wireplumber/src/scripts/monitors/bluez-midi.lua

-- WirePlumber
--
-- Copyright © 2022 Pauli Virtanen
--    @author Pauli Virtanen
--
-- SPDX-License-Identifier: MIT

local cutils = require ("common-utils")
log = Log.open_topic ("s-monitors")

local defaults = {}
defaults.properties = Json.Object {}
defaults.servers = Json.Array { "bluez_midi.server" }

local config = {}
config.properties = Conf.get_section (
    "monitor.bluetooth-midi.properties", defaults.properties): parse ()
config.servers = Conf.get_section (
    "monitor.bluetooth-midi.servers", defaults.servers): parse ()

-- unique device/node name tables
node_names_table = nil
id_to_name_table = nil

function setLatencyOffset(node, offset_msec)
  if not offset_msec then
    return
  end

  local props = { "Spa:Pod:Object:Param:Props", "Props" }
  props.latencyOffsetNsec = tonumber(offset_msec) * 1000000

  local param = Pod.Object(props)
  log:debug(param, "setting latency offset on " .. tostring(node))
  node:set_param("Props", param)
end

function createNode(parent, id, type, factory, properties)
  properties["factory.name"] = factory

  -- set the node description
  local desc = properties["node.description"]
  -- sanitize description, replace ':' with ' '
  properties["node.description"] = desc:gsub("(:)", " ")

  -- set the node name
  local name =
      "bluez_midi." .. properties["api.bluez5.address"]
  -- sanitize name
  name = name:gsub("([^%w_%-%.])", "_")
  -- deduplicate nodes with the same name
  properties["node.name"] = name
  for counter = 2, 99, 1 do
    if node_names_table[properties["node.name"]] ~= true then
      node_names_table[properties["node.name"]] = true
      break
    end
    properties["node.name"] = name .. "." .. counter
  end

  properties["api.glib.mainloop"] = "true"

  -- apply properties from bluetooth.conf
  cutils.evaluateRulesApplyProperties (properties, "monitor.bluetooth-midi.rules")

  local latency_offset = properties["node.latency-offset-msec"]
  properties["node.latency-offset-msec"] = nil

  -- create the node
  -- it doesn't necessarily need to be a local node,
  -- the other Bluetooth parts run in the local process,
  -- so it's consistent to have also this here
  local node = LocalNode("spa-node-factory", properties)
  node:activate(Feature.Proxy.BOUND)
  parent:store_managed_object(id, node)
  id_to_name_table[id] = properties["node.name"]
  setLatencyOffset(node, latency_offset)
end

function createMonitor()
  local monitor_props = {}
  for k, v in pairs(config.properties or {}) do
    monitor_props[k] = v
  end

  monitor_props["api.glib.mainloop"] = "true"

  local monitor = SpaDevice("api.bluez5.midi.enum", monitor_props)
  if monitor then
    monitor:connect("create-object", createNode)
    monitor:connect("object-removed", function (parent, id)
        node_names_table[id_to_name_table[id]] = nil
        id_to_name_table[id] = nil
    end)
  else
    log:notice("PipeWire's BlueZ MIDI SPA missing or broken. Bluetooth not supported.")
    return nil
  end

  -- reset the name tables to make sure names are recycled
  node_names_table = {}
  id_to_name_table = {}

  monitor:activate(Feature.SpaDevice.ENABLED)
  return monitor
end

function createServers()
  local servers = {}
  local i = 1

  for k, v in pairs(config.servers) do
    local node_props = {
      ["node.name"] = v,
      ["node.description"] = string.format(I18n.gettext("BLE MIDI %d"), i),
      ["api.bluez5.role"] = "server",
      ["factory.name"] = "api.bluez5.midi.node",
      ["api.glib.mainloop"] = "true",
    }
    cutils.evaluateRulesApplyProperties (node_props, "monitor.bluetooth-midi.rules")

    local latency_offset = node_props["node.latency-offset-msec"]
    node_props["node.latency-offset-msec"] = nil

    local node = LocalNode("spa-node-factory", node_props)
    if node then
      node:activate(Feature.Proxy.BOUND)
      table.insert(servers, node)
      setLatencyOffset(node, latency_offset)
    else
      log:notice("Failed to create BLE MIDI server.")
    end
    i = i + 1
  end

  return servers
end

logind_plugin = Plugin.find("logind")
if logind_plugin then
  -- if logind support is enabled, activate
  -- the monitor only when the seat is active
  function startStopMonitor(seat_state)
    log:info(logind_plugin, "Seat state changed: " .. seat_state)

    if seat_state == "active" then
      monitor = createMonitor()
      servers = createServers()
    elseif monitor then
      monitor:deactivate(Feature.SpaDevice.ENABLED)
      monitor = nil
      servers = nil
    end
  end

  logind_plugin:connect("state-changed", function(p, s) startStopMonitor(s) end)
  startStopMonitor(logind_plugin:call("get-state"))
else
  monitor = createMonitor()
  servers = createServers()
end