/*
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 config

import (
	"encoding/json"
	"strings"

	"github.com/ghodss/yaml"
	"github.com/go-openapi/spec"
	"github.com/pkg/errors"
	"k8s.io/kube-openapi/pkg/common"
	"sigs.k8s.io/kustomize/pkg/gvk"
	"sigs.k8s.io/kustomize/pkg/ifc"
)

type myProperties map[string]spec.Schema
type nameToApiMap map[string]common.OpenAPIDefinition

// LoadConfigFromCRDs parse CRD schemas from paths into a TransformerConfig
func LoadConfigFromCRDs(
	ldr ifc.Loader, paths []string) (*TransformerConfig, error) {
	tc := MakeEmptyConfig()
	for _, path := range paths {
		content, err := ldr.Load(path)
		if err != nil {
			return nil, err
		}
		m, err := makeNameToApiMap(content)
		if err != nil {
			return nil, errors.Wrapf(err, "unable to parse open API definition from '%s'", path)
		}
		otherTc, err := makeConfigFromApiMap(m)
		if err != nil {
			return nil, err
		}
		tc, err = tc.Merge(otherTc)
		if err != nil {
			return nil, err
		}
	}
	return tc, nil
}

func makeNameToApiMap(content []byte) (result nameToApiMap, err error) {
	if content[0] == '{' {
		err = json.Unmarshal(content, &result)
	} else {
		err = yaml.Unmarshal(content, &result)
	}
	return
}

func makeConfigFromApiMap(m nameToApiMap) (*TransformerConfig, error) {
	result := MakeEmptyConfig()
	for name, api := range m {
		if !looksLikeAk8sType(api.Schema.SchemaProps.Properties) {
			continue
		}
		tc := MakeEmptyConfig()
		err := loadCrdIntoConfig(
			tc, makeGvkFromTypeName(name), m, name, []string{})
		if err != nil {
			return result, err
		}
		result, err = result.Merge(tc)
		if err != nil {
			return result, err
		}
	}
	return result, nil
}

// TODO: Get Group and Version for CRD from the
// openAPI definition once
// "x-kubernetes-group-version-kind" is available in CRD
func makeGvkFromTypeName(n string) gvk.Gvk {
	names := strings.Split(n, ".")
	kind := names[len(names)-1]
	return gvk.Gvk{Kind: kind}
}

func looksLikeAk8sType(properties myProperties) bool {
	_, ok := properties["kind"]
	if !ok {
		return false
	}
	_, ok = properties["apiVersion"]
	if !ok {
		return false
	}
	_, ok = properties["metadata"]
	if !ok {
		return false
	}
	return true
}

const (
	// "x-kubernetes-annotation": ""
	xAnnotation = "x-kubernetes-annotation"

	// "x-kubernetes-label-selector": ""
	xLabelSelector = "x-kubernetes-label-selector"

	// "x-kubernetes-identity": ""
	xIdentity = "x-kubernetes-identity"

	// "x-kubernetes-object-ref-api-version": <apiVersion name>
	xVersion = "x-kubernetes-object-ref-api-version"

	// "x-kubernetes-object-ref-kind": <kind name>
	xKind = "x-kubernetes-object-ref-kind"

	// "x-kubernetes-object-ref-name-key": "name"
	// default is "name"
	xNameKey = "x-kubernetes-object-ref-name-key"
)

// loadCrdIntoConfig loads a CRD spec into a TransformerConfig
func loadCrdIntoConfig(
	theConfig *TransformerConfig, theGvk gvk.Gvk, theMap nameToApiMap,
	typeName string, path []string) (err error) {
	api, ok := theMap[typeName]
	if !ok {
		return nil
	}
	for propName, property := range api.Schema.SchemaProps.Properties {
		_, annotate := property.Extensions.GetString(xAnnotation)
		if annotate {
			err = theConfig.AddAnnotationFieldSpec(
				makeFs(theGvk, append(path, propName)))
			if err != nil {
				return
			}
		}
		_, label := property.Extensions.GetString(xLabelSelector)
		if label {
			err = theConfig.AddLabelFieldSpec(
				makeFs(theGvk, append(path, propName)))
			if err != nil {
				return
			}
		}
		_, identity := property.Extensions.GetString(xIdentity)
		if identity {
			err = theConfig.AddPrefixFieldSpec(
				makeFs(theGvk, append(path, propName)))
			if err != nil {
				return
			}
		}
		version, ok := property.Extensions.GetString(xVersion)
		if ok {
			kind, ok := property.Extensions.GetString(xKind)
			if ok {
				nameKey, ok := property.Extensions.GetString(xNameKey)
				if !ok {
					nameKey = "name"
				}
				err = theConfig.AddNamereferenceFieldSpec(
					NameBackReferences{
						Gvk: gvk.Gvk{Kind: kind, Version: version},
						FieldSpecs: []FieldSpec{
							makeFs(theGvk, append(path, propName, nameKey))},
					})
				if err != nil {
					return
				}
			}
		}
		if property.Ref.GetURL() != nil {
			loadCrdIntoConfig(
				theConfig, theGvk, theMap,
				property.Ref.String(), append(path, propName))
		}
	}
	return nil
}

func makeFs(in gvk.Gvk, path []string) FieldSpec {
	return FieldSpec{
		CreateIfNotPresent: false,
		Gvk:                in,
		Path:               strings.Join(path, "/"),
	}
}