feat(libCallApi): implement OAuth2 Option A for remote API auth

README.md

@@ -245,6 +245,27 @@ Input validation helpers.
 ### `libCallApi`
 Utilities for calling external APIs and handling auth/multi-call scenarios.
 
+Remote APIs can authenticate with OAuth2 (`client_credentials`, `refresh_token`, optional `password` grant) or fall back to BasicAuth when `grant-type` is not configured.
+
+Example `param.yaml`:
+
+```yaml
+remoteApis:
+  partner-api:
+    domain: https://api.partner.com
+    name: partner-api
+    auth:
+      grant-type: client_credentials
+      auth-uri: https://auth.partner.com/oauth/token
+      client-id: partner-client
+```
+
+Secure values (existing pattern):
+
+- `remote-api#partner-api#client-secret`
+- `remote-api#partner-api#client-id`
+- `remote-api#partner-api#auth-uri` (alias: `auth-url`)
+
 ### `libCrypto`
 Cryptographic and security primitives.
 

go.mod

@@ -106,6 +106,7 @@ require (
 	golang.org/x/arch v0.20.0 // indirect
 	golang.org/x/crypto v0.41.0 // indirect
 	golang.org/x/net v0.43.0 // indirect
+	golang.org/x/oauth2 v0.36.0 // indirect
 	golang.org/x/sync v0.16.0 // indirect
 	golang.org/x/sys v0.35.0 // indirect
 	golang.org/x/text v0.28.0 // indirect

go.sum

@@ -246,6 +246,8 @@ golang.org/x/mod v0.27.0 h1:kb+q2PyFnEADO2IEF935ehFUXlWiNjJWtRNgBLSfbxQ=
 golang.org/x/mod v0.27.0/go.mod h1:rWI627Fq0DEoudcK+MBkNkCe0EetEaDSwJJkCcjpazc=
 golang.org/x/net v0.43.0 h1:lat02VYK2j4aLzMzecihNvTlJNQUq316m2Mr9rnM6YE=
 golang.org/x/net v0.43.0/go.mod h1:vhO1fvI4dGsIjh73sWfUVjj3N7CA9WkKJNQm2svM6Jg=
+golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
+golang.org/x/oauth2 v0.36.0/go.mod h1:YDBUJMTkDnJS+A4BP4eZBjCqtokkg1hODuPjwiGPO7Q=
 golang.org/x/sync v0.16.0 h1:ycBJEhp9p4vXvUZNszeOq0kGTPghopOL8q0fq3vstxw=
 golang.org/x/sync v0.16.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
 golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

libApplication/init.go

@@ -113,6 +113,13 @@ func InitializeApp[T any](app Application[T]) *App[T] {
 		cache, lock := libCallApi.InitTokenCache()
 		api.TokenCache = cache
 		api.TokenCacheLock = lock
+		if api.AuthData.GrantType != "" {
+			auth, err := libCallApi.NewOAuth2AuthFromAuthData(api.AuthData, libCallApi.NewTokenHTTPClient())
+			if err != nil {
+				log.Fatal("InitializeApp: OAuth2 auth for ", id, "=>", err)
+			}
+			api.Auth = auth
+		}
 		wsParams.RemoteApis[id] = api
 	}
 

libCallApi/auth.go

@@ -1,14 +1,14 @@
 package libCallApi
 
 import (
+	"context"
 	"encoding/base64"
 	"fmt"
 	"sync"
 	"time"
 
 	"github.com/hmmftg/requestCore/libError"
 	"github.com/hmmftg/requestCore/status"
-	"github.com/hmmftg/requestCore/webFramework"
 )
 
 type Auth struct {
@@ -47,7 +47,8 @@ func InitTokenCache() (*TokenCache, *sync.Mutex) {
 }
 
 type AuthSystem interface {
-	Login(w webFramework.WebFramework) (*TokenCache, libError.Error)
+	Login(ctx context.Context) (*TokenCache, libError.Error)
+	Refresh(ctx context.Context, refreshToken string) (*TokenCache, libError.Error)
 }
 
 func (api RemoteApi) GetBasicAuthHeader() string {
@@ -73,19 +74,38 @@ func (api RemoteApi) GetAuthHeader() (string, error) {
 	return fmt.Sprintf("%s %s", api.TokenCache.AccessToken.Type, api.TokenCache.AccessToken.Token), nil
 }
 
-func (api *RemoteApi) handleToken(w webFramework.WebFramework) libError.Error {
+func (api *RemoteApi) handleToken(ctx context.Context) libError.Error {
 	api.TokenCacheLock.Lock()
 	defer api.TokenCacheLock.Unlock()
 
 	if api.TokenCache.AccessToken != nil && !api.TokenCache.Expired() {
-		// another thread handles login before us
 		return nil
 	}
 
