// Copyright 2021 Google LLC
//
// 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 kubeconfig

import (
	"github.com/pkg/errors"
	"gopkg.in/yaml.v3"
)

func (k *Kubeconfig) contextsNode() (*yaml.Node, error) {
	contexts := valueOf(k.rootNode, "contexts")
	if contexts == nil {
		return nil, errors.New("\"contexts\" entry is nil")
	} else if contexts.Kind != yaml.SequenceNode {
		return nil, errors.New("\"contexts\" is not a sequence node")
	}
	return contexts, nil
}

func (k *Kubeconfig) contextNode(name string) (*yaml.Node, error) {
	contexts, err := k.contextsNode()
	if err != nil {
		return nil, err
	}

	for _, contextNode := range contexts.Content {
		nameNode := valueOf(contextNode, "name")
		if nameNode.Kind == yaml.ScalarNode && nameNode.Value == name {
			return contextNode, nil
		}
	}
	return nil, errors.Errorf("context with name \"%s\" not found", name)
}

func (k *Kubeconfig) ContextNames() []string {
	contexts := valueOf(k.rootNode, "contexts")
	if contexts == nil {
		return nil
	}
	if contexts.Kind != yaml.SequenceNode {
		return nil
	}

	var ctxNames []string
	for _, ctx := range contexts.Content {
		nameVal := valueOf(ctx, "name")
		if nameVal != nil {
			ctxNames = append(ctxNames, nameVal.Value)
		}
	}
	return ctxNames
}

func (k *Kubeconfig) ContextExists(name string) bool {
	ctxNames := k.ContextNames()
	for _, v := range ctxNames {
		if v == name {
			return true
		}
	}
	return false
}

func valueOf(mapNode *yaml.Node, key string) *yaml.Node {
	if mapNode.Kind != yaml.MappingNode {
		return nil
	}
	for i, ch := range mapNode.Content {
		if i%2 == 0 && ch.Kind == yaml.ScalarNode && ch.Value == key {
			return mapNode.Content[i+1]
		}
	}
	return nil
}