openapi v3 basic renderer

Kubernetes-commit: a9c093b16560a9ed50668250fd24889e503f2d8f

pkg/explain/v2/generator.go

@@ -0,0 +1,91 @@
+/*
+Copyright 2022 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v2
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"text/template"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+type TemplateContext struct {
+	GVR       schema.GroupVersionResource
+	Document  map[string]interface{}
+	Recursive bool
+	FieldPath []string
+}
+
+type generator struct {
+	templates map[string]*template.Template
+}
+
+func NewGenerator() *generator {
+	return &generator{
+		templates: make(map[string]*template.Template),
+	}
+}
+
+func (g *generator) AddTemplate(name string, contents string) error {
+	compiled, err := template.
+		New(name).
+		Funcs(map[string]interface{}{
+			"toJson": func(obj any) (string, error) {
+				res, err := json.Marshal(obj)
+				return string(res), err
+			},
+		}).
+		Parse(contents)
+
+	if err != nil {
+		return err
+	}
+
+	g.templates[name] = compiled
+	return nil
+}
+
+func (g *generator) Render(
+	// Template to use for rendering
+	templateName string,
+	// Self-Contained OpenAPI Document Containing all schemas used by $ref
+	// Only OpenAPI V3 documents are supported
+	document map[string]interface{},
+	// Resource within OpenAPI document for which to render explain schema
+	gvr schema.GroupVersionResource,
+	// Field path of child of resource to focus output onto
+	fieldSelector []string,
+	// Boolean indicating whether the fields should be rendered recursively/deeply
+	recursive bool,
+	// Output writer
+	writer io.Writer,
+) error {
+	compiledTemplate, ok := g.templates[templateName]
+	if !ok {
+		return fmt.Errorf("unrecognized format: %s", templateName)
+	}
+
+	err := compiledTemplate.Execute(writer, TemplateContext{
+		Document:  document,
+		Recursive: recursive,
+		FieldPath: fieldSelector,
+		GVR:       gvr,
+	})
+	return err
+}