package utils

import (
	"errors"
	"git.bvbej.com/bvbej/base-golang/pkg/hash"
	"git.bvbej.com/bvbej/base-golang/pkg/hmac"
	"git.bvbej.com/bvbej/base-golang/pkg/time_parse"
	"time"
)

var _ UserToken = (*userToken)(nil)

type UserToken interface {
	i()
	Generate(id uint64, platform string) (userID, token string, err error)
	Validate(userID, token, platform string) (id uint64, err error)
}

type userToken struct {
	hashidsSecret string
	hashidsLength int
	hmacSecret    string
	ttl           time.Duration
}

func NewUserToken(hashidsSecret, hmacSecret string, ttl time.Duration) UserToken {
	return &userToken{
		hashidsSecret: hashidsSecret,
		hashidsLength: 32,
		hmacSecret:    hmacSecret,
		ttl:           time.Minute * ttl,
	}
}

func (t *userToken) i() {}

func (t *userToken) Generate(id uint64, platform string) (userID, token string, err error) {
	hashidsPtr := hash.New(t.hashidsSecret, t.hashidsLength)
	userID, err = hashidsPtr.HashidsEncode([]int{int(int64(id)), int(time.Now().Unix())})
	if err != nil {
		return "", "", err
	}
	hmacPtr := hmac.New(t.hmacSecret)
	token = hmacPtr.Sha256ToString(userID + platform)
	return
}

func (t *userToken) Validate(userID, token, platform string) (id uint64, err error) {
	hashidsPtr := hash.New(t.hashidsSecret, t.hashidsLength)
	hmacPtr := hmac.New(t.hmacSecret)
	if hmacPtr.Sha256ToString(userID+platform) != token {
		return id, errors.New("token invalid")
	}
	hashidsDecode, err := hashidsPtr.HashidsDecode(userID)
	if err != nil {
		return id, err
	}
	if len(hashidsDecode) == 2 {
		if time_parse.SubInLocation(time.Unix(int64(hashidsDecode[1]), 0)) > float64(t.ttl/time.Second) {
			return id, errors.New("token expired")
		}
	}
	return uint64(hashidsDecode[0]), nil
}