From dd733df9c3f5cf38e8ff32190d2f463e8d0f1ea8 Mon Sep 17 00:00:00 2001
From: George Kiagiadakis <george.kiagiadakis@collabora.com>
Date: Thu, 10 Nov 2022 19:22:03 +0200
Subject: [PATCH] scripts/policy-desktop: add script for the
 filter-forward-format logic

---
 .../policy-desktop/filter-forward-format.lua  | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 src/scripts/policy-desktop/filter-forward-format.lua

diff --git a/src/scripts/policy-desktop/filter-forward-format.lua b/src/scripts/policy-desktop/filter-forward-format.lua
new file mode 100644
index 00000000..d5597f4e
--- /dev/null
+++ b/src/scripts/policy-desktop/filter-forward-format.lua
@@ -0,0 +1,114 @@
+-- WirePlumber
+--
+-- Copyright © 2022 Collabora Ltd.
+--
+-- SPDX-License-Identifier: MIT
+--
+-- Logic to "forward" the format set on special filter nodes to their
+-- virtual device peer node. This is for things like the "loopback" module,
+-- which always comes in pairs of 2 nodes, one stream and one virtual device.
+--
+-- FIXME: this script can be further improved
+
+local putils = require ("policy-utils")
+local config = require ("policy-config")
+
+function findAssociatedLinkGroupNode (si)
+  local si_props = si.properties
+  local link_group = si_props ["node.link-group"]
+  if link_group == nil then
+    return nil
+  end
+
+  local std_event_source = Plugin.find ("standard-event-source")
+  local om = std_event_source ["object-manager"]
+
+  -- get the associated media class
+  local assoc_direction = cutils.getTargetDirection (si_props)
+  local assoc_media_class = si_props ["media.type"] ..
+      (assoc_direction == "input" and "/Sink" or "/Source")
+
+  -- find the linkable with same link group and matching assoc media class
+  for assoc_si in om:iterate { type = "SiLinkable" } do
+    local assoc_props = assoc_si.properties
+    local assoc_link_group = assoc_props ["node.link-group"]
+    if assoc_link_group == link_group and
+        assoc_media_class == assoc_props ["media.class"] then
+      return assoc_si
+    end
+  end
+
+  return nil
+end
+
+function onLinkGroupPortsStateChanged (si, old_state, new_state)
+  local si_props = si.properties
+
+  -- only handle items with configured ports state
+  if new_state ~= "configured" then
+    return
+  end
+
+  Log.info (si, "ports format changed on " .. si_props ["node.name"])
+
+  -- find associated device
+  local si_device = findAssociatedLinkGroupNode (si)
+  if si_device ~= nil then
+    local device_node_name = si_device.properties ["node.name"]
+
+    -- get the stream format
+    local f, m = si:get_ports_format ()
+
+    -- unregister the device
+    Log.info (si_device, "unregistering " .. device_node_name)
+    si_device:remove ()
+
+    -- set new format in the device
+    Log.info (si_device, "setting new format in " .. device_node_name)
+    si_device:set_ports_format (f, m, function (item, e)
+      if e ~= nil then
+        Log.warning (item, "failed to configure ports in " ..
+          device_node_name .. ": " .. e)
+      end
+
+      -- register back the device
+      Log.info (item, "registering " .. device_node_name)
+      item:register ()
+    end)
+  end
+end
+
+SimpleEventHook {
+  name = "filter-forward-format@policy-node",
+  type = "on-event",
+  priority = HookPriority.NORMAL,
+  interests = {
+    EventInterest {
+      Constraint { "event.type", "=", "object-added" },
+      Constraint { "event.subject.type", "=", "linkable" },
+      Constraint { "item.factory.name", "c", "si-audio-adapter", "si-node" },
+      Constraint { "media.class", "#", "Stream/*", type = "pw-global" },
+      Constraint { "active-features", "!", 0, type = "gobject" },
+    },
+  },
+  execute = function (event)
+    local si = event:get_subject ()
+
+    -- Forward filters ports format to associated virtual devices if enabled
+    if config.filter_forward_format then
+      local si_props = si.properties
+      local link_group = si_props ["node.link-group"]
+      local si_flags = putils:get_flags (si.id)
+
+      -- only listen for ports state changed on audio filter streams
+      if si_flags.ports_state_signal ~= true and
+          si_props ["item.factory.name"] == "si-audio-adapter" and
+          si_props ["item.node.type"] == "stream" and
+          link_group ~= nil then
+        si:connect ("adapter-ports-state-changed", onLinkGroupPortsStateChanged)
+        si_flags.ports_state_signal = true
+        Log.info (si, "listening ports state changed on " .. si_props ["node.name"])
+      end
+    end
+  end
+}:register ()