From 914867bd137a4d79d59315980ad8046bb9d9d176 Mon Sep 17 00:00:00 2001
From: George Kiagiadakis <george.kiagiadakis@collabora.com>
Date: Fri, 8 Oct 2021 01:10:30 +0300
Subject: [PATCH] policy-node: cleanup target.node metadata when the default
 sink changes

When the default node changes to become the same as the target.node value
that was set in the metadata, remove this target.node from the metadata
to let the stream follow the default.

Also cleanup the useless target.node == -1 metadata that pipewire-pulse sets
when a stream is moved to the default node

Fixes #65
---
 src/scripts/policy-node.lua | 67 +++++++++++++++++++++++++++++--------
 1 file changed, 53 insertions(+), 14 deletions(-)

diff --git a/src/scripts/policy-node.lua b/src/scripts/policy-node.lua
index 84b907a5..3a27e9c4 100644
--- a/src/scripts/policy-node.lua
+++ b/src/scripts/policy-node.lua
@@ -176,15 +176,31 @@ function findDefinedTarget (properties)
       or findTargetByNodeTargetProperty (properties)
 end
 
+function getTargetDirection(properties)
+  local target_direction = nil
+  if properties["item.node.direction"] == "output" or
+     (properties["item.node.direction"] == "input" and
+        parseBool(properties["stream.capture.sink"])) then
+    target_direction = "input"
+  else
+    target_direction = "output"
+  end
+  return target_direction
+end
+
+function getDefaultNode(properties, target_direction)
+  local target_media_class =
+        properties["media.type"] ..
+        (target_direction == "input" and "/Sink" or "/Source")
+  return default_nodes:call("get-default-node", target_media_class)
+end
+
 -- Try to locate a valid target node that was NOT explicitly defined by the user
 -- `properties` must be the properties dictionary of the session item
 -- that is currently being handled
 function findUndefinedTarget (properties)
   local function findTargetByDefaultNode (properties, target_direction)
-    local target_media_class =
-        properties["media.type"] ..
-        (target_direction == "input" and "/Sink" or "/Source")
-    local def_id = default_nodes:call("get-default-node", target_media_class)
+    local def_id = getDefaultNode(properties, target_direction)
     if def_id ~= Id.INVALID then
       local si_target = linkables_om:lookup {
         Constraint { "node.id", "=", def_id },
@@ -209,15 +225,7 @@ function findUndefinedTarget (properties)
     return nil
   end
 
-  local target_direction = nil
-  if properties["item.node.direction"] == "output" or
-     (properties["item.node.direction"] == "input" and
-        parseBool(properties["stream.capture.sink"])) then
-    target_direction = "input"
-  else
-    target_direction = "output"
-  end
-
+  local target_direction = getTargetDirection(properties)
   return findTargetByDefaultNode (properties, target_direction)
       or findTargetByFirstAvailable (properties, target_direction)
 end
@@ -370,9 +378,40 @@ links_om = ObjectManager {
   }
 }
 
+function cleanupTargetNodeMetadata()
+  local metadata = metadata_om:lookup()
+  if metadata then
+    local to_remove = {}
+    for s, k, t, v in metadata:iterate(Id.ANY) do
+      if k == "target.node" then
+        if v == "-1" then
+          -- target.node == -1 is useless, it means the default node
+          table.insert(to_remove, s)
+        else
+          -- if the target.node value is the same as the default node
+          -- that would be selected for this stream, remove it
+          local si = linkables_om:lookup { Constraint { "node.id", "=", s } }
+          local properties = si.properties
+          local def_id = getDefaultNode(properties, getTargetDirection(properties))
+          if tostring(def_id) == v then
+            table.insert(to_remove, s)
+          end
+        end
+      end
+    end
+
+    for _, s in ipairs(to_remove) do
+      metadata:set(s, "target.node", nil, nil)
+    end
+  end
+end
+
 -- listen for default node changes if config.follow is enabled
 if config.follow then
-  default_nodes:connect("changed", rescan)
+  default_nodes:connect("changed", function ()
+    cleanupTargetNodeMetadata()
+    rescan()
+  end)
 end
 
 -- listen for target.node metadata changes if config.move is enabled