feat: Add initial implementation of provider (#1)

.gitignore

@@ -9,3 +9,5 @@
 
 # rspec failure tracking
 .rspec_status
+
+Gemfile.lock

.rspec

@@ -1,3 +1,2 @@
---format documentation
 --color
 --require spec_helper

lib/ldclient-openfeature.rb

@@ -1,24 +1,16 @@
 # frozen_string_literal: true
 
+require_relative "ldclient-openfeature/impl/context_converter"
+require_relative "ldclient-openfeature/impl/details_converter"
+require_relative "ldclient-openfeature/provider"
 require_relative "ldclient-openfeature/version"
+
 require "logger"
 
 module LaunchDarkly
   #
   # Namespace for the LaunchDarkly OpenFeature provider.
   #
   module OpenFeature
-    #
-    # @return [Logger] the Rails logger if in Rails, or a default Logger at WARN level otherwise
-    #
-    def self.default_logger
-      if defined?(Rails) && Rails.respond_to?(:logger) && Rails.logger
-        Rails.logger
-      else
-        log = ::Logger.new($stdout)
-        log.level = ::Logger::WARN
-        log
-      end
-    end
   end
 end

lib/ldclient-openfeature/impl/context_converter.rb

@@ -0,0 +1,147 @@
+# frozen_string_literal: true
+
+require 'ldclient-rb'
+require 'open_feature/sdk'
+
+module LaunchDarkly
+  module OpenFeature
+    module Impl
+      class EvaluationContextConverter
+        #
+        # @param logger [Logger]
+        #
+        def initialize(logger)
+          @logger = logger
+        end
+
+        #
+        # Create an LDContext from an EvaluationContext.
+        #
+        # A context will always be created, but the created context may be invalid. Log messages will be written to
+        # indicate the source of the problem.
+        #
+        # @param context [OpenFeature::SDK::EvaluationContext]
+        #
+        # @return [LaunchDarkly::LDContext]
+        #
+        def to_ld_context(context)
+          kind = context.field('kind')
+
+          return build_multi_context(context) if kind == "multi"
+
+          unless kind.nil? || kind.is_a?(String)
+            @logger.warn("'kind' was set to a non-string value; defaulting to user")
+            kind = 'user'
+          end
+
+          targeting_key = context.targeting_key
+          key = context.field('key')
+          targeting_key = get_targeting_key(targeting_key, key)
+
+          kind ||= 'user'
+          build_single_context(context.fields, kind, targeting_key)
+        end
+
+        #
+        # @param targeting_key [String, nil]
+        # @param key [any]
+        #
+        # @return [String]
+        #
+        private def get_targeting_key(targeting_key, key)
+          # The targeting key may be set but empty. So we want to treat an empty string as a not defined one. Later it
+          # could become null, so we will need to check that.
+          if !targeting_key.nil? && targeting_key != "" && key.is_a?(String)
+            # There is both a targeting key and a key. It will work, but probably is not intentional.
+            @logger.warn("EvaluationContext contained both a 'key' and 'targeting_key'.")
+          end
+
+          @logger.warn("A non-string 'key' attribute was provided.") unless key.nil? || key.is_a?(String)
+
+          targeting_key ||= key unless key.nil? || !key.is_a?(String)
+
+          if targeting_key.nil? || targeting_key == "" || !targeting_key.is_a?(String)
+            @logger.error("The EvaluationContext must contain either a 'targeting_key' or a 'key' and the type must be a string.")
+          end
+
+          targeting_key || ""
+        end
+
+        #
+        # @param context [OpenFeature::SDK::EvaluationContext]
+        #
+        # @return [LaunchDarkly::LDContext]
+        #
+        private def build_multi_context(context)
+          contexts = []
+
+          context.fields.each do |kind, attributes|
+            next if kind == 'kind'
+
+            unless attributes.is_a?(Hash)
+              @logger.warn("Top level attributes in a multi-kind context should be dictionaries")
+              next
+            end
+
+            key = attributes.fetch(:key, nil)
+            targeting_key = attributes.fetch(:targeting_key, nil)
+
+            next unless targeting_key.nil? || targeting_key.is_a?(String)
+
+            targeting_key = get_targeting_key(targeting_key, key)
+            single_context = build_single_context(attributes, kind, targeting_key)
+
+            contexts << single_context
+          end
+
+          LaunchDarkly::LDContext.create_multi(contexts)
+        end
+
+        #
+        # @param attributes [Hash]
+        # @param kind [String]
+        # @param key [String]
+        #
+        # @return [LaunchDarkly::LDContext]
+        #
+        private def build_single_context(attributes, kind, key)
+          context = { kind: kind, key: key }
+
+          attributes.each do |k, v|
+            next if %w[key targeting_key kind].include? k
+
+            if k == 'name' && v.is_a?(String)
+              context[:name] = v
+            elsif k == 'name'
+              @logger.error("The attribute 'name' must be a string")
+              next
+            elsif k == 'anonymous' && [true, false].include?(v)
+              context[:anonymous] = v
+            elsif k == 'anonymous'
+              @logger.error("The attribute 'anonymous' must be a boolean")
+              next
+            elsif k == 'privateAttributes' && v.is_a?(Array)
+              private_attributes = []
+              v.each do |private_attribute|
+                unless private_attribute.is_a?(String)
+                  @logger.error("'privateAttributes' must be an array of only string values")
+                  next
+                end
+
+                private_attributes << private_attribute
+              end
+
+              context[:_meta] = { privateAttributes: private_attributes } unless private_attributes.empty?
+            elsif k == 'privateAttributes'
+              @logger.error("The attribute 'privateAttributes' must be an array")
+            else
+              context[k.to_sym] = v
+            end
+          end
+
+          LaunchDarkly::LDContext.create(context)
+        end
+      end
+    end
+  end
+end

