module Metanorma::Utils

def set_nested_value(hash, keys, new_val)
  key = keys[0]
  if keys.length == 1
    hash[key] = if hash[key].is_a?(::Array) then (hash[key] << new_val)
                else hash[key].nil? ? new_val : [hash[key], new_val]
                end
  elsif hash[key].is_a?(::Array)
    hash[key][-1] = {} if !hash[key].empty? && hash[key][-1].nil?
    hash[key] << {} if hash[key].empty? || !hash[key][-1].is_a?(::Hash)
    set_nested_value(hash[key][-1], keys[1..-1], new_val)
  elsif hash[key].nil? || hash[key].empty?
    hash[key] = {}
    set_nested_value(hash[key], keys[1..-1], new_val)
  elsif hash[key].is_a?(::Hash) && !hash[key][keys[1]]
    set_nested_value(hash[key], keys[1..-1], new_val)
  elsif !hash[key][keys[1]]
    hash[key] = [hash[key], {}]
    set_nested_value(hash[key][-1], keys[1..-1], new_val)
  else
    set_nested_value(hash[key], keys[1..-1], new_val)
  end
  hash
end