feat(java-sdk): configurable token endpoint (#240)

Author: rhamzeh

.gitignore

@@ -8,3 +8,7 @@ docs/openapi/*.json-e
 .dccache
 
 clients/**/*
+
+# JetBrains IDEs
+.idea/
+*.iml

config/clients/java/template/creds-OAuth2Client.java.mustache

@@ -7,30 +7,27 @@ import {{configPackage}}.*;
 import {{errorsPackage}}.ApiException;
 import {{errorsPackage}}.FgaInvalidParameterException;
 import java.io.IOException;
-import java.net.HttpURLConnection;
-import java.net.http.HttpClient;
+import java.net.URI;
 import java.net.http.HttpRequest;
-import java.net.http.HttpResponse;
 import java.time.Instant;
 import java.util.concurrent.CompletableFuture;
 
 public class OAuth2Client {
+    public static final String DEFAULT_TOKEN_ENDPOINT_PATH = "/oauth/token";
     private final ApiClient apiClient;
-    private final Credentials credentials;
     private final AccessToken token = new AccessToken();
     private final CredentialsFlowRequest authRequest;
-    private final String apiTokenIssuer;
+    private final String tokenEndpointUrl;
 
     /**
      * Initializes a new instance of the {@link OAuth2Client} class
      *
      * @param configuration Configuration, including credentials, that can be used to retrieve an access tokens
      */
-    public OAuth2Client(Configuration configuration, ApiClient apiClient) throws FgaInvalidParameterException {
-        this.credentials = configuration.getCredentials();
-
+    public OAuth2Client(Configuration configuration, ApiClient apiClient) {
+        Credentials credentials = configuration.getCredentials();
         this.apiClient = apiClient;
-        this.apiTokenIssuer = credentials.getClientCredentials().getApiTokenIssuer();
+        this.tokenEndpointUrl = buildTokenEndpointUrl(credentials.getClientCredentials().getApiTokenIssuer());
         this.authRequest = new CredentialsFlowRequest();
         this.authRequest.setClientId(credentials.getClientCredentials().getClientId());
         this.authRequest.setClientSecret(credentials.getClientCredentials().getClientSecret());
@@ -65,10 +62,11 @@ public class OAuth2Client {
         try {
             byte[] body = apiClient.getObjectMapper().writeValueAsBytes(authRequest);
 
-            Configuration config = new Configuration().apiUrl("https://" + apiTokenIssuer);
+            Configuration config = new Configuration().apiUrl(tokenEndpointUrl);
+
+            HttpRequest.Builder requestBuilder = ApiClient.requestBuilder("POST", "", body, config);
 
-            HttpRequest request = ApiClient.requestBuilder("POST", "/oauth/token", body, config)
-                    .build();
+            HttpRequest request = requestBuilder.build();
 
             return new HttpRequestAttempt<>(request, "exchangeToken", CredentialsFlowResponse.class, apiClient, config)
                     .attemptHttpRequest()
@@ -77,4 +75,18 @@ public class OAuth2Client {
             throw new ApiException(e);
         }
     }
+
+    private static String buildTokenEndpointUrl(String issuer) {
+        var uri = URI.create(issuer);
+
+        if (uri.getScheme() == null) {
+            uri = URI.create("https://" + issuer);
+        }
+
+        if (uri.getPath().isEmpty() || uri.getPath().equals("/")) {
+            uri = URI.create(uri.getScheme() + "://" + uri.getAuthority() + DEFAULT_TOKEN_ENDPOINT_PATH);
+        }
+
+        return uri.toString();
+    }
 }

config/clients/java/template/creds-OAuth2ClientTest.java.mustache

@@ -9,26 +9,56 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.pgssoft.httpclient.HttpClientMock;
 import {{clientPackage}}.ApiClient;
 import {{configPackage}}.*;
-import {{errorsPackage}}.FgaInvalidParameterException;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.stream.Stream;
+
 
 class OAuth2ClientTest {
     private static final String CLIENT_ID = "client";
     private static final String CLIENT_SECRET = "secret";
     private static final String AUDIENCE = "audience";
     private static final String GRANT_TYPE = "client_credentials";
-    private static final String API_TOKEN_ISSUER = "test.fga.dev";
-    private static final String POST_URL = "https://" + API_TOKEN_ISSUER + "/oauth/token";
     private static final String ACCESS_TOKEN = "0123456789";
 
     private final ObjectMapper mapper = new ObjectMapper();
     private HttpClientMock mockHttpClient;
 
