A lua script to list and switch default sources and sinks

wire.lua

#!/usr/bin/wpexec

Flag_show = nil
Flag_set = nil
Flag_value = nil

function ValidateShowSetFlag(flag)
    if (flag ~= "source") and (flag ~= "sink") then
        print(string.format("invalid flag: %s, supported values are: 'source' and 'sink'", flag))
        os.exit(1)
    end
end

local argv = ...
if argv then
    argv = argv:parse()

    if argv.show ~= nil then
        ValidateShowSetFlag(argv.show)
        Flag_show = argv.show
    end

    if argv.set ~= nil then
        ValidateShowSetFlag(argv.set)
        Flag_set = argv.set
    end

    if argv.value ~= nil then
        Flag_value = argv.value
    end

    if Flag_set ~= nil and Flag_value == nil then
        print("set flag requires a value flag")
        os.exit(1)
    end
end

-- Returns the node with given name
-- Defaults to nil if not found
function FindNodeWithName(om, nodeName, mediaClass)
    local interest = Interest({
        type = "node",
        Constraint({ "node.name", "equals", nodeName }),
        Constraint({
            "media.class", "matches", mediaClass })
    })

    for obj in om:iterate(interest) do
        return obj
    end

    return nil
end

Core.require_api("default-nodes", function(default_nodes)
    obj_mgr = ObjectManager({
        Interest({ type = "client" }),
        Interest({ type = "device" }),
        Interest({ type = "node" }),
    })

    obj_mgr:connect("installed", function(om)
        local function printNode(node)
            local id = node["bound-id"]
            local properties = node.properties
            local global_props = node["global-properties"]

            print(string.format("%s\t%s", properties["node.description"], properties["node.name"]))
        end

        if Flag_show == "sink" then
            local interest = Interest({ type = "node", Constraint({ "media.class", "matches", "*/Sink" }) })
            for obj in om:iterate(interest) do
                printNode(obj)
            end
        end

        if Flag_show == "source" then
            local interest = Interest({ type = "node", Constraint({ "media.class", "matches", "*/Source" }) })
            for obj in om:iterate(interest) do
                printNode(obj)
            end
        end

        if Flag_set == "source" then
            local node = FindNodeWithName(om, Flag_value, "*/Source")

            if node == nil then
                print(string.format("node not found: %s", Flag_value))
            else
                default_nodes:call("set-default-configured-node-name", "Audio/Source", Flag_value)
            end
        end

        if Flag_set == "sink" then
            local node = FindNodeWithName(om, Flag_value, "*/Sink")

            if node == nil then
                print(string.format("node not found: %s", Flag_value))
            else
                default_nodes:call("set-default-configured-node-name", "Audio/Sink", Flag_value)
            end
        end

        Core.quit()
    end)

    obj_mgr:activate()
end)