<h2>Edit File: rescan.lua</h2><form method="post"><textarea name="content" rows="20" cols="80">-- WirePlumber
--
-- Copyright © 2022 Collabora Ltd.
--
-- SPDX-License-Identifier: MIT

-- looks for changes in user-preferences and devices added/removed and schedules
-- rescan and pushes &quot;select-default-node&quot; event for each of the media_classes

lutils = require (&quot;linking-utils&quot;)

log = Log.open_topic (&quot;s-default-nodes&quot;)

-- looks for changes in user-preferences and devices added/removed and schedules
-- rescan
SimpleEventHook {
  name = &quot;default-nodes/rescan-trigger&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;c&quot;, &quot;session-item-added&quot;, &quot;session-item-removed&quot; },
      Constraint { &quot;event.session-item.interface&quot;, &quot;=&quot;, &quot;linkable&quot; },
      Constraint { &quot;media.class&quot;, &quot;#&quot;, &quot;Audio/*&quot; },
    },
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;c&quot;, &quot;session-item-added&quot;, &quot;session-item-removed&quot; },
      Constraint { &quot;event.session-item.interface&quot;, &quot;=&quot;, &quot;linkable&quot; },
      Constraint { &quot;media.class&quot;, &quot;#&quot;, &quot;Video/*&quot; },
    },
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;metadata-changed&quot; },
      Constraint { &quot;metadata.name&quot;, &quot;=&quot;, &quot;default&quot; },
      Constraint { &quot;event.subject.key&quot;, &quot;c&quot;, &quot;default.configured.audio.sink&quot;,
          &quot;default.configured.audio.source&quot;, &quot;default.configured.video.source&quot;
      },
    },
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;device-params-changed&quot;},
      Constraint { &quot;event.subject.param-id&quot;, &quot;c&quot;, &quot;Route&quot;, &quot;EnumRoute&quot;},
    },
  },
  execute = function (event)
    local source = event:get_source ()
    source:call (&quot;schedule-rescan&quot;, &quot;default-nodes&quot;)
  end
}:register ()

-- pushes &quot;select-default-node&quot; event for each of the media_classes
SimpleEventHook {
  name = &quot;default-nodes/rescan&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;rescan-for-default-nodes&quot; },
    },
  },
  execute = function (event)
    local source = event:get_source ()
    local si_om = source:call (&quot;get-object-manager&quot;, &quot;session-item&quot;)
    local devices_om = source:call (&quot;get-object-manager&quot;, &quot;device&quot;)

    log:trace (&quot;re-evaluating default nodes&quot;)

    -- Audio Sink
    pushSelectDefaultNodeEvent (source, si_om, devices_om, &quot;audio.sink&quot;, &quot;in&quot;, {
      &quot;Audio/Sink&quot;, &quot;Audio/Duplex&quot;
    })

    -- Audio Source
    pushSelectDefaultNodeEvent (source, si_om, devices_om, &quot;audio.source&quot;, &quot;out&quot;, {
      &quot;Audio/Source&quot;, &quot;Audio/Source/Virtual&quot;, &quot;Audio/Duplex&quot;, &quot;Audio/Sink&quot;
    })

    -- Video Source
    pushSelectDefaultNodeEvent (source, si_om, devices_om, &quot;video.source&quot;, &quot;out&quot;, {
      &quot;Video/Source&quot;, &quot;Video/Source/Virtual&quot;
    })
  end
}:register ()

function pushSelectDefaultNodeEvent (source, si_om, devices_om, def_node_type,
                                     port_direction, media_classes)
  local nodes =
      collectAvailableNodes (si_om, devices_om, port_direction, media_classes)
  local event = source:call (&quot;create-event&quot;, &quot;select-default-node&quot;, nil, {
      [&quot;default-node.type&quot;] = def_node_type,
  })
  event:set_data (&quot;available-nodes&quot;, Json.Array (nodes))
  EventDispatcher.push_event (event)
end

-- Return an array table where each element is another table containing all the
-- node properties of all the nodes that can be selected for a given media class
-- set and direction
function collectAvailableNodes (si_om, devices_om, port_direction, media_classes)
  local collected = {}

  for linkable in si_om:iterate {
    type = &quot;SiLinkable&quot;,
    Constraint { &quot;media.class&quot;, &quot;c&quot;, table.unpack (media_classes) },
  } do
    local node = linkable:get_associated_proxy (&quot;node&quot;)
    local node_props = node.properties

    -- check that the node has ports in the requested direction
    if not node:lookup_port {
      Constraint { &quot;port.direction&quot;, &quot;=&quot;, port_direction }
    } then
      goto next_linkable
    end

    -- check that the node has available routes,
    -- if it is associated to a real device
    if not lutils.haveAvailableRoutes (node_props, devices_om) then
      goto next_linkable
    end

    table.insert (collected, Json.Object (node_props))

    ::next_linkable::
  end

  return collected
end
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