feat: [Core] Updated Base Path Behaviour (#219)

Author: MatKuhr

core/src/main/java/com/sap/ai/sdk/core/DestinationResolver.java

@@ -12,6 +12,7 @@
 import com.sap.cloud.sdk.cloudplatform.connectivity.HttpDestination;
 import com.sap.cloud.sdk.cloudplatform.connectivity.ServiceBindingDestinationLoader;
 import com.sap.cloud.sdk.cloudplatform.connectivity.ServiceBindingDestinationOptions;
+import java.net.URI;
 import java.util.List;
 import javax.annotation.Nonnull;
 import lombok.AllArgsConstructor;
@@ -61,9 +62,19 @@ HttpDestination getDestination() {
 
   @Nonnull
   static HttpDestination fromCustomBaseDestination(@Nonnull final HttpDestination destination) {
-    // for custom base destinations we only add the client type header, since users are allowed to
-    // pass a custom base path
-    return addClientTypeHeader(destination);
+    val enhancedBaseDestination = addClientTypeHeader(destination);
+    val path = enhancedBaseDestination.getUri().getPath();
+    if (path == null || path.isEmpty() || path.equals("/")) {
+      return setBasePath(enhancedBaseDestination);
+    }
+    if (path.endsWith("/")) {
+      return enhancedBaseDestination;
+    }
+    val urlWithTrailingSlash = URI.create(enhancedBaseDestination.getUri() + "/");
+
+    return DefaultHttpDestination.fromDestination(enhancedBaseDestination)
+        .uri(urlWithTrailingSlash)
+        .build();
   }
 
   @Nonnull

core/src/test/java/com/sap/ai/sdk/core/AiCoreServiceTest.java

@@ -55,7 +55,7 @@ void testCustomBaseDestination() {
 
     assertThat(customService.getBaseDestination().getUri())
         .hasHost("custom.ai.com")
-        .hasPath("/custom/base/path");
+        .hasPath("/custom/base/path/");
     assertThat(customService.getBaseDestination().getHeaders())
         .describedAs("The client type should be added to ensure its present in all requests")
         .containsExactly(new Header("AI-Client-Type", "AI SDK Java"));

core/src/test/java/com/sap/ai/sdk/core/DestinationResolverTest.java

@@ -7,6 +7,7 @@
 
 import com.sap.cloud.environment.servicebinding.api.ServiceBindingAccessor;
 import com.sap.cloud.environment.servicebinding.api.exception.ServiceBindingAccessException;
+import com.sap.cloud.sdk.cloudplatform.connectivity.DefaultHttpDestination;
 import java.util.List;
 import lombok.val;
 import org.junit.jupiter.api.Test;
@@ -54,4 +55,26 @@ void testNoServiceBindingLoadingThrows() {
     var resolver = new DestinationResolver(mock);
     assertThatThrownBy(resolver::getDestination).isSameAs(exception);
   }
+
+  private record DestinationTestCase(String givenBasePath, String expectedBasePath) {}
+
+  @Test
+  void testFromCustomBaseDestination() {
+    var testCases =
+        new DestinationTestCase[] {
+          new DestinationTestCase("", "/v2/"),
+          new DestinationTestCase("/", "/v2/"),
+          new DestinationTestCase("/foo", "/foo/"),
+          new DestinationTestCase("/foo/", "/foo/")
+        };
+    for (var testCase : testCases) {
+      var url = "https://api.ai.sap" + testCase.givenBasePath;
+      var destination = DefaultHttpDestination.builder(url).build();
+      assertThat(DestinationResolver.fromCustomBaseDestination(destination).getUri().getPath())
+          .describedAs(
+              "Expecting given base path %s to resolve to %s",
+              testCase.givenBasePath, testCase.expectedBasePath)
+          .hasToString(testCase.expectedBasePath);
+    }
+  }
 }