+	if api.Auth == nil {
+		return libError.NewWithDescription(
+			status.InternalServerError,
+			"AUTH_SYSTEM_NOT_CONFIGURED",
+			"auth system of api %s is not configured",
+			api.Name,
+		)
+	}
+
+	if api.TokenCache.RefreshToken != nil && api.TokenCache.RefreshToken.Token != "" {
+		tokens, err := api.Auth.Refresh(ctx, api.TokenCache.RefreshToken.Token)
+		if err == nil {
+			api.TokenCache.AccessToken = tokens.AccessToken
+			if tokens.RefreshToken != nil {
+				api.TokenCache.RefreshToken = tokens.RefreshToken
+			}
+			return nil
+		}
+	}
+
 	api.TokenCache.AccessToken = nil
 	api.TokenCache.RefreshToken = nil
 
-	tokens, err := api.Auth.Login(w)
+	tokens, err := api.Auth.Login(ctx)
 	if err != nil {
 		return err
 	}
@@ -94,21 +114,15 @@ func (api *RemoteApi) handleToken(w webFramework.WebFramework) libError.Error {
 	return nil
 }
 
-func (api *RemoteApi) Authenticate(w webFramework.WebFramework) libError.Error {
+func (api *RemoteApi) Authenticate(ctx context.Context) libError.Error {
 	if api.TokenCacheLock == nil {
 		return libError.NewWithDescription(status.InternalServerError, "TOKEN_CACHE_NOT_INITIALIZED", "token cache lock of api %s is null", api.Name)
 	}
-	if api.TokenCache.AccessToken == nil {
-		err := api.handleToken(w)
-		if err != nil {
-			return err
-		}
+	if api.TokenCache == nil {
+		return libError.NewWithDescription(status.InternalServerError, "TOKEN_CACHE_NOT_INITIALIZED", "token cache of api %s is null", api.Name)
 	}
-	if api.TokenCache.Expired() {
-		err := api.handleToken(w)
-		if err != nil {
-			return err
-		}
+	if api.TokenCache.AccessToken == nil || api.TokenCache.Expired() {
+		return api.handleToken(ctx)
 	}
 	return nil
 }

libCallApi/auth_headers.go

@@ -0,0 +1,43 @@
+package libCallApi
+
+import (
+	"context"
+
+	"github.com/hmmftg/requestCore/libError"
+	"github.com/hmmftg/requestCore/status"
+)
+
+func (api *RemoteApi) EnsureAuthorization(ctx context.Context, headers map[string]string) libError.Error {
+	if headers == nil {
+		return libError.NewWithDescription(
+			status.InternalServerError,
+			"AUTH_HEADERS_NIL",
+			"headers map is nil for api %s",
+			api.Name,
+		)
+	}
+	if _, ok := headers["Authorization"]; ok {
+		return nil
+	}
+	if api.Auth != nil {
+		if err := api.Authenticate(ctx); err != nil {
+			return err
+		}
+		authHeader, err := api.GetAuthHeader()
+		if err != nil {
+			return libError.NewWithDescription(
+				status.InternalServerError,
+				"AUTH_HEADER_FAILED",
+				"failed to build auth header for api %s: %v",
+				api.Name,
+				err,
+			)
+		}
+		headers["Authorization"] = authHeader
+		return nil
+	}
+	if api.AuthData.User != "" && api.AuthData.Password != "" {
+		headers["Authorization"] = api.GetBasicAuthHeader()
+	}
+	return nil
+}

