/*
 *
 * Copyright 2019 gRPC 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 internal contains functions/structs shared by xds
// balancers/resolvers.
package internal

import (
	"encoding/json"
	"fmt"
)

type clientID string

// XDSClientID is the attributes key used to pass the address of the xdsClient
// object shared between the resolver and the balancer. The xdsClient object is
// created by the resolver and passed to the balancer.
const XDSClientID = clientID("xdsClientID")

// LocalityID is xds.Locality without XXX fields, so it can be used as map
// keys.
//
// xds.Locality cannot be map keys because one of the XXX fields is a slice.
type LocalityID struct {
	Region  string `json:"region,omitempty"`
	Zone    string `json:"zone,omitempty"`
	SubZone string `json:"subZone,omitempty"`
}

// ToString generates a string representation of LocalityID by marshalling it into
// json. Not calling it String() so printf won't call it.
func (l LocalityID) ToString() (string, error) {
	b, err := json.Marshal(l)
	if err != nil {
		return "", err
	}
	return string(b), nil
}

// LocalityIDFromString converts a json representation of locality, into a
// LocalityID struct.
func LocalityIDFromString(s string) (ret LocalityID, _ error) {
	err := json.Unmarshal([]byte(s), &ret)
	if err != nil {
		return LocalityID{}, fmt.Errorf("%s is not a well formatted locality ID, error: %v", s, err)
	}
	return ret, nil
}