-    private OAuth2Client oAuth2;
+    private static Stream<Arguments> issuersTokenEndpoint() {
+        return Stream.of(
+                Arguments.of("issuer.fga.example", "https://issuer.fga.example/oauth/token"),
+                Arguments.of("https://issuer.fga.example", "https://issuer.fga.example/oauth/token"),
+                Arguments.of("https://issuer.fga.example/", "https://issuer.fga.example/oauth/token"),
+                Arguments.of("https://issuer.fga.example:8080", "https://issuer.fga.example:8080/oauth/token"),
+                Arguments.of("https://issuer.fga.example:8080/", "https://issuer.fga.example:8080/oauth/token"),
+                Arguments.of("issuer.fga.example/some_endpoint", "https://issuer.fga.example/some_endpoint"),
+                Arguments.of("https://issuer.fga.example/some_endpoint", "https://issuer.fga.example/some_endpoint"),
+                Arguments.of("https://issuer.fga.example:8080/some_endpoint", "https://issuer.fga.example:8080/some_endpoint")
+        );
+    }
 
-    @BeforeEach
-    public void setup() throws FgaInvalidParameterException {
+    @ParameterizedTest
+    @MethodSource("issuersTokenEndpoint")
+    public void exchangeToken(String apiTokenIssuer, String tokenEndpointUrl) throws Exception {
+        // Given
+        OAuth2Client oAuth2 = configureClient(apiTokenIssuer);
+        String expectedPostBody = String.format(
+                "{\"client_id\":\"%s\",\"client_secret\":\"%s\",\"audience\":\"%s\",\"grant_type\":\"%s\"}",
+                CLIENT_ID, CLIENT_SECRET, AUDIENCE, GRANT_TYPE);
+        String responseBody = String.format("{\"access_token\":\"%s\"}", ACCESS_TOKEN);
+        mockHttpClient.onPost(tokenEndpointUrl).withBody(is(expectedPostBody)).doReturn(200, responseBody);
+
+        // When
+        String result = oAuth2.getAccessToken().get();
+
+        // Then
+        mockHttpClient.verify().post(tokenEndpointUrl).withBody(is(expectedPostBody)).called();
+        assertEquals(ACCESS_TOKEN, result);
+    }
+
+    private OAuth2Client configureClient(String apiTokenIssuer) {
         System.setProperty("HttpRequestAttempt.debug-logging", "enable");
 
         mockHttpClient = new HttpClientMock();
@@ -38,31 +68,14 @@ class OAuth2ClientTest {
                 .clientId(CLIENT_ID)
                 .clientSecret(CLIENT_SECRET)
                 .apiAudience(AUDIENCE)
-                .apiTokenIssuer(API_TOKEN_ISSUER));
+                .apiTokenIssuer(apiTokenIssuer));
 
         var configuration = new Configuration().apiUrl("").credentials(credentials);
 
         var apiClient = mock(ApiClient.class);
         when(apiClient.getHttpClient()).thenReturn(mockHttpClient);
         when(apiClient.getObjectMapper()).thenReturn(mapper);
 
-        oAuth2 = new OAuth2Client(configuration, apiClient);
-    }
-
-    @Test
-    public void exchangeToken() throws Exception {
-        // Given
-        String expectedPostBody = String.format(
-                "{\"client_id\":\"%s\",\"client_secret\":\"%s\",\"audience\":\"%s\",\"grant_type\":\"%s\"}",
-                CLIENT_ID, CLIENT_SECRET, AUDIENCE, GRANT_TYPE);
-        String responseBody = String.format("{\"access_token\":\"%s\"}", ACCESS_TOKEN);
-        mockHttpClient.onPost(POST_URL).withBody(is(expectedPostBody)).doReturn(200, responseBody);
-
-        // When
-        String result = oAuth2.getAccessToken().get();
-
-        // Then
-        mockHttpClient.verify().post(POST_URL).withBody(is(expectedPostBody)).called();
-        assertEquals(ACCESS_TOKEN, result);
+        return new OAuth2Client(configuration, apiClient);
     }
 }