libCallApi/auth_test.go

@@ -0,0 +1,191 @@
+package libCallApi_test
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/hmmftg/requestCore/libCallApi"
+	"github.com/hmmftg/requestCore/libError"
+	"gotest.tools/v3/assert"
+)
+
+type countingAuth struct {
+	logins    atomic.Int32
+	refreshes atomic.Int32
+}
+
+func (a *countingAuth) Login(ctx context.Context) (*libCallApi.TokenCache, libError.Error) {
+	a.logins.Add(1)
+	return &libCallApi.TokenCache{
+		AccessToken: &libCallApi.OAuth2Token{
+			Token:      "access-token",
+			Type:       "Bearer",
+			TimeTaken:  time.Now(),
+			ValidUntil: time.Hour,
+		},
+	}, nil
+}
+
+func (a *countingAuth) Refresh(ctx context.Context, refreshToken string) (*libCallApi.TokenCache, libError.Error) {
+	a.refreshes.Add(1)
+	return &libCallApi.TokenCache{
+		AccessToken: &libCallApi.OAuth2Token{
+			Token:      "refreshed-access-token",
+			Type:       "Bearer",
+			TimeTaken:  time.Now(),
+			ValidUntil: time.Hour,
+		},
+	}, nil
+}
+
+func TestAuthenticate_CacheHitAvoidsSecondLogin(t *testing.T) {
+	auth := &countingAuth{}
+	cache, lock := libCallApi.InitTokenCache()
+	api := &libCallApi.RemoteApi{
+		Name:           "test-api",
+		Auth:           auth,
+		TokenCache:     cache,
+		TokenCacheLock: lock,
+	}
+
+	err := api.Authenticate(context.Background())
+	assert.NilError(t, err)
+	err = api.Authenticate(context.Background())
+	assert.NilError(t, err)
+	assert.Equal(t, auth.logins.Load(), int32(1))
+}
+
+func TestAuthenticate_ExpiredTokenTriggersRefresh(t *testing.T) {
+	auth := &countingAuth{}
+	cache, lock := libCallApi.InitTokenCache()
+	cache.AccessToken = &libCallApi.OAuth2Token{
+		Token:      "expired-token",
+		Type:       "Bearer",
+		TimeTaken:  time.Now().Add(-2 * time.Hour),
+		ValidUntil: time.Hour,
+	}
+	cache.RefreshToken = &libCallApi.OAuth2Token{
+		Token:      "refresh-token",
+		TimeTaken:  time.Now(),
+		ValidUntil: time.Hour,
+	}
+	api := &libCallApi.RemoteApi{
+		Name:           "test-api",
+		Auth:           auth,
+		TokenCache:     cache,
+		TokenCacheLock: lock,
+	}
+
+	err := api.Authenticate(context.Background())
+	assert.NilError(t, err)
+	assert.Equal(t, auth.refreshes.Load(), int32(1))
+	assert.Equal(t, auth.logins.Load(), int32(0))
+	assert.Equal(t, api.TokenCache.AccessToken.Token, "refreshed-access-token")
+}
+
+func TestAuthenticate_ConcurrentLoginOnce(t *testing.T) {
+	auth := &countingAuth{}
+	cache, lock := libCallApi.InitTokenCache()
+	api := &libCallApi.RemoteApi{
+		Name:           "test-api",
+		Auth:           auth,
+		TokenCache:     cache,
+		TokenCacheLock: lock,
+	}
+
+	var wg sync.WaitGroup
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			err := api.Authenticate(context.Background())
+			assert.NilError(t, err)
+		}()
+	}
+	wg.Wait()
+	assert.Equal(t, auth.logins.Load(), int32(1))
+}
+
+func TestEnsureAuthorization_PreservesExplicitHeader(t *testing.T) {
+	api := &libCallApi.RemoteApi{
+		Name: "test-api",
+		Auth: &countingAuth{},
+	}
+	headers := map[string]string{
+		"Authorization": "Bearer explicit-token",
+	}
+	err := api.EnsureAuthorization(context.Background(), headers)
+	assert.NilError(t, err)
+	assert.Equal(t, headers["Authorization"], "Bearer explicit-token")
+}
+
+func TestEnsureAuthorization_BasicAuthFallback(t *testing.T) {
+	api := &libCallApi.RemoteApi{
+		Name: "test-api",
+		AuthData: libCallApi.Auth{
+			User:     "user",
+			Password: "pass",
+		},
+	}
+	headers := map[string]string{}
+	err := api.EnsureAuthorization(context.Background(), headers)
+	assert.NilError(t, err)
+	assert.Equal(t, headers["Authorization"], api.GetBasicAuthHeader())
+}
+
+func TestPrepareCall_OAuthAuthorizationHeader(t *testing.T) {
+	var tokenCalls atomic.Int32
+	tokenServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		tokenCalls.Add(1)
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(map[string]any{
+			"access_token": "oauth-access-token",
+			"token_type":   "Bearer",
+			"expires_in":   3600,
+		})
+	}))
+	defer tokenServer.Close()
+
+	apiServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, r.Header.Get("Authorization"), "Bearer oauth-access-token")
+		w.WriteHeader(http.StatusOK)
+		_ = json.NewEncoder(w).Encode(map[string]string{"status": "ok"})
+	}))
+	defer apiServer.Close()
+
+	auth, err := libCallApi.NewOAuth2AuthFromAuthData(libCallApi.Auth{
+		GrantType:    libCallApi.GrantTypeClientCredentials,
+		AuthURI:      tokenServer.URL,
+		ClientID:     "client-id",
+		ClientSecret: "client-secret",
+	}, tokenServer.Client())
+	assert.NilError(t, err)
+
+	cache, lock := libCallApi.InitTokenCache()
+	remoteApi := libCallApi.RemoteApi{
+		Name:           "partner-api",
+		Domain:         apiServer.URL,
+		Auth:           auth,
+		TokenCache:     cache,
+		TokenCacheLock: lock,
+	}
+
+	callData := libCallApi.CallData[map[string]string]{
+		Api:      remoteApi,
+		Path:     "",
+		Method:   http.MethodGet,
+		Headers:  map[string]string{},
+		BodyType: libCallApi.Empty,
+		Context:  context.Background(),
+	}
+
+	req, err := libCallApi.PrepareCall(callData)
+	assert.NilError(t, err)
+	assert.Equal(t, req.Header.Get("Authorization"), "Bearer oauth-access-token")
+}