<h2>Edit File: get-filter-from-target.lua</h2><form method="post"><textarea name="content" rows="20" cols="80">-- WirePlumber
--
-- Copyright © 2023 Collabora Ltd.
--
-- SPDX-License-Identifier: MIT
--
-- Check if the target node is a filter target.

lutils = require (&quot;linking-utils&quot;)
cutils = require (&quot;common-utils&quot;)
futils = require (&quot;filter-utils&quot;)
log = Log.open_topic (&quot;s-linking&quot;)

SimpleEventHook {
  name = &quot;linking/get-filter-from-target&quot;,
  after = { &quot;linking/find-defined-target&quot;,
            &quot;linking/find-filter-target&quot;,
            &quot;linking/find-media-role-target&quot;,
            &quot;linking/find-default-target&quot;,
            &quot;linking/find-best-target&quot; },
  before = &quot;linking/prepare-link&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;select-target&quot; },
    },
  },
  execute = function (event)
    local source, om, si, si_props, si_flags, target =
        lutils:unwrap_select_target_event (event)

    -- bypass the hook if the target was not found or if it is a role-based policy target
    if target == nil or lutils.is_role_policy_target (si_props, target.properties) then
      return
    end

    -- bypass the hook if the session item is a smart filter
    local node = si:get_associated_proxy (&quot;node&quot;)
    local node_props = node.properties
    local link_group = node_props [&quot;node.link-group&quot;]
    local target_direction = cutils.getTargetDirection (si.properties)
    if link_group ~= nil and
        futils.is_filter_smart (target_direction, link_group) then
      return
    end

    -- bypass the hook if the target is an audio group
    local target_node = target:get_associated_proxy (&quot;node&quot;)
    local target_node_props = target_node.properties
    local target_audio_group = target_node_props [&quot;session.audio-group&quot;]
    if target_audio_group ~= nil then
      return
    end

    -- bypass the hook if target is defined, is a filter and is targetable
    local target_link_group = target_node_props [&quot;node.link-group&quot;]
    if target_link_group ~= nil and si_flags.has_defined_target then
      if futils.is_filter_smart (target_direction, target_link_group) and
          not futils.is_filter_disabled (target_direction, target_link_group) and
          futils.is_filter_targetable (target_direction, target_link_group) then
        return
      end
    end

    -- Get the filter from the given target if it exists, otherwise get the
    -- default filter, but only if target was not defined
    local media_type = si_props[&quot;media.type&quot;]
    local filter_target = futils.get_filter_from_target (target_direction, media_type, target)
    if filter_target ~= nil then
      target = filter_target
      log:info (si, &quot;... got filter for given target&quot;)
    elseif filter_target == nil and not si_flags.has_defined_target then
      filter_target = futils.get_filter_from_target (target_direction, media_type, nil)
      if filter_target ~= nil then
        target = filter_target
        log:info (si, &quot;... got default filter for given target&quot;)
      end
    end

    local can_passthrough, passthrough_compatible
    if target ~= nil then
      passthrough_compatible, can_passthrough =
      lutils.checkPassthroughCompatibility (si, target)
      if lutils.canLink (si_props, target) and passthrough_compatible then
        target_picked = true;
      end
    end

    if target_picked then
      log:info (si,
        string.format (&quot;... target picked: %s (%s), can_passthrough:%s&quot;,
          tostring (target.properties [&quot;node.name&quot;]),
          tostring (target.properties [&quot;node.id&quot;]),
          tostring (can_passthrough)))
      si_flags.can_passthrough = can_passthrough
      event:set_data (&quot;target&quot;, target)
    end
  end
}:register ()
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