codegen Gradle: introduce com.facebook.react.codegen plugin to replace architecture.gradle script

Summary:
Instead of applying configs from gradle scripts, this introduces a proper Gradle plugin to enable Codegen in an application or library project. In the build.gradle, one enables it by:

```
plugins {
    id("com.android.application")
    id("com.facebook.react.codegen") // <---
}

// ...

react { // <--- the new plugin extension
    enableCodegen = System.getenv("USE_CODEGEN")
    jsRootDir = file("$rootDir/RNTester")
    reactNativeRootDir = file("$rootDir")
}
```

The plugin supports `react` plugin extension as demonstrated above. Adding this:
* automatically generates all TurboModule Java files via react-native-codegen **before the `preBuild` Gradle task**
* automatically adds the files to the `android {}` project configuration
* is done per project (build.gradle)

This will be the foundation for future React Native gradle plugin beyond just for react-native-codegen.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D23065685

fbshipit-source-id: 4ea67e48fab33b238c0973463cdb00de8cdadfcc

RNTester/android/app/build.gradle

@@ -123,7 +123,7 @@ android {
     }
 
     dexOptions {
-       javaMaxHeapSize "4g"
+        javaMaxHeapSize "4g"
     }
 
     flavorDimensions "vm"
@@ -222,3 +222,9 @@ dependencies {
     androidTestImplementation('com.wix:detox:+') { transitive = true }
     androidTestImplementation 'junit:junit:4.12'
 }
+
+react {
+    enableCodegen = System.getenv("USE_CODEGEN") ?: false
+    jsRootDir = file("$rootDir/RNTester")
+    reactNativeRootDir = file("$rootDir")
+}

ReactAndroid/build.gradle

@@ -7,9 +7,9 @@
 
 plugins {
     id("com.android.library")
+    id("com.facebook.react.codegen")
     id("maven")
     id("de.undercouch.download")
-    id("com.facebook.react.codegen")
 }
 
 import java.nio.file.Paths
@@ -465,8 +465,9 @@ dependencies {
 }
 
 apply(from: "release.gradle")
-apply(from: "../architecture.gradle");
-generateNativeArtifactsFromJavaScript([
-    enableCodegen: System.getenv("USE_CODEGEN"),
-    jsRootDir: "${file('../Libraries')}",
-])
+
+react {
+    enableCodegen = System.getenv("USE_CODEGEN") ?: false
+    jsRootDir = file("../Libraries")
+    reactNativeRootDir = file("$rootDir")
+}

architecture.gradle

@@ -1,88 +0,0 @@
-/*
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-
-def codegenDir = "$rootDir/packages/react-native-codegen";
-def codegenGenerateSchemaCli = "$codegenDir/lib/cli/combine/combine-js-to-schema-cli.js";
-def codegenGenerateNativeModuleSpecsCli = "$rootDir/scripts/generate-native-modules-specs-cli.js";
-def schemaFile = "schema.json";
-
-// TODO: Consider building Gradle plugin instead.
-
-/**
- * The config is derived from app-level `project.react`.
- */
-ext.generateNativeArtifactsFromJavaScript = { Map config ->
-  def nodeExecutableAndArgs = config.nodeExecutableAndArgs ?: ["node"];
-  def jsRootDir = config.jsRootDir ?: config.root;
-
-  if (!config.enableCodegen) {
-    return;
-  }
-
-  // 1. Create build dir
-  def generatedSrcDir = file("$buildDir/generated/source/codegen");
-
-  // 2. Produce schema from JS files.
-  task generateCodegenSchemaFromJavaScript(type: Exec) {
-    doFirst {
-      generatedSrcDir.deleteDir()
-      generatedSrcDir.mkdirs()
-    }
-
-    def schemaOutputFile = file("$generatedSrcDir/$schemaFile");
-
-    inputs.files fileTree(dir: codegenDir)
-    inputs.files fileTree(dir: jsRootDir)
-    outputs.file(schemaOutputFile)
-
-    def execCommands = ["yarn"] + nodeExecutableAndArgs + [
-      codegenGenerateSchemaCli,
-      "$schemaOutputFile",
-      jsRootDir,
-    ];
-    commandLine execCommands
-
-    ext.schema = {
-      schemaOutputFile
-    }
-  }
-
-  // 3. Generate Java code from schema
-  task generateCodegenArtifactsFromSchema(dependsOn: 'generateCodegenSchemaFromJavaScript', type: Exec) {
-
-    def generatedSchema = tasks.generateCodegenSchemaFromJavaScript.schema();
-    def javaPackageName = config.codegenJavaPackageName ?: "com.facebook.fbreact.specs.beta";
-    def javaPackageDir = javaPackageName.replace(".", "/");
-    def outputDir = file("$generatedSrcDir/java/$javaPackageDir");
-
-    inputs.files fileTree(dir: codegenDir)
-    inputs.files generatedSchema
-    outputs.dir(outputDir)
-
-    def execCommands = ["yarn"] + nodeExecutableAndArgs + [
-      codegenGenerateNativeModuleSpecsCli,
-      "android",
-      "$generatedSchema",
-      "$outputDir",
-    ];
-    commandLine execCommands
-  }
-
-  // 4. add deps + srcs
-  preBuild.dependsOn generateCodegenArtifactsFromSchema
-
-  android {
-    sourceSets {
-      main {
-        java {
-          srcDirs += "$generatedSrcDir/java"
-        }
-      }
-    }
-  }
-}

