# frozen_string_literal: true

module ElasticAPM
  class Config
    # @api private
    module Options
      # @api private
      class Option
        def initialize(
          key,
          value: nil,
          type: :string,
          default: nil,
          converter: nil
        )
          @key = key
          @type = type
          @default = default
          @converter = converter

          set(value || default)
        end

        attr_reader :key, :value, :default, :type

        def set(value)
          @value = normalize(value)
        end

        def env_key
          "ELASTIC_APM_#{key.upcase}"
        end

        private

        # rubocop:disable Metrics/CyclomaticComplexity, Metrics/MethodLength
        def normalize(val)
          return unless val

          if @converter
            return @converter.call(val)
          end

          case type
          when :string then val.to_s
          when :int then val.to_i
          when :float then val.to_f
          when :bool then normalize_bool(val)
          when :list then normalize_list(val)
          when :dict then normalize_dict(val)
          else
            # raise "Unknown options type '#{type.inspect}'"
            val
          end
        end
        # rubocop:enable Metrics/CyclomaticComplexity, Metrics/MethodLength

        def normalize_bool(val)
          return val unless val.is_a?(String)
          !%w[0 false].include?(val.strip.downcase)
        end

        def normalize_list(val)
          return Array(val) unless val.is_a?(String)
          val.split(/[ ,]/)
        end

        def normalize_dict(val)
          return val unless val.is_a?(String)
          Hash[val.split(/[&,]/).map { |kv| kv.split('=') }]
        end
      end

      # @api private
      module ClassMethods
        def schema
          @schema ||= {}
        end

        def option(*args)
          key = args.shift
          schema[key] = *args
        end
      end

      # @api private
      module InstanceMethods
        def load_schema
          Hash[self.class.schema.map do |key, args|
            [key, Option.new(key, *args)]
          end]
        end

        # rubocop:disable Metrics/MethodLength, Metrics/AbcSize
        def method_missing(name, *value)
          name_str = name.to_s

          if name_str.end_with?('=')
            key = name_str[0...-1].to_sym
            set(key, value.first)

          elsif name_str.end_with?('?')
            key = name_str[0...-1].to_sym
            options.key?(key) ? options[key].value : super

          elsif options.key?(name)
            options.fetch(name).value

          else
            super
          end
        end
        # rubocop:enable Metrics/MethodLength, Metrics/AbcSize

        def [](key)
          options[key]
        end
        alias :get :[]

        def set(key, value)
          options.fetch(key.to_sym).set(value)
        rescue KeyError
          warn format("Unknown option '%s'", key)
          nil
        end
      end

      def self.extended(kls)
        kls.instance_eval { extend ClassMethods }
        kls.class_eval { include InstanceMethods }
      end
    end
  end
end