module API
  module OpenAPI
    extend self

    def spec(version: :stable)
      spec_path = Rails.application.root.join("docs/api/apiv3/openapi-spec.yml")

      if spec_path.exist?
        assemble_spec spec_path
      else
        API::OpenAPI::BlueprintImport.convert version: version, single_file: true
      end
    end

    def assemble_spec(file_path)
      spec = YAML.load File.read(file_path.to_s)

      substitute_refs(spec, path: file_path.parent, root_path: file_path.parent)
    end

    def substitute_refs(spec, path:, root_path:, root_spec: spec)
      if spec.is_a?(Hash)
        if spec.size == 1 && spec.keys.first == "$ref"
          ref_path = path.join spec.values.first
          ref_value = YAML.load File.read(ref_path.to_s)

          resolve_refs ref_value, path: ref_path.parent, root_path: root_path, root_spec: root_spec
        else
          spec.map { |k, v| [k, substitute_refs(v, path: path, root_path: root_path, root_spec: root_spec)] }.to_h
        end
      elsif spec.is_a?(Array)
        spec.map { |s| substitute_refs s, path: path, root_path: root_path, root_spec: root_spec }
      else
        spec
      end
    end

    def resolve_refs(spec, path:, root_path:, root_spec:)
      if spec.is_a?(Hash)
        if spec.size == 1 && spec.keys.first == "$ref"
          ref_path = spec.values.first

          if ref_path.start_with?(".")
            schema_file = path.join(ref_path).to_s.sub(root_path.to_s, ".")
            schema_path = path.join(ref_path).parent.to_s.sub(root_path.to_s, "").split("/").drop(1)
            schema_name = root_spec.dig(*schema_path).find { |k, v| v["$ref"] == schema_file }.first
            schema_ref = path.join(ref_path).parent.join(schema_name).to_s.sub(root_path.to_s, "#")

            { spec.keys.first => schema_ref }
          else
            spec
          end
        else
          spec.map { |k, v| [k, resolve_refs(v, path: path, root_path: root_path, root_spec: root_spec)] }.to_h
        end
      elsif spec.is_a?(Array)
        spec.map { |v| resolve_refs(v, path: path, root_path: root_path, root_spec: root_spec) }
      else
        spec
      end
    end
  end
end