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/build.gradle

@@ -19,5 +19,7 @@ gradlePlugin {
 }
 
 dependencies {
+    implementation 'com.android.tools.build:gradle:3.5.3'
+    implementation 'com.google.guava:guava:29.0-jre'
     implementation 'com.squareup:javapoet:1.13.0'
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/plugin/CodegenPlugin.java

@@ -7,31 +7,137 @@
 
 package com.facebook.react.codegen.plugin;
 
-import com.facebook.react.codegen.generator.JavaGenerator;
-import java.io.IOException;
+import com.android.build.gradle.BaseExtension;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableMap;
+import java.io.File;
 import org.gradle.api.Plugin;
 import org.gradle.api.Project;
+import org.gradle.api.Task;
+import org.gradle.api.tasks.Exec;
 
-/** A Gradle plugin to enable code generation from JavaScript in Gradle environment. */
+/**
+ * A Gradle plugin to enable react-native-codegen in Gradle environment. See the Gradle API docs for
+ * more information: https://docs.gradle.org/6.5.1/javadoc/org/gradle/api/Project.html
+ */
 public class CodegenPlugin implements Plugin<Project> {
+
   public void apply(final Project project) {
-    // Register a task
+    final CodegenPluginExtension extension =
+        project.getExtensions().create("react", CodegenPluginExtension.class, project);
+
+    // 1. Set up build dir.
+    final File generatedSrcDir = new File(project.getBuildDir(), "generated/source/codegen");
+    final File generatedSchemaFile = new File(generatedSrcDir, "schema.json");
+
+    // 2. Task: produce schema from JS files.
     project
         .getTasks()
         .register(
-            "generateJava",
+            "generateCodegenSchemaFromJavaScript",
+            Exec.class,
             task -> {
-              task.doLast(
+              if (!extension.enableCodegen) {
+                return;
+              }
+
+              task.doFirst(
                   s -> {
-                    if (System.getenv("USE_CODEGEN").isEmpty()) {
-                      return;
-                    }
-                    try {
-                      JavaGenerator generator = new JavaGenerator("", "");
-                      generator.build();
-                    } catch (IOException e) {
-                    }
+                    generatedSrcDir.delete();
+                    generatedSrcDir.mkdirs();
                   });
+
+              task.getInputs()
+                  .files(project.fileTree(ImmutableMap.of("dir", extension.codegenDir())));
+              task.getInputs()
+                  .files(
+                      project.fileTree(
+                          ImmutableMap.of(
+                              "dir",
+                              extension.jsRootDir,
+                              "includes",
+                              ImmutableList.of("**/*.js"))));
+              task.getOutputs().file(generatedSchemaFile);
+
+              ImmutableList<String> execCommands =
+                  new ImmutableList.Builder<String>()
+                      .add("yarn")
+                      .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
+                      .add(extension.codegenGenerateSchemaCLI().getAbsolutePath())
+                      .add(generatedSchemaFile.getAbsolutePath())
+                      .add(extension.jsRootDir.getAbsolutePath())
+                      .build();
+              task.commandLine(execCommands);
             });
+
+    // 3. Task: generate Java code from schema.
+    project
+        .getTasks()
+        .register(
+            "generateCodegenArtifactsFromSchema",
+            Exec.class,
+            task -> {
+              if (!extension.enableCodegen) {
+                return;
+              }
+
+              task.dependsOn("generateCodegenSchemaFromJavaScript");
+
+              // TODO: The codegen tool should produce this outputDir structure based on
+              // the provided Java package name.
+              File outputDir =
+                  new File(
+                      generatedSrcDir,
+                      "java/" + extension.codegenJavaPackageName.replace(".", "/"));
+
+              task.getInputs()
+                  .files(project.fileTree(ImmutableMap.of("dir", extension.codegenDir())));
+              task.getInputs().files(generatedSchemaFile);
+              task.getOutputs().dir(outputDir);
+
+              ImmutableList<String> execCommands =
+                  new ImmutableList.Builder<String>()
+                      .add("yarn")
+                      .addAll(ImmutableList.copyOf(extension.nodeExecutableAndArgs))
+                      .add(extension.codegenGenerateNativeModuleSpecsCLI().getAbsolutePath())
+                      .add("android")
+                      .add(generatedSchemaFile.getAbsolutePath())
+                      .add(outputDir.getAbsolutePath())
+                      .build();
+              task.commandLine(execCommands);
+            });
+
+    // 4. Add dependencies & generated sources to the project.
+    // Note: This last step needs to happen after the project has been evaluated.
+    project.afterEvaluate(
+        s -> {
+          if (!extension.enableCodegen) {
+            return;
+          }
+
+          // `preBuild` is one of the base tasks automatically registered by Gradle.
+          // This will invoke the codegen before compiling the entire project.
+          Task preBuild = project.getTasks().findByName("preBuild");
+          if (preBuild != null) {
+            preBuild.dependsOn("generateCodegenArtifactsFromSchema");
+          }
+
+          /**
+           * Finally, update the android configuration to include the generated sources. This
+           * equivalent to this DSL:
+           *
+           * <p>android { sourceSets { main { java { srcDirs += "$generatedSrcDir/java" } } } }
+           *
+           * <p>See documentation at
+           * https://google.github.io/android-gradle-dsl/current/com.android.build.gradle.BaseExtension.html.
+           */
+          BaseExtension android = (BaseExtension) project.getExtensions().getByName("android");
+          android
+              .getSourceSets()
+              .getByName("main")
+              .getJava()
+              .srcDir(new File(generatedSrcDir, "java"));
+          // TODO: Add JNI sources.
+        });
   }
 }

