/*
Copyright 2017 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 util

import (
	"errors"
	"fmt"

	yaml "gopkg.in/yaml.v2"

	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/runtime/serializer"
	clientsetscheme "k8s.io/client-go/kubernetes/scheme"
	kubeadmapiv1alpha1 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
)

// MarshalToYaml marshals an object into yaml.
func MarshalToYaml(obj runtime.Object, gv schema.GroupVersion) ([]byte, error) {
	return MarshalToYamlForCodecs(obj, gv, clientsetscheme.Codecs)
}

// MarshalToYamlForCodecs marshals an object into yaml using the specified codec
// TODO: Is specifying the gv really needed here?
// TODO: Can we support json out of the box easily here?
func MarshalToYamlForCodecs(obj runtime.Object, gv schema.GroupVersion, codecs serializer.CodecFactory) ([]byte, error) {
	mediaType := "application/yaml"
	info, ok := runtime.SerializerInfoForMediaType(codecs.SupportedMediaTypes(), mediaType)
	if !ok {
		return []byte{}, fmt.Errorf("unsupported media type %q", mediaType)
	}

	encoder := codecs.EncoderForVersion(info.Serializer, gv)
	return runtime.Encode(encoder, obj)
}

// UnmarshalFromYaml unmarshals yaml into an object.
func UnmarshalFromYaml(buffer []byte, gv schema.GroupVersion) (runtime.Object, error) {
	return UnmarshalFromYamlForCodecs(buffer, gv, clientsetscheme.Codecs)
}

// UnmarshalFromYamlForCodecs unmarshals yaml into an object using the specified codec
// TODO: Is specifying the gv really needed here?
// TODO: Can we support json out of the box easily here?
func UnmarshalFromYamlForCodecs(buffer []byte, gv schema.GroupVersion, codecs serializer.CodecFactory) (runtime.Object, error) {
	mediaType := "application/yaml"
	info, ok := runtime.SerializerInfoForMediaType(codecs.SupportedMediaTypes(), mediaType)
	if !ok {
		return nil, fmt.Errorf("unsupported media type %q", mediaType)
	}

	decoder := codecs.DecoderToVersion(info.Serializer, gv)
	return runtime.Decode(decoder, buffer)
}

// GroupVersionKindFromBytes parses the bytes and returns the gvk
func GroupVersionKindFromBytes(buffer []byte, codecs serializer.CodecFactory) (schema.GroupVersionKind, error) {

	decoded, err := LoadYAML(buffer)
	if err != nil {
		return schema.EmptyObjectKind.GroupVersionKind(), fmt.Errorf("unable to decode config from bytes: %v", err)
	}
	kindStr, apiVersionStr := "", ""

	// As there was a bug in kubeadm v1.10 and earlier that made the YAML uploaded to the cluster configmap NOT have metav1.TypeMeta information
	// we need to populate this here manually. If kind or apiVersion is empty, we know the apiVersion is v1alpha1, as by the time kubeadm had this bug,
	// it could only write
	// TODO: Remove this "hack" in v1.12 when we know the ConfigMap always contains v1alpha2 content written by kubeadm v1.11. Also, we will drop support for
	// v1alpha1 in v1.12
	kind := decoded["kind"]
	apiVersion := decoded["apiVersion"]
	if kind == nil || len(kind.(string)) == 0 {
		kindStr = "MasterConfiguration"
	} else {
		kindStr = kind.(string)
	}
	if apiVersion == nil || len(apiVersion.(string)) == 0 {
		apiVersionStr = kubeadmapiv1alpha1.SchemeGroupVersion.String()
	} else {
		apiVersionStr = apiVersion.(string)
	}
	gv, err := schema.ParseGroupVersion(apiVersionStr)
	if err != nil {
		return schema.EmptyObjectKind.GroupVersionKind(), fmt.Errorf("unable to parse apiVersion: %v", err)
	}

	return gv.WithKind(kindStr), nil
}

// LoadYAML is a small wrapper around go-yaml that ensures all nested structs are map[string]interface{} instead of map[interface{}]interface{}.
func LoadYAML(bytes []byte) (map[string]interface{}, error) {
	var decoded map[interface{}]interface{}
	if err := yaml.Unmarshal(bytes, &decoded); err != nil {
		return map[string]interface{}{}, fmt.Errorf("couldn't unmarshal YAML: %v", err)
	}

	converted, ok := convert(decoded).(map[string]interface{})
	if !ok {
		return map[string]interface{}{}, errors.New("yaml is not a map")
	}

	return converted, nil
}

// https://stackoverflow.com/questions/40737122/convert-yaml-to-json-without-struct-golang
func convert(i interface{}) interface{} {
	switch x := i.(type) {
	case map[interface{}]interface{}:
		m2 := map[string]interface{}{}
		for k, v := range x {
			m2[k.(string)] = convert(v)
		}
		return m2
	case []interface{}:
		for i, v := range x {
			x[i] = convert(v)
		}
	}
	return i
}