require 'yaml'
require 'singleton'
require 'active_support/core_ext/hash/indifferent_access'
require 'digest/sha1'

module Waistband
  class Configuration

    include Singleton

    attr_accessor :config_dir, :logger
    attr_writer   :timeout
    attr_reader   :env

    def initialize
      @yml_config = {}
      @indexes    = {}
    end

    def setup
      self.config_dir = default_config_dir unless config_dir

      raise "Please define a valid `config_dir` configuration variable!"  unless config_dir
      raise "Couldn't find configuration directory #{config_dir}"         unless File.exist?(config_dir)

      @env         ||= ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
      yml            = load_yml_with_erb(File.join(config_dir, 'waistband.yml'))
      @yml_config    = yml[@env].with_indifferent_access
      @adapter       = @yml_config.delete('adapter')
    end

    def index(name)
      return @indexes[name] if @indexes[name]
      yml = load_yml_with_erb(File.join(config_dir, "waistband_#{name}.yml"))
      @indexes[name] = yml[@env].with_indifferent_access
    end

    def method_missing(method_name, *args, &block)
      return @yml_config[method_name] if @yml_config.has_key?(method_name)
      super
    end

    def client
      ::Waistband::Client.from_config(client_config_hash)
    end

    def reset_timeout
      remove_instance_variable '@timeout'
    end

    private

      def client_config_hash
        {
          'servers' => servers,
          'randomize_hosts' => true,
          'retry_on_failure' => retries,
          'reload_on_failure' => reload_on_failure,
          'timeout' => timeout,
          'adapter' => @adapter
        }
      end

      def load_yml_with_erb(file)
        if defined?(ERB)
          YAML.safe_load(ERB.new(File.read(file)).result, aliases: true, permitted_classes: [Symbol])
        else
          YAML.safe_load_file(file, aliases: true, permitted_classes: [Symbol])
        end
      end

      def timeout
        return @timeout if defined? @timeout
        @yml_config['timeout']
      end

      def default_config_dir
        @default_config_dir ||= begin
          return nil unless defined?(Rails)
          File.join(Rails.root, 'config')
        end
      end

    # /private

  end
end