lib/ldclient-openfeature/impl/details_converter.rb

@@ -0,0 +1,86 @@
+# frozen_string_literal: true
+
+require 'ldclient-rb'
+require 'open_feature/sdk'
+
+module LaunchDarkly
+  module OpenFeature
+    module Impl
+      class ResolutionDetailsConverter
+        #
+        # @param detail [LaunchDarkly::EvaluationDetail]
+        #
+        # @return [OpenFeature::SDK::ResolutionDetails]
+        #
+        def to_resolution_details(detail)
+          value = detail.value
+          is_default = detail.variation_index.nil?
+          variation_index = detail.variation_index
+
+          reason = detail.reason
+          reason_kind = reason.kind
+
+          openfeature_reason = kind_to_reason(reason_kind)
+
+          openfeature_error_code = nil
+          if reason_kind == LaunchDarkly::EvaluationReason::ERROR
+            openfeature_error_code = error_kind_to_code(reason.error_kind)
+          end
+
+          openfeature_variant = nil
+          openfeature_variant = variation_index.to_s unless is_default
+
+          ::OpenFeature::SDK::Provider::ResolutionDetails.new(
+            value: value,
+            error_code: openfeature_error_code,
+            error_message: nil,
+            reason: openfeature_reason,
+            variant: openfeature_variant
+          )
+        end
+
+        #
+        # @param kind [Symbol]
+        #
+        # @return [String]
+        #
+        private def kind_to_reason(kind)
+          case kind
+          when LaunchDarkly::EvaluationReason::OFF
+            ::OpenFeature::SDK::Provider::Reason::DISABLED
+          when LaunchDarkly::EvaluationReason::TARGET_MATCH
+            ::OpenFeature::SDK::Provider::Reason::TARGETING_MATCH
+          when LaunchDarkly::EvaluationReason::ERROR
+            ::OpenFeature::SDK::Provider::Reason::ERROR
+          else
+            # NOTE: FALLTHROUGH, RULE_MATCH, PREREQUISITE_FAILED intentionally
+            kind.to_s
+          end
+        end
+
+        #
+        # @param error_kind [Symbol]
+        #
+        # @return [String]
+        #
+        private def error_kind_to_code(error_kind)
+          return ::OpenFeature::SDK::Provider::ErrorCode::GENERAL if error_kind.nil?
+
+          case error_kind
+          when LaunchDarkly::EvaluationReason::ERROR_CLIENT_NOT_READY
+            ::OpenFeature::SDK::Provider::ErrorCode::PROVIDER_NOT_READY
+          when LaunchDarkly::EvaluationReason::ERROR_FLAG_NOT_FOUND
+            ::OpenFeature::SDK::Provider::ErrorCode::FLAG_NOT_FOUND
+          when LaunchDarkly::EvaluationReason::ERROR_MALFORMED_FLAG
+            ::OpenFeature::SDK::Provider::ErrorCode::PARSE_ERROR
+          when LaunchDarkly::EvaluationReason::ERROR_USER_NOT_SPECIFIED
+            ::OpenFeature::SDK::Provider::ErrorCode::TARGETING_KEY_MISSING
+          else
+            # NOTE: EXCEPTION_ERROR intentionally omitted
+            ::OpenFeature::SDK::Provider::ErrorCode::GENERAL
+          end
+        end
+      end
+    end
+  end
+end

