Fix nextLink when host is also provided usecase in annotation processor (#45454)

Author: samvaity

sdk/clientcore/annotation-processor/src/main/java/io/clientcore/annotation/processor/models/HttpRequestContext.java

@@ -55,6 +55,7 @@ public final class HttpRequestContext {
 
     private int[] expectedStatusCodes;
     private TypeMirror defaultExceptionBodyType;
+    private boolean isUriNextLink;
 
     /**
      * Constructs a new HttpRequestContext with default values.
@@ -421,6 +422,24 @@ public TypeMirror getDefaultExceptionBodyType() {
         return defaultExceptionBodyType;
     }
 
+    /**
+     * Sets whether the URI is a {nextlink}.
+     *
+     * @param isUriNextLink true if it is a {nextlink}, false otherwise.
+     */
+    public void setIsUriNextLink(boolean isUriNextLink) {
+        this.isUriNextLink = isUriNextLink;
+    }
+
+    /**
+     * Checks if the URI is a {nextlink}.
+     *
+     * @return true if it is a {nextlink}, false otherwise.
+     */
+    public boolean isUriNextLink() {
+        return isUriNextLink;
+    }
+
     /**
      * Represents a method parameter.
      */

sdk/clientcore/annotation-processor/src/main/java/io/clientcore/annotation/processor/templating/JavaParserTemplateProcessor.java

@@ -352,8 +352,7 @@ void setHttpRequestUri(BlockStmt body, Expression createHttpRequest, HttpRequest
                 .filter(param -> param.getVariableElement().getAnnotation(HostParam.class) != null)
                 .map(HttpRequestContext.MethodParameter::getName)
                 .collect(Collectors.joining(" + "));
-
-            if (CoreUtils.isNullOrEmpty(concatenatedHostParams)) {
+            if (method.isUriNextLink() || CoreUtils.isNullOrEmpty(concatenatedHostParams)) {
                 urlStatement = method.getHost();
             } else {
                 urlStatement = concatenatedHostParams + " + \"/\" + " + method.getHost();

sdk/clientcore/annotation-processor/src/main/java/io/clientcore/annotation/processor/utils/PathBuilder.java

@@ -60,7 +60,18 @@ public static String buildPath(String rawPath, HttpRequestContext method) {
             if (substitution != null) {
                 String substitutionValue
                     = serialize(JsonSerializer.getInstance(), substitution.getParameterVariableName());
-
+                // Special case: if the path is for "{nextLink}", use the variable
+                if (rawPath.contains("{nextLink}")) {
+                    Substitution nextLinkSubstitution = method.getSubstitution("nextLink");
+                    if (nextLinkSubstitution != null) {
+                        // No escaping or concatenation, use the variable name
+                        method.setIsUriNextLink(true);
+                        return nextLinkSubstitution.getParameterVariableName();
+                    } else {
+                        throw new MissingSubstitutionException(
+                            "Could not find substitution for 'nextLink' in method '" + method.getMethodName() + "'");
+                    }
+                }
                 String replacementValue;
                 Optional<HttpRequestContext.MethodParameter> paramOpt = method.getParameters()
                     .stream()

sdk/clientcore/annotation-processor/src/test/java/io/clientcore/annotation/processor/utils/PathBuilderTest.java

@@ -387,4 +387,32 @@ public void buildsPathWithNullQueryParameterValue() {
         String result = PathBuilder.buildPath("https://{endpoint}/keys", context);
         assertEquals("\"https://\" + myEndpoint + \"/keys\"", result);
     }
+
+    @Test
+    public void buildsPathWithNextLinkSpecialCase() {
+        HttpRequestContext context = new HttpRequestContext();
+        context.setMethodName("linkNext");
+        context.addSubstitution(new Substitution("nextLink", "nextLinkVar"));
+        String result = PathBuilder.buildPath("{nextLink}", context);
+        assertEquals("nextLinkVar", result);
+    }
+
+    @Test
+    public void buildsPathWithNextLinkSpecialCaseMissingSubstitution() {
+        HttpRequestContext context = new HttpRequestContext();
+        context.setMethodName("linkNext");
+        MissingSubstitutionException ex
+            = assertThrows(MissingSubstitutionException.class, () -> PathBuilder.buildPath("{nextLink}", context));
+        assertEquals("Could not find substitution for 'nextLink' in method 'linkNext'", ex.getMessage());
+    }
+
+    @Test
+    public void buildsPathWithEndpointAndNextLink() {
+        HttpRequestContext context = new HttpRequestContext();
+        context.setMethodName("linkNext");
+        context.addSubstitution(new Substitution("endpoint", "myEndpoint"));
+        context.addSubstitution(new Substitution("nextLink", "nextLinkVar"));
+        String result = PathBuilder.buildPath("{nextLink}", context);
+        assertEquals("nextLinkVar", result);
+    }
 }