ardour {
    ["type"]    = "EditorAction",
    name        = "Rename regions from markers",
    license     = "MIT",
    author      = "Christopher Arndt",
    description = [[Rename selected regions using track name and label of range marker at region start]]
}

function factory()
    -- there is currently no direct way to find the track
    -- corresponding to a [selected] region
    function find_track_for_region(region_id)
        for route in Session:get_tracks():iter() do
            local track = route:to_track()
            local pl = track:playlist()
            if not pl:region_by_id(region_id):isnil() then
                return track
            end
        end
        assert(0)  -- can't happen, region must be in a playlist
    end

    return function()
        local sel = Editor:get_selection()  -- get current selection
        local loc = Session:locations()     -- get locations

        -- prepare undo operation
        Session:begin_reversible_command("Rename regions from markers")

        -- for each selected region...
        for region in sel.regions:regionlist():iter() do
            -- test if it's an audio region
            local ar = region:to_audioregion()
            if ar:isnil() then
                goto next
            end

            --~ print("Region:", region:name())
            local rid = region:to_stateful():id()
            --~ print("ID:", rid:to_s())

            -- get range marker at region start position
            local pos = region:position()
            local mloc = loc:range_starts_at(pos, Temporal.timecnt_t(0), true)
            if not mloc then
                goto next
            end

            local track = find_track_for_region(rid)

            region:to_stateful():clear_changes()

            --~ print("Marker label:", mloc:name())
            -- rename region to track name + marker label
            region:set_name(track:name() .. " " .. mloc:name())

            -- collect undo data
            Session:add_stateful_diff_command(region:to_statefuldestructible())

            ::next::
        end

        -- all done, commit the combined Undo Operation
        if not Session:abort_empty_reversible_command() then
            Session:commit_reversible_command(nil)
        end
    end
end