package main

import (
	"encoding/json"
	"fmt"
	"math/rand"
	"strconv"
	"time"
)

type ID struct {
	StrID  string
	WasInt bool
}

func (id *ID) UnmarshalJSON(data []byte) error {
	var intID int
	err := json.Unmarshal(data, &intID)
	if err == nil {
		*id = ID{strconv.FormatInt(int64(intID), 10), true}
		return nil
	}

	var strID string
	err = json.Unmarshal(data, &strID)
	if err == nil {
		*id = ID{strID, false}
		return nil
	}

	return fmt.Errorf("could not unmarshal %q as an int or string", data)
}

func (id *ID) NewID() string {
	if id.WasInt {
		l := time.Now().UnixNano()
		r := rand.Uint64()
		return fmt.Sprintf("_%d_%d", l, r)
	} else {
		return id.StrID
	}
}