Add proper support for multi-project builds (#23)

Author: EtienneMiret

README.md

@@ -115,7 +115,10 @@ plugin and its `jar` task.
 
 ### In a multi-projects build
 
-You can apply this plugin to several subprojects of a multi-projects build.
+You can apply this plugin to a multi-projects build.
+If only one subproject need it, just apply it to said subproject.
+Otherwise, apply it to the root project,
+or to a common ancestor of all subprojects that need it.
 See [samples/multi-projects](samples/multi-projects/build.gradle).
 
 ### Watching for changes

samples/multi-projects/build.gradle

@@ -1,3 +1,15 @@
+/*
+ * In case several subprojects need this plugin, it is recommended to apply and
+ * configure it on the root project. For one, it allows you to share
+ * the sass version (among other configuration). For another, it will save
+ * disk space as dart-sass will be installed once per project where this plugin
+ * is applied.
+ */
 plugins {
-  id 'io.miret.etienne.sass' version '1.4.2' apply false
+  id 'io.miret.etienne.sass' version '1.4.2'
+}
+
+sass {
+  version = "1.54.4"
+  // Your customization here
 }

samples/multi-projects/subproject-a/build.gradle

@@ -1,4 +1,8 @@
+/* Don't reapply this plugin on subprojects if already done in root project. */
 plugins {
   id 'war'
-  id 'io.miret.etienne.sass'
+}
+
+compileSass {
+  // Configuration for this subproject "compileSass" task.
 }

samples/multi-projects/subproject-b/build.gradle

@@ -1,4 +1,8 @@
+/* Don't reapply this plugin on subprojects if already done in root project. */
 plugins {
   id 'war'
-  id 'io.miret.etienne.sass'
+}
+
+compileSass {
+  // Configuration for this subproject "compileSass" task.
 }

src/functionalTest/resources/io/miret/etienne/gradle/sass/multi-project/app/build.gradle

@@ -1,8 +0,0 @@
-plugins {
-  id 'io.miret.etienne.sass'
-}
-
-sass {
-  version = '42.0'
-  baseUrl = System.getenv("URL")
-}

src/functionalTest/resources/io/miret/etienne/gradle/sass/multi-project/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+  id 'io.miret.etienne.sass'
+}
+
+sass {
+  version = '42.0'
+  baseUrl = System.getenv("URL")
+}

src/functionalTest/resources/io/miret/etienne/gradle/sass/multi-project/lib/build.gradle

@@ -1,8 +0,0 @@
-plugins {
-  id 'io.miret.etienne.sass'
-}
-
-sass {
-  version = '42.0'
-  baseUrl = System.getenv("URL")
-}

src/main/java/io/miret/etienne/gradle/sass/CompileSass.java

@@ -4,6 +4,7 @@
 import lombok.Setter;
 import org.apache.tools.ant.taskdefs.condition.Os;
 import org.gradle.api.DefaultTask;
+import org.gradle.api.Project;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.tasks.*;
 import org.gradle.workers.WorkQueue;
@@ -86,10 +87,7 @@ public FileCollection getInputFiles () {
   @InputFile
   public File getExecutable () {
     String command = Os.isFamily (Os.FAMILY_WINDOWS) ? "sass.bat" : "sass";
-    SassGradlePluginExtension sassExtension = getProject ()
-        .getExtensions ()
-        .findByType (SassGradlePluginExtension.class);
-    assert sassExtension != null;
+    SassGradlePluginExtension sassExtension = findExtension();
     return sassExtension.getDirectory ()
         .toPath ()
         .resolve (sassExtension.getVersion ())
@@ -98,6 +96,22 @@ public File getExecutable () {
         .toFile ();
   }
 
+  private SassGradlePluginExtension findExtension() {
+    Project project = getProject();
+    SassGradlePluginExtension extension = null;
+    while (extension == null && project != null) {
+      extension = project.getExtensions()
+          .findByType(SassGradlePluginExtension.class);
+      project = project.getParent();
+    }
+    if (extension == null) {
+      throw new IllegalStateException(
+          "SassGradlePluginExtension wasn't registered in any parent project."
+      );
+    }
+    return extension;
+  }
+
   public void loadPath (File loadPath) {
     loadPaths.add (loadPath);
   }

src/main/java/io/miret/etienne/gradle/sass/SassGradlePlugin.java

@@ -43,6 +43,14 @@ public void apply (Project project) {
           task.from (downloadedFiles);
           task.into (new File (extension.getDirectory (), extension.getVersion ()));
         });
+    compileSass(project, extension, installSass);
+  }
+
+  private void compileSass(
+      Project project,
+      SassGradlePluginExtension extension,
+      TaskProvider<?> installSass
+  ) {
     TaskProvider<CompileSass> compileSass = project.getTasks ()
         .register ("compileSass", CompileSass.class, task -> {
           task.setDescription ("Compile sass and scss.");
@@ -56,6 +64,9 @@ public void apply (Project project) {
             task.from (compileSass.map (CompileSass::getOutputDir));
           }
         });
+    project.getSubprojects().forEach(
+        subProject -> compileSass(subProject, extension, installSass)
+    );
   }
 
   private String archiveName (String version) {