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

-- the script states the default nodes from the user preferences, it has hooks
-- which stores the user preferences(it stores not just the current preference
-- but all the previous preferences) in to the state file, retrieves them from
-- state file during the bootup, finally it has a hook which finds a default
-- node out of the user preferences

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

nutils = require (&quot;node-utils&quot;)

-- the state storage
state = nil
state_table = nil

find_stored_default_node_hook = SimpleEventHook {
  name = &quot;default-nodes/find-stored-default-node&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;select-default-node&quot; },
    },
  },
  execute = function (event)
    local props = event:get_properties ()
    local available_nodes = event:get_data (&quot;available-nodes&quot;)
    local selected_prio = event:get_data (&quot;selected-node-priority&quot;) or 0
    local selected_node = event:get_data (&quot;selected-node&quot;)

    available_nodes = available_nodes and available_nodes:parse ()
    if not available_nodes then
      return
    end

    local stored = collectStored (props [&quot;default-node.type&quot;])

    -- Check if any of the available nodes matches any of the configured
    for _, node_props in ipairs (available_nodes) do
      local name = node_props [&quot;node.name&quot;]

      for i, v in ipairs (stored) do
        if name == v then
          local priority = nutils.get_session_priority (node_props)
          priority = priority + 20001 - i

          if priority &gt; selected_prio then
            selected_prio = priority
            selected_node = name
          end

          break
        end
      end
    end

    if selected_node then
      event:set_data (&quot;selected-node-priority&quot;, selected_prio)
      event:set_data (&quot;selected-node&quot;, selected_node)
    end
  end
}

store_configured_default_nodes_hook = SimpleEventHook {
  name = &quot;default-nodes/store-configured-default-nodes&quot;,
  interests = {
    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;
      },
    },
  },
  execute = function (event)
    local props = event:get_properties ()
    -- get the part after &quot;default.configured.&quot; (= 19 chars)
    local def_node_type = props [&quot;event.subject.key&quot;]:sub (20)
    local new_value = props [&quot;event.subject.value&quot;]
    local new_stored = {}

    if new_value then
      new_value = Json.Raw (new_value):parse () [&quot;name&quot;]
    end

    if new_value then
      local stored = collectStored (def_node_type)
      local pos = #stored + 1

      -- find if the current configured value is already in the stack
      for i, v in ipairs (stored) do
        if v == new_value then
          pos = i
          break
        end
      end

      -- insert at the top and shift the remaining to fill the gap
      new_stored [1] = new_value
      if pos &gt; 1 then
        table.move (stored, 1, pos-1, 2, new_stored)
      end
      if pos &lt; #stored then
        table.move (stored, pos+1, #stored, pos+1, new_stored)
      end
    end

    updateStored (def_node_type, new_stored)
  end
}

-- set initial values
metadata_added_hook = SimpleEventHook {
  name = &quot;default-nodes/metadata-added&quot;,
  interests = {
    EventInterest {
      Constraint { &quot;event.type&quot;, &quot;=&quot;, &quot;metadata-added&quot; },
      Constraint { &quot;metadata.name&quot;, &quot;=&quot;, &quot;default&quot; },
    },
  },
  execute = function (event)
    local types = { &quot;audio.sink&quot;, &quot;audio.source&quot;, &quot;video.source&quot; }
    local source = event:get_source ()
    local om = source:call (&quot;get-object-manager&quot;, &quot;metadata&quot;)
    local metadata = om:lookup { Constraint { &quot;metadata.name&quot;, &quot;=&quot;, &quot;default&quot; } }

    for _, t in ipairs (types) do
      local v = state_table [&quot;default.configured.&quot; .. t]
      if v then
        metadata:set (0, &quot;default.configured.&quot; .. t, &quot;Spa:String:JSON&quot;,
                      Json.Object { [&quot;name&quot;] = v }:to_string ())
      end
    end
  end
}

-- Collect all the previously configured node names from the state file
function collectStored (def_node_type)
  local stored = {}
  local key_base = &quot;default.configured.&quot; .. def_node_type
  local key = key_base

  local index = 0
  repeat
    local v = state_table [key]
    table.insert (stored, v)
    key = key_base .. &quot;.&quot; .. tostring (index)
    index = index + 1
  until v == nil

  return stored
end

-- Store the given node names in the state file
function updateStored (def_node_type, stored)
  local key_base = &quot;default.configured.&quot; .. def_node_type
  local key = key_base

  local index = 0
  for _, v in ipairs (stored) do
    state_table [key] = v
    key = key_base .. &quot;.&quot; .. tostring (index)
    index = index + 1
  end

  -- erase the rest, if any
  repeat
    local v = state_table [key]
    state_table [key] = nil
    key = key_base .. &quot;.&quot; .. tostring (index)
    index = index + 1
  until v == nil

  state:save_after_timeout (state_table)
end

function toggleState (enable)
  if enable and not state then
    state = State (&quot;default-nodes&quot;)
    state_table = state:load ()
    find_stored_default_node_hook:register ()
    store_configured_default_nodes_hook:register ()
    metadata_added_hook:register ()
  elseif not enable and state then
    state = nil
    state_table = nil
    find_stored_default_node_hook:remove ()
    store_configured_default_nodes_hook:remove ()
    metadata_added_hook:remove ()
  end
end

Settings.subscribe (&quot;node.restore-default-targets&quot;, function ()
  toggleState (Settings.get_boolean (&quot;node.restore-default-targets&quot;))
end)
toggleState (Settings.get_boolean (&quot;node.restore-default-targets&quot;))
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