/*
Copyright 2018 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 transformers

import (
	"errors"
	"fmt"

	"sigs.k8s.io/kustomize/pkg/gvk"
	"sigs.k8s.io/kustomize/pkg/resmap"
	"sigs.k8s.io/kustomize/pkg/transformers/config"
)

// namePrefixTransformer contains the prefix and the FieldSpecs
// for each field needing a name prefix.
type namePrefixTransformer struct {
	prefix           string
	fieldSpecsToUse  []config.FieldSpec
	fieldSpecsToSkip []config.FieldSpec
}

var _ Transformer = &namePrefixTransformer{}

var prefixFieldSpecsToSkip = []config.FieldSpec{
	{
		Gvk: gvk.Gvk{Kind: "CustomResourceDefinition"},
	},
	{
		Gvk: gvk.Gvk{Kind: "Namespace"},
	},
}

// NewNamePrefixTransformer construct a namePrefixTransformer.
func NewNamePrefixTransformer(np string, pc []config.FieldSpec) (Transformer, error) {
	if len(np) == 0 {
		return NewNoOpTransformer(), nil
	}
	if pc == nil {
		return nil, errors.New("fieldSpecs is not expected to be nil")
	}
	return &namePrefixTransformer{fieldSpecsToUse: pc, prefix: np, fieldSpecsToSkip: prefixFieldSpecsToSkip}, nil
}

// Transform prepends the name prefix.
func (o *namePrefixTransformer) Transform(m resmap.ResMap) error {
	mf := resmap.ResMap{}

	for id := range m {
		found := false
		for _, path := range o.fieldSpecsToSkip {
			if id.Gvk().IsSelected(&path.Gvk) {
				found = true
				break
			}
		}
		if !found {
			mf[id] = m[id]
			delete(m, id)
		}
	}

	for id := range mf {
		objMap := mf[id].Map()
		for _, path := range o.fieldSpecsToUse {
			if !id.Gvk().IsSelected(&path.Gvk) {
				continue
			}
			err := mutateField(objMap, path.PathSlice(), path.CreateIfNotPresent, o.addPrefix)
			if err != nil {
				return err
			}
			newId := id.CopyWithNewPrefix(o.prefix)
			m[newId] = mf[id]
		}
	}
	return nil
}

func (o *namePrefixTransformer) addPrefix(in interface{}) (interface{}, error) {
	s, ok := in.(string)
	if !ok {
		return nil, fmt.Errorf("%#v is expectd to be %T", in, s)
	}
	return o.prefix + s, nil
}