email-api-client/client/token.go

package client

import (
	"bytes"
	"encoding/json"
	"errors"
	"gitea.siteworxpro.com/golang-packages/email-api-client/redis"
	"net/http"
	"time"
)

type Token struct {
	AccessToken string `json:"access_token"`
	TokenType   string `json:"token_type"`
	ExpiresIn   uint16 `json:"expires_in"`
}

type AccessTokenRequest struct {
	GrantType    string `json:"grant_type"`
	ClientId     string `json:"client_id"`
	ClientSecret string `json:"client_secret"`
}

func NewToken(config *Configuration) *Token {

	return &Token{}
}

func getToken(configuration *Configuration) (*Token, error) {

	token := FromCache()

	if token != nil && token.AccessToken != "" {
		return token, nil
	}

	request := accessTokenRequest{
		GrantType:    "client_credentials",
		ClientId:     configuration.ClientId,
		ClientSecret: configuration.ClientSecret,
	}

	body, _ := json.Marshal(request)

	resp, err := http.Post(configuration.Endpoint+"/access_token", "application/json", bytes.NewBuffer(body))

	if err != nil {
		return nil, err
	}

	if resp.StatusCode != http.StatusOK {
		return nil, errors.New("Failed to retrieve access token: " + resp.Status)
	}

	token, err = readResponseBody[Token](resp)
	if err != nil {
		return nil, err
	}

	saveCache(token)

	return token, nil
}

func FromCache() *Token {
	rdb, err := redis.NewRedis()

	// Check if Redis connection was successful
	if rdb == nil || err != nil {
		return nil
	}

	token := Token{}

	result, err := rdb.Get("api.access_token").Result()
	if err != nil {
		return &token
	}

	err = json.Unmarshal([]byte(result), &token)
	if err != nil {
		return &token
	}

	return &token
}

func saveCache(token *Token) {
	rdb, err := redis.NewRedis()

	// no cache available
	if rdb == nil || err != nil {
		return
	}

	tokenJson, _ := json.Marshal(token)

	const nanosPerSecond = int64(time.Second)
	expiresIn := time.Duration(int64(token.ExpiresIn) * nanosPerSecond)

	cmd := rdb.Set("api.access_token", tokenJson, expiresIn)
	_, _ = cmd.Result()
}