Emitted at most once some time after getting a new session object. It
	means that no previous state was restored, and a new session was created.
	The passed id can be used to restore previous sessions.
      </description>
      <arg name="id" type="string"/>
    </event>

    <event name="restored">
      <description summary="the session has been restored">
	Emitted at most once some time after getting a new session object. It
	means that previous state was at least partially restored. The same id
	can again be used to restore previous sessions.
      </description>
    </event>

    <event name="replaced">
      <description summary="the session has been restored">
	Emitted at most once, if the session was taken over by some other
	client. When this happens, the session and all its toplevel session
	objects become inert, and should be destroyed.
      </description>
    </event>
  </interface>

  <interface name="xx_toplevel_session_v1" version="1">
    <request name="destroy" type="destructor">
      <description summary="Destroy the object">
	Destroy the object. This has no effect window management of the
	associated toplevel.
      </description>
    </request>

    <request name="remove" type="destructor">
      <description summary="remove a surface from the session">
	Remove a specified surface from the session and render any corresponding
	xx_toplevel_session_v1 object inert. The compositor should remove any
	data related to the toplevel in the corresponding session from its internal
	storage.
      </description>
    </request>

    <event name="restored">
      <description summary="a toplevel's session has been restored">
	The "restored" event is emitted prior to the first
	xdg_toplevel.configure for the toplevel. It will only be emitted after
	xx_session_v1.restore_toplevel, and the initial empty surface state has
	been applied, and it indicates that the surface's session is being
	restored with this configure event.
      </description>
      <arg name="surface" type="object" interface="xdg_toplevel"/>
    </event>
  </interface>
</protocol>
