# frozen_string_literal: true

module DuckDB
  # The DuckDB::Config encapsulates DuckDB Configuration.
  #
  #   require 'duckdb'
  #   config = DuckDB::Config.new
  #   config['default_order'] = 'DESC'
  #   db = DuckDB::Database.open(nil, config)
  #   con = db.connect
  #   con.query('CREATE TABLE numbers (number INTEGER)')
  #   con.query('INSERT INTO numbers VALUES (2), (1), (4), (3)')
  #
  #   # number is ordered by descending.
  #   r = con.query('SELECT number FROM numbers ORDER BY number)
  #   r.first.first # => 4
  class Config
    class << self
      #
      # returns available configuration name and the description.
      # The return value is array object. The first element is the configuration
      # name. The second is the description.
      #
      #   key, desc = DuckDB::Config.key_description(0)
      #   key # => "access_mode"
      #   desc # => "Access mode of the database ([AUTOMATIC], READ_ONLY or READ_WRITE)"
      #
      alias key_description get_config_flag

      #
      # returns the Hash object of all available configuration names and
      # the descriptions.
      #
      # configs = DuckDB::Config.key_descriptions
      # configs['default_order'] # => "The order type used when none is specified ([ASC] or DESC)"
      #
      def key_descriptions
        @key_descriptions ||= (0...size).each_with_object({}) do |i, hash|
          key, description = key_description(i)
          hash[key] = description
        end
      end
    end

    #
    # set configuration value
    #
    #   config = DuckDB::Config.new
    #   # config.set_config('default_order', 'DESC')
    #   config['default_order'] = 'DESC'
    #
    #   db = DuckDB::Database.open(nil, config)
    #   con = db.connect
    #   con.query('CREATE TABLE numbers (number INTEGER)')
    #   con.query('INSERT INTO numbers VALUES (2), (1), (4), (3)')
    #
    #   # numbers are ordered by descending.
    #   r = con.query('SELECT number FROM numbers ORDER BY number)
    #   r.first.first # => 4
    alias []= set_config
  end
end