// Copyright (c) 2018 SAP SE or an SAP affiliate company. All rights reserved. This file is licensed under the Apache Software License, v. 2 except as noted otherwise in the LICENSE file
//
// 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 terraformer

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"

	kutil "github.com/gardener/gardener/pkg/utils/kubernetes"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
)

// Marshal transform RawState to []byte representation. It encodes the raw state data
func (trs *RawState) Marshal() ([]byte, error) {
	return json.Marshal(trs.encodeBase64())
}

// GetRawState returns the conten of terraform state config map
func (t *terraformer) GetRawState(ctx context.Context) (*RawState, error) {
	configMap := &corev1.ConfigMap{}
	if err := t.client.Get(ctx, kutil.Key(t.namespace, t.stateName), configMap); err != nil {
		return nil, err
	}
	return &RawState{
		Data:     configMap.Data[StateKey],
		Encoding: NoneEncoding,
	}, nil
}

// UnmarshalRawState transform passed rawState to RawState struct. It tries to decode the state
func UnmarshalRawState(rawState interface{}) (*RawState, error) {
	var rawData []byte

	switch v := rawState.(type) {
	case *runtime.RawExtension:
		if v == nil {
			rawData = nil
		} else {
			rawData = v.Raw
		}
	case []byte:
		rawData = v
	case string:
		rawData = []byte(v)
	case nil:
		rawData = nil
	default:
		return nil, fmt.Errorf("unsupported type '%T' for unmarshaling Raw Terraform State", rawState)
	}

	terraformStateObj, err := buildRawState(rawData)
	if err != nil {
		return nil, err
	}
	return terraformStateObj.decode()
}

// buildRawState returns RawState from byte slice
func buildRawState(terraformRawState []byte) (*RawState, error) {
	trs := &RawState{}

	if terraformRawState == nil {
		return &RawState{
			Data:     "",
			Encoding: NoneEncoding,
		}, nil
	}

	if err := json.Unmarshal(terraformRawState, trs); err != nil {
		return nil, err
	}
	return trs, nil
}

// encodeBase64 encode the RawState.Data if it is not already base64 encoded
func (trs *RawState) encodeBase64() *RawState {
	if trs.Encoding != Base64Encoding {
		trs.Data = base64.StdEncoding.EncodeToString([]byte(trs.Data))
		trs.Encoding = Base64Encoding
	}
	return trs
}

// decode tries to decode RawState.Data
func (trs *RawState) decode() (*RawState, error) {
	switch trs.Encoding {
	case Base64Encoding:
		trsDec, err := base64.StdEncoding.DecodeString(trs.Data)
		if err != nil {
			return nil, err
		}
		trs.Data = string(trsDec)
		trs.Encoding = NoneEncoding
	case NoneEncoding:
		//do nothing
	default:
		return nil, fmt.Errorf("unrecognised encoding %q for RawState.Data", trs.Encoding)
	}

	return trs, nil
}