packages/react-native-codegen/android/gradlePlugin-build/gradlePlugin/src/main/java/com/facebook/react/codegen/plugin/CodegenPluginExtension.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.codegen.plugin;
+
+import java.io.File;
+import org.gradle.api.Project;
+
+public class CodegenPluginExtension {
+  // TODO: Remove beta.
+  public String codegenJavaPackageName = "com.facebook.fbreact.specs.beta";
+  public boolean enableCodegen;
+  public File jsRootDir;
+  public String[] nodeExecutableAndArgs = {"node"};
+  public File reactNativeRootDir;
+
+  public CodegenPluginExtension(Project project) {
+    this.reactNativeRootDir = new File(project.getRootDir(), "node_modules/react-native");
+  }
+
+  public File codegenDir() {
+    return new File(this.reactNativeRootDir, "packages/react-native-codegen");
+  }
+
+  public File codegenGenerateSchemaCLI() {
+    return new File(this.codegenDir(), "lib/cli/combine/combine-js-to-schema-cli.js");
+  }
+
+  public File codegenGenerateNativeModuleSpecsCLI() {
+    return new File(this.reactNativeRootDir, "scripts/generate-native-modules-specs-cli.js");
+  }
+}

packages/react-native-codegen/android/settings.gradle

@@ -5,6 +5,14 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        mavenLocal()
+        google()
+    }
+}
+
 rootProject.name = 'react-native-codegen'
 
 include(":generator")

react.gradle

@@ -349,6 +349,3 @@ afterEvaluate {
         }
     }
 }
-
-apply(from: "$rootDir/architecture.gradle");
-generateNativeArtifactsFromJavaScript(project.react);

settings.gradle.kts

@@ -5,6 +5,14 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+pluginManagement {
+    repositories {
+        gradlePluginPortal()
+        mavenLocal()
+        google()
+    }
+}
+
 include(
     ":ReactAndroid",
     ":RNTester:android:app"