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|
package internal
import (
"context"
"encoding/json"
"errors"
"expvar"
"fmt"
"os"
"time"
"golang.org/x/oauth2"
)
var (
tokenRefreshCount = expvar.NewInt("gauge_xesite_token_refresh_count")
ErrSecretValueDoesntExist = errors.New("internal: can't find oauth2-token in secret")
)
type cachingTokenSource struct {
base oauth2.TokenSource
filename string
}
func (c *cachingTokenSource) saveToken(tok *oauth2.Token) error {
fout, err := os.Create(c.filename)
if err != nil {
return fmt.Errorf("error creating %s: %w", c.filename, err)
}
defer fout.Close()
return json.NewEncoder(fout).Encode(tok)
}
func ReadToken(fname string) (*oauth2.Token, error) {
fin, err := os.Open(fname)
if err != nil {
return nil, fmt.Errorf("error opening %s: %w", fname, err)
}
defer fin.Close()
var tok oauth2.Token
if err := json.NewDecoder(fin).Decode(&tok); err != nil {
return nil, fmt.Errorf("error decoding %s: %w", fname, err)
}
return &tok, nil
}
func FileExists(filename string) bool {
_, err := os.Stat(filename)
return !os.IsNotExist(err)
}
func (c *cachingTokenSource) loadToken() (*oauth2.Token, error) {
if !FileExists(c.filename) {
return nil, nil
}
return ReadToken(c.filename)
}
func (c *cachingTokenSource) Token() (tok *oauth2.Token, err error) {
tok, _ = c.loadToken()
if tok != nil && tok.Expiry.After(time.Now()) {
return tok, nil
}
if tok, err = c.base.Token(); err != nil {
return nil, err
}
tokenRefreshCount.Add(1)
if err := c.saveToken(tok); err != nil {
return nil, err
}
return tok, err
}
func CachingTokenSource(filename string, config *oauth2.Config, tok *oauth2.Token) oauth2.TokenSource {
orig := config.TokenSource(context.Background(), tok)
return oauth2.ReuseTokenSource(nil, &cachingTokenSource{
filename: filename,
base: orig,
})
}
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