// Package decoder provides common functionality for parsing raw data containing
// K8s resources into structs that can then be applied via the K8s API.
//
// A common use case is reading embedded manifest bundles or manifest files from
// disk (represented as byte[]) and applying them, similar to `kubectl apply`
package decoder

import (
	"bytes"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	yamlutil "k8s.io/apimachinery/pkg/util/yaml"
)

// DecodeYAML decodes data containing a multi-doc YAML file into an array
// of K8s resources, which can be applied to the K8s API via client-go
func DecodeYAML(d []byte) ([]*unstructured.Unstructured, error) {
	var manifests []*unstructured.Unstructured
	// setup decoder for our multidoc YAML file, so we can output individual
	decoder := yamlutil.NewYAMLToJSONDecoder(bytes.NewReader(d))

	for {
		// read a document from our multidoc yaml file
		var rawObj runtime.RawExtension
		if err := decoder.Decode(&rawObj); err != nil {
			break
		}

		// decode using unstructured JSON scheme
		obj := &unstructured.Unstructured{}
		if rawObj.Size() == 0 {
			continue
		}
		if err := obj.UnmarshalJSON(rawObj.Raw); err != nil {
			return nil, err
		}

		// add usable unstructured.Unstructured object to our array of
		// manifests
		manifests = append(manifests, obj)
	}

	return manifests, nil
}