helper.go

package oauth

import (
	"time"

	"github.com/evcc-io/evcc/util"
	"golang.org/x/oauth2"
)

// Refresh refreshes the token every 5m. If token refresh fails 5 times, it is aborted.
func Refresh(log *util.Logger, token *oauth2.Token, ts oauth2.TokenSource, optMaxTokenLifetime ...time.Duration) {
	var failed int

	// limit lifetime of initial token
	limitTokenLife(token, optMaxTokenLifetime...)

	for range time.Tick(5 * time.Minute) {
		// get token- either previous or new
		t, err := ts.Token()
		if err != nil {
			// error means refresh failed
			failed++
			if failed > 5 {
				log.ERROR.Printf("token refresh: %v, giving up", err)
				return
			}

			log.ERROR.Printf("token refresh: %v", err)
			continue
		}

		failed = 0

		// limit lifetime of new tokens
		if t.Expiry != token.Expiry {
			token = t
			limitTokenLife(token, optMaxTokenLifetime...)
		}
	}
}

func limitTokenLife(token *oauth2.Token, optMaxTokenLifetime ...time.Duration) {
	if len(optMaxTokenLifetime) != 1 {
		return
	}

	maxTokenLifetime := optMaxTokenLifetime[0]
	if time.Until(token.Expiry) > maxTokenLifetime {
		token.Expiry = time.Now().Add(maxTokenLifetime)
	}
}