From d4f82bf04d162cd574dd31cdf00bf2d0104357a8 Mon Sep 17 00:00:00 2001
From: Marcos Pereira <marcos.silva@gmail.com>
Date: Fri, 19 Jan 2024 02:49:24 -0500
Subject: [PATCH] kte: Fix parameter declaration for generated templates (#319)

* kte: Fix parameter declaration for generated templates

* Some minor clean ups
---
 .../compiler/kotlin/KotlinCodeGenerator.java  | 31 +++++++++++----
 .../gg/jte/kotlin/TemplateEngineTest.java     | 39 +++++++++++++++++++
 2 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/jte-kotlin/src/main/java/gg/jte/compiler/kotlin/KotlinCodeGenerator.java b/jte-kotlin/src/main/java/gg/jte/compiler/kotlin/KotlinCodeGenerator.java
index 74d381ae..8151ffb2 100644
--- a/jte-kotlin/src/main/java/gg/jte/compiler/kotlin/KotlinCodeGenerator.java
+++ b/jte-kotlin/src/main/java/gg/jte/compiler/kotlin/KotlinCodeGenerator.java
@@ -144,13 +144,7 @@ public void onComplete() {
                 continue;
             }
 
-            kotlinCode.setCurrentTemplateLine(parameter.templateLine);
-            kotlinCode.append("\t\tval ").append(parameter.name).append(" = params[\"").append(parameter.name).append("\"] as ").append(parameter.type);
-            if (parameter.defaultValue != null) {
-                kotlinCode.append("? ?: ");
-                writeCodeWithContentSupport(0, parameter.defaultValue);
-            }
-            kotlinCode.append('\n');
+            writeParameterDeclaration(parameter);
         }
         kotlinCode.append("\t\trender(jteOutput, jteHtmlInterceptor");
 
@@ -184,6 +178,29 @@ public void onComplete() {
         this.classInfo.lineInfo = kotlinCode.getLineInfo();
     }
 
+    private void writeParameterDeclaration(ParamInfo parameter) {
+        var nonNullDefaultValue = parameter.defaultValue != null && !parameter.defaultValue.equals("null");
+
+        kotlinCode.setCurrentTemplateLine(parameter.templateLine);
+        kotlinCode.append("\t\tval ").append(parameter.name).append(" = params[\"").append(parameter.name).append("\"] as ");
+        if (nonNullDefaultValue) {
+            kotlinCode.append(asNullableType(parameter.type));
+            kotlinCode.append(" ?: ");
+            writeCodeWithContentSupport(0, parameter.defaultValue);
+        } else {
+            kotlinCode.append(parameter.type);
+        }
+        kotlinCode.append('\n');
+    }
+
+    private String asNullableType(String type) {
+        if (type.endsWith("?")) {
+            return type;
+        } else {
+            return type + "?";
+        }
+    }
+
     private void addNameField(StringBuilder fields, String name) {
         fields.append("\t@JvmField val ").append(Constants.NAME_FIELD).append(" = \"");
         fields.append(name);
diff --git a/jte-kotlin/src/test/java/gg/jte/kotlin/TemplateEngineTest.java b/jte-kotlin/src/test/java/gg/jte/kotlin/TemplateEngineTest.java
index 7f7433a7..97491128 100644
--- a/jte-kotlin/src/test/java/gg/jte/kotlin/TemplateEngineTest.java
+++ b/jte-kotlin/src/test/java/gg/jte/kotlin/TemplateEngineTest.java
@@ -7,6 +7,10 @@
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.time.LocalDateTime;
 import java.util.*;
 
@@ -764,6 +768,41 @@ void paramWithDefaultValue() {
         assertThat(output.toString()).isEqualTo("Your age is 10");
     }
 
+    @Test
+    void nullableParamsShouldNotHaveDoubleQuestionMarks() throws IOException {
+        givenRawTemplate("@param age: Int? = 10\nYour age is ${age}");
+
+        List<String> compiledPaths = templateEngine.precompileAll();
+        Path classDirectory = Paths.get("jte-classes");
+        var templateContent = Files.readString(classDirectory.resolve(compiledPaths.get(0)));
+
+        assertThat(templateContent).contains("val age = params[\"age\"] as Int?");
+        assertThat(templateContent).doesNotContain("val age = params[\"age\"] as Int??");
+    }
+
+    @Test
+    void nullableParamsWithNonNullDefaultValuesShouldFallbackToTheDefault() throws IOException {
+        givenRawTemplate("@param age: Int? = 10\nYour age is ${age}");
+
+        List<String> compiledPaths = templateEngine.precompileAll();
+        Path classDirectory = Paths.get("jte-classes");
+        var templateContent = Files.readString(classDirectory.resolve(compiledPaths.get(0)));
+
+        assertThat(templateContent).contains("val age = params[\"age\"] as Int? ?: 10");
+    }
+
+    @Test
+    void nullableParamsWithNullDefaultValuesShouldNotUseElvisOperator() throws IOException {
+        givenRawTemplate("@param age: Int? = null\nYour age is ${age}");
+
+        List<String> compiledPaths = templateEngine.precompileAll();
+        Path classDirectory = Paths.get("jte-classes");
+        var templateContent = Files.readString(classDirectory.resolve(compiledPaths.get(0)));
+
+        assertThat(templateContent).contains("val age = params[\"age\"] as Int?");
+        assertThat(templateContent).doesNotContain("val age = params[\"age\"] as Int? ?: null");
+    }
+
     @Test
     void contentParamWithDefaultValue() {
         givenRawTemplate("@param content:gg.jte.Content = @`Some Content`\nThe default content is ${content}");