lib/ldclient-openfeature/provider.rb

@@ -0,0 +1,113 @@
+# frozen_string_literal: true
+
+require 'ldclient-rb'
+require 'open_feature/sdk'
+
+module LaunchDarkly
+  module OpenFeature
+    class Provider
+      attr_reader :metadata
+
+      NUMERIC_TYPES = %i[integer float number].freeze
+      private_constant :NUMERIC_TYPES
+
+      #
+      # @param sdk_key [String]
+      # @param config [LaunchDarkly::Config]
+      # @param wait_for_seconds [Float]
+      #
+      def initialize(sdk_key, config, wait_for_seconds = 5)
+        @client = LaunchDarkly::LDClient.new(sdk_key, config, wait_for_seconds)
+
+        @context_converter = Impl::EvaluationContextConverter.new(config.logger)
+        @details_converter = Impl::ResolutionDetailsConverter.new
+
+        @metadata = ::OpenFeature::SDK::Provider::ProviderMetadata.new(name: "launchdarkly-openfeature-server").freeze
+      end
+
+      def fetch_boolean_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:boolean, flag_key, default_value, evaluation_context)
+      end
+
+      def fetch_string_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:string, flag_key, default_value, evaluation_context)
+      end
+
+      def fetch_number_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:number, flag_key, default_value, evaluation_context)
+      end
+
+      def fetch_integer_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:integer, flag_key, default_value, evaluation_context)
+      end
+
+      def fetch_float_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:float, flag_key, default_value, evaluation_context)
+      end
+
+      def fetch_object_value(flag_key:, default_value:, evaluation_context: nil)
+        resolve_value(:object, flag_key, default_value, evaluation_context)
+      end
+
+      #
+      # @param flag_type [Symbol]
+      # @param flag_key [String]
+      # @param default_value [any]
+      # @param evaluation_context [::OpenFeature::SDK::EvaluationContext, nil]
+      #
+      # @return [::OpenFeature::SDK::Provider::ResolutionDetails]
+      #
+      private def resolve_value(flag_type, flag_key, default_value, evaluation_context)
+        if evaluation_context.nil?
+          return ::OpenFeature::SDK::Provider::ResolutionDetails.new(
+            value: default_value,
+            reason: ::OpenFeature::SDK::Provider::Reason::ERROR,
+            error_code: ::OpenFeature::SDK::Provider::ErrorCode::TARGETING_KEY_MISSING
+          )
+        end
+
+        ld_context = @context_converter.to_ld_context(evaluation_context)
+        evaluation_detail = @client.variation_detail(flag_key, ld_context, default_value)
+
+        if flag_type == :boolean && ![true, false].include?(evaluation_detail.value)
+          return mismatched_type_details(default_value)
+        elsif flag_type == :string && !evaluation_detail.value.is_a?(String)
+          return mismatched_type_details(default_value)
+        elsif NUMERIC_TYPES.include?(flag_type) && !evaluation_detail.value.is_a?(Numeric)
+          return mismatched_type_details(default_value)
+        elsif flag_type == :object && !evaluation_detail.value.is_a?(Hash) && !evaluation_detail.value.is_a?(Array)
+          return mismatched_type_details(default_value)
+        end
+
+        if flag_type == :integer
+          evaluation_detail = LaunchDarkly::EvaluationDetail.new(
+            evaluation_detail.value.to_i,
+            evaluation_detail.variation_index,
+            evaluation_detail.reason
+          )
+        elsif flag_type == :float
+          evaluation_detail = LaunchDarkly::EvaluationDetail.new(
+            evaluation_detail.value.to_f,
+            evaluation_detail.variation_index,
+            evaluation_detail.reason
+          )
+        end
+
+        @details_converter.to_resolution_details(evaluation_detail)
+      end
+
+      #
+      # @param default_value [any]
+      #
+      # @return [::OpenFeature::SDK::Provider::ResolutionDetails]
+      #
+      private def mismatched_type_details(default_value)
+        ::OpenFeature::SDK::Provider::ResolutionDetails.new(
+          value: default_value,
+          reason: ::OpenFeature::SDK::Provider::Reason::ERROR,
+          error_code: ::OpenFeature::SDK::Provider::ErrorCode::TYPE_MISMATCH
+        )
+      end
+    end
+  end
+end