From 150c5c6cb2378709bcb4acae676c4fcf045d6b02 Mon Sep 17 00:00:00 2001
From: Derrick Hammer <derrick@derrickhammer.com>
Date: Sun, 11 Feb 2024 14:58:04 -0500
Subject: [PATCH] feat: add token monitoring and refresh

---
 api/oauth.go | 139 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 136 insertions(+), 3 deletions(-)

diff --git a/api/oauth.go b/api/oauth.go
index db96924..19b706a 100644
--- a/api/oauth.go
+++ b/api/oauth.go
@@ -1,15 +1,22 @@
 package api
 
 import (
+	"code.gitea.io/sdk/gitea"
+	"context"
 	"fmt"
 	"git.lumeweb.com/LumeWeb/gitea-github-proxy/config"
+	"github.com/golang-jwt/jwt"
 	"go.uber.org/zap"
 	"golang.org/x/oauth2"
+	"time"
 )
 
 type oauth struct {
-	cfg    *config.Config
-	logger *zap.Logger
+	cfg              *config.Config
+	logger           *zap.Logger
+	token            *oauth2.Token
+	refresher        oauth2.TokenSource
+	keepAliveRunning bool
 }
 
 func newOauth(cfg *config.Config, logger *zap.Logger) *oauth {
@@ -17,7 +24,7 @@ func newOauth(cfg *config.Config, logger *zap.Logger) *oauth {
 }
 
 func (o oauth) config() *oauth2.Config {
-	return &oauth2.Config{
+	cfg := &oauth2.Config{
 		ClientID:     o.cfg.Oauth.ClientId,
 		ClientSecret: o.cfg.Oauth.ClientSecret,
 		Scopes:       []string{"admin"},
@@ -27,8 +34,134 @@ func (o oauth) config() *oauth2.Config {
 			AuthURL:  fmt.Sprintf("%s/login/oauth/authorize", o.cfg.GiteaUrl),
 		},
 	}
+
+	o.loadToken(cfg)
+	o.keepAlive()
+
+	return cfg
 }
 
 func (o oauth) authUrl() string {
 	return o.config().AuthCodeURL("state")
 }
+
+func (o oauth) loadToken(config *oauth2.Config) {
+	token := &oauth2.Token{}
+
+	if o.cfg.Oauth.Token != "" {
+		o.token = &oauth2.Token{AccessToken: o.cfg.Oauth.Token}
+	}
+
+	if o.cfg.Oauth.RefreshToken != "" {
+		o.token.RefreshToken = o.cfg.Oauth.RefreshToken
+	}
+
+	if o.token != nil {
+		parsedToken, err := jwt.Parse(o.cfg.Oauth.Token, func(token *jwt.Token) (interface{}, error) {
+			return nil, nil
+		})
+
+		if err != nil {
+			o.logger.Fatal("Error parsing token", zap.Error(err))
+		}
+
+		valid := false
+
+		if claims, ok := parsedToken.Claims.(jwt.MapClaims); ok && parsedToken.Valid {
+			if exp, ok := claims["exp"].(float64); ok {
+				expirationTime := time.Unix(int64(exp), 0)
+				if time.Now().Before(expirationTime) {
+					valid = true
+					o.token.Expiry = expirationTime
+				}
+			}
+		}
+
+		if valid {
+			token = o.token
+		} else {
+			o.logger.Info("Token is expired, ignoring")
+		}
+	}
+
+	o.refresher = config.TokenSource(context.Background(), token)
+}
+
+func (o oauth) keepAlive() {
+	if o.cfg.Oauth.Token == "" || o.cfg.Oauth.RefreshToken == "" {
+		o.logger.Error("No token or refresh token provided.")
+		return
+	}
+
+	if o.keepAliveRunning {
+		return
+	}
+
+	ticker := time.NewTicker(30 * time.Minute)
+
+	o.keepAliveRunning = true
+
+	go func() {
+		for {
+			select {
+			case <-ticker.C:
+				if !o.isTokenValid() {
+					if err := o.refreshToken(); err != nil {
+						o.logger.Error("Error refreshing token", zap.Error(err))
+					}
+				}
+			}
+		}
+	}()
+}
+func (o *oauth) isTokenValid() bool {
+	if o.token == nil {
+		return false
+	}
+
+	return o.token.Valid()
+}
+
+func (o *oauth) refreshToken() error {
+	o.logger.Info("Refreshing token...")
+
+	token, err := o.refresher.Token()
+	if err != nil {
+		return err
+	}
+
+	o.token = token
+
+	return nil
+}
+
+func (o *oauth) exchange(code string) (*oauth2.Token, error) {
+	cfg := o.config()
+	token, err := o.config().Exchange(context.Background(), code)
+	if err != nil {
+		return nil, err
+	}
+
+	o.cfg.Oauth.Token = token.AccessToken
+	o.cfg.Oauth.RefreshToken = token.RefreshToken
+	err = config.SaveConfig(o.cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	o.loadToken(cfg)
+	o.keepAlive()
+
+	return token, nil
+}
+
+func (o *oauth) client() *gitea.Client {
+	client, err := getClient(ClientParams{
+		Config: o.cfg,
+	})
+	if err != nil {
+		o.logger.Fatal("Error creating gitea client", zap.Error(err))
+	}
+
+	return client
+}