Add dialect support to Type metadata

Closes gh-1344

initializr-docs/src/main/asciidoc/configuration-guide.adoc

@@ -421,8 +421,10 @@ By default, Spring Initializr exposes the following resources (all accessed via
 The build system must be defined with a `build` tag providing the name of the
 `BuildSystem` to use (e.g. `maven`, `gradle`).
 
-Additional tags can be provided to further qualify the entry. Besides the mandatory `build`
-tag, a `format` tag is also available to define the format of the project (e.g. `project`
+Additional tags can be provided to further qualify the entry. If the build system supports
+multiple dialects, the chosen dialect can be specified using the `dialect` tag.
+
+A `format` tag is also available to define the format of the project (e.g. `project`
 for a full project, `build` for just a build file). By default, the HTML UI filters all
 the available types to only display the ones that have a `format` tag with value
 `project`.

initializr-generator-test/src/main/java/io/spring/initializr/generator/test/InitializrMetadataTestBuilder.java

@@ -89,14 +89,14 @@ public InitializrMetadataTestBuilder addBasicDefaults() {
 	}
 
 	public InitializrMetadataTestBuilder addDefaultTypes() {
-		return addType("maven-build", false, "/pom.xml", "maven", "build")
-				.addType("maven-project", true, "/starter.zip", "maven", "project")
-				.addType("gradle-build", false, "/build.gradle", "gradle", "build")
-				.addType("gradle-project", false, "/starter.zip", "gradle", "project");
+		return addType("maven-build", false, "/pom.xml", "maven", null, "build")
+				.addType("maven-project", true, "/starter.zip", "maven", null, "project")
+				.addType("gradle-build", false, "/build.gradle", "gradle", null, "build")
+				.addType("gradle-project", false, "/starter.zip", "gradle", null, "project");
 	}
 
 	public InitializrMetadataTestBuilder addType(String id, boolean defaultValue, String action, String build,
-			String format) {
+			String dialect, String format) {
 		Type type = new Type();
 		type.setId(id);
 		type.setName(id);
@@ -105,6 +105,9 @@ public InitializrMetadataTestBuilder addType(String id, boolean defaultValue, St
 		if (StringUtils.hasText(build)) {
 			type.getTags().put("build", build);
 		}
+		if (StringUtils.hasText(dialect)) {
+			type.getTags().put("dialect", dialect);
+		}
 		if (StringUtils.hasText(format)) {
 			type.getTags().put("format", format);
 		}

initializr-web/src/main/java/io/spring/initializr/web/project/DefaultProjectRequestToDescriptionConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.spring.initializr.web.project;
 
 import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 import io.spring.initializr.generator.buildsystem.BuildSystem;
@@ -165,8 +166,10 @@ private void validateDependencyRange(Version platformVersion, List<Dependency> r
 	}
 
 	private BuildSystem getBuildSystem(ProjectRequest request, InitializrMetadata metadata) {
-		Type typeFromMetadata = metadata.getTypes().get(request.getType());
-		return BuildSystem.forId(typeFromMetadata.getTags().get("build"));
+		Map<String, String> typeTags = metadata.getTypes().get(request.getType()).getTags();
+		String id = typeTags.get("build");
+		String dialect = typeTags.get("dialect");
+		return BuildSystem.forIdAndDialect(id, dialect);
 	}
 
 	private Version getPlatformVersion(ProjectRequest request, InitializrMetadata metadata) {

initializr-web/src/test/java/io/spring/initializr/web/mapper/InitializrMetadataV21JsonMapperTests.java

@@ -44,7 +44,7 @@ class InitializrMetadataV21JsonMapperTests {
 	@Test
 	void withNoAppUrl() throws IOException {
 		InitializrMetadata metadata = new InitializrMetadataTestBuilder()
-				.addType("foo", true, "/foo.zip", "none", "test").addDependencyGroup("foo", "one", "two").build();
+				.addType("foo", true, "/foo.zip", "none", null, "test").addDependencyGroup("foo", "one", "two").build();
 		String json = this.jsonMapper.write(metadata, null);
 		JsonNode result = objectMapper.readTree(json);
 		assertThat(get(result, "_links.foo.href"))
@@ -55,7 +55,7 @@ void withNoAppUrl() throws IOException {
 	@Test
 	void withAppUrl() throws IOException {
 		InitializrMetadata metadata = new InitializrMetadataTestBuilder()
-				.addType("foo", true, "/foo.zip", "none", "test").addDependencyGroup("foo", "one", "two").build();
+				.addType("foo", true, "/foo.zip", "none", null, "test").addDependencyGroup("foo", "one", "two").build();
 		String json = this.jsonMapper.write(metadata, "http://server:8080/my-app");
 		JsonNode result = objectMapper.readTree(json);
 		assertThat(get(result, "_links.foo.href"))

initializr-web/src/test/java/io/spring/initializr/web/project/DefaultProjectRequestToDescriptionConverterTests.java

@@ -68,6 +68,27 @@ void convertWhenTypeDoesNotDefineBuildTagShouldThrowException() {
 				.withMessage("Invalid type 'example-project' (missing build tag) check project metadata");
 	}
 
+	@Test
+	void convertWhenTypeDoesNotDefineDialectTagShouldUseDefaultDialect() {
+		InitializrMetadata metadata = InitializrMetadataTestBuilder.withDefaults()
+				.addType("foo", true, "/foo.zip", GradleBuildSystem.ID, null, "test").build();
+		ProjectRequest request = createProjectRequest();
+		request.setType("foo");
+		assertThat(this.converter.convert(request, metadata).getBuildSystem().dialect())
+				.isEqualTo(GradleBuildSystem.DIALECT_GROOVY);
+	}
+
+	@Test
+	void convertWhenTypeDefinesDialectTagShouldUseDialect() {
+		InitializrMetadata metadata = InitializrMetadataTestBuilder.withDefaults()
+				.addType("foo", true, "/foo.zip", GradleBuildSystem.ID, GradleBuildSystem.DIALECT_KOTLIN, "test")
+				.build();
+		ProjectRequest request = createProjectRequest();
+		request.setType("foo");
+		assertThat(this.converter.convert(request, metadata).getBuildSystem().dialect())
+				.isEqualTo(GradleBuildSystem.DIALECT_KOTLIN);
+	}
+
 	@Test
 	void convertWhenPlatformCompatibilityRangeIsNotSetShouldNotThrowException() {
 		this.metadata = InitializrMetadataTestBuilder.withDefaults().setPlatformCompatibilityRange(null).build();