# Override Hash class with convience methods
class Hash

  # Transform each key in Hash to a symbol. Privately used by non-self method
  def self.transform_keys_to_symbols(value)
    return value if not value.is_a?(Hash)
    hash = value.inject({}){|memo,(k,v)| memo[k.to_sym] = Hash.transform_keys_to_symbols(v); memo}
    return hash
  end

  # Take keys of hash and transform those to a symbols
  def transform_keys_to_symbols
    inject({}){|memo, (k, v)| memo[k.to_sym] = Hash.transform_keys_to_symbols(v); memo}
  end

  # Returns all keys that have a particular value within a nested Hash
  def find_all_values_for(key)
    result = []
    result << self[key]
    self.values.each do |hash_value|
     # next if hash_value.is_a? Array
     #
      if hash_value.is_a?(Array)
        hash_value.each do |array_element|
          result += array_element.find_all_values_for(key) if array_element.is_a? Hash
        end
      end

      values = [hash_value]
      values.each do |value|
        result += value.find_all_values_for(key) if value.is_a? Hash
      end
    end
    result.compact
  end

  # Value present in nested Hash.
  def include_value?(value)
    each_value do |v|
      return true if v == value
      next unless v.is_a? Hash
      v.each_value do |v|
        return true if v == value
        next unless v.is_a? Hash
        v.each_value do |v|
          return true if v == value
        end
      end
    end
    false
  end

  # # Whether key is present at least once
  # def include_key?(key)
  #   result = find_all_values_for key
  #   result != []
  # end

  # Loop through each item within a key within a Hash if the key exists
  # @param [Key] key Key within hash to iterate through
  def each_if_not_null(key)
    case key.class.to_s
    when 'String'
      if self[key]
        self[key].each do |list_item|
          yield(list_item)
        end
      end
    when 'Array', 'Hash'
      if self[key[0]]
        if self[key[0]][key[1]]
          self[key[0]][key[1]].each do |list_item|
            yield(list_item)
          end
        end
      end
    end
  end

end