-- Generates formspec data for the map marker editor
-- selected_id: The id of the currently selected marker, or nil if no marker is
--              selected
-- detail: The map's detail level
--
-- Returns a formspec string for use in containers
function _cartographer.generate_marker_formspec(selected_id, detail)
    local fs = "button[0,0;0.5,0.5;clear_marker;x]";

    if selected_id then
        fs = fs .. string.format("style[marker-%s;bgcolor=blue]", selected_id);
    end

    -- TODO: Support pagination if _cartographer.marker_count is too high
    local i = 0;
    for id in pairs(_cartographer.marker_lookup) do
        fs = fs .. string.format("image_button[%f,%f;0.5,0.5;%s.png;marker-%s;]",
                                i % 5 * 0.5,
                                math.floor(i / 5) * 0.5 + 0.5,
                                cartographer.get_marker_texture(id, detail),
                                id);

        i = i + 1;
    end
    return fs;
end