-- ===================================================================

local nodes_of_interest = {
    "default:lava_flowing"   ,
    "default:lava_source"    ,
    "default:water_flowing"  ,
    "default:water_source"   ,
    "codersea:water_flowing" ,
    "codersea:water_source"  ,
}

local interest_set = ocutil.make_set (nodes_of_interest)

-- ===================================================================

local function is_node_of_interest (uppos)
    local upname = minetest.get_node (uppos).name
    if interest_set [upname] ~= nil then return true end
    return false
end

-- ===================================================================

local function is_air (uppos)
    local upname = minetest.get_node (uppos).name
    if (upname == "air") then
        return true
    end
    return false
end

-- ===================================================================

minetest.register_abm ({
    catch_up  = false             ,
    chance    = 1                 ,
    interval  = 1                 ,
    nodenames = nodes_of_interest ,
    neighbors = { "air"         } ,

    action = function (pos, node)
        if pos.y > 0 then return end
        local uppos
        local newnode = "default:flooddiv"

        local uppos   = { x = pos.x, y = pos.y-1, z = pos.z }
        if is_air (uppos) then
           minetest.add_node (pos, { name = newnode })
           return
        end

        for xi = -1,1 do
            for zi = -1,1 do
                uppos = { x = pos.x+xi, y = pos.y, z = pos.z+zi }
                if is_air (uppos) then
                    minetest.add_node (pos, { name = newnode })
                    return
                end
            end
        end
    end
})

minetest.register_alias ("default:waterdiv" ,
                         "default:flooddiv")