rename lib/{model_context_protocol => mcp}

lib/mcp/prompt.rb

@@ -0,0 +1,82 @@
+# typed: strict
+# frozen_string_literal: true
+
+module MCP
+  class Prompt
+    class << self
+      NOT_SET = Object.new
+
+      attr_reader :description_value
+      attr_reader :arguments_value
+
+      def template(args, server_context:)
+        raise NotImplementedError, "Subclasses must implement template"
+      end
+
+      def to_h
+        { name: name_value, description: description_value, arguments: arguments_value.map(&:to_h) }.compact
+      end
+
+      def inherited(subclass)
+        super
+        subclass.instance_variable_set(:@name_value, nil)
+        subclass.instance_variable_set(:@description_value, nil)
+        subclass.instance_variable_set(:@arguments_value, nil)
+      end
+
+      def prompt_name(value = NOT_SET)
+        if value == NOT_SET
+          @name_value
+        else
+          @name_value = value
+        end
+      end
+
+      def name_value
+        @name_value || StringUtils.handle_from_class_name(name)
+      end
+
+      def description(value = NOT_SET)
+        if value == NOT_SET
+          @description_value
+        else
+          @description_value = value
+        end
+      end
+
+      def arguments(value = NOT_SET)
+        if value == NOT_SET
+          @arguments_value
+        else
+          @arguments_value = value
+        end
+      end
+
+      def define(name: nil, description: nil, arguments: [], &block)
+        Class.new(self) do
+          prompt_name name
+          description description
+          arguments arguments
+          define_singleton_method(:template) do |args, server_context:|
+            instance_exec(args, server_context:, &block)
+          end
+        end
+      end
+
+      def validate_arguments!(args)
+        missing = required_args - args.keys
+        return if missing.empty?
+
+        raise MCP::Server::RequestHandlerError.new(
+          "Missing required arguments: #{missing.join(", ")}", nil, error_type: :missing_required_arguments
+        )
+      end
+
+      private
+
+      def required_args
+        arguments_value.filter_map { |arg| arg.name.to_sym if arg.required }
+      end
+    end
+  end
+end