native_modules.gradle

import groovy.json.JsonSlurper
import org.gradle.initialization.DefaultSettings

def generatedFileName = "PackageList.java"
def generatedFileContentsTemplate = """
package com.facebook.react;

import android.app.Application;
import android.content.Context;
import android.content.res.Resources;

import com.facebook.react.ReactPackage;
import com.facebook.react.shell.MainReactPackage;
import java.util.Arrays;
import java.util.List;

{{ packageImports }}

public class PackageList {
  private ReactNativeHost reactNativeHost;
  public PackageList(ReactNativeHost reactNativeHost) {
    this.reactNativeHost = reactNativeHost;
  }

  private ReactNativeHost getReactNativeHost() {
    return this.reactNativeHost;
  }

  private Resources getResources() {
    return this.getApplication().getResources();
  }

  private Application getApplication() {
    return this.reactNativeHost.getApplication();
  }

  private Context getApplicationContext() {
    return this.getApplication().getApplicationContext();
  }

  public List<ReactPackage> getPackages() {
    return Arrays.<ReactPackage>asList(
      new MainReactPackage(){{ packageClassInstances }}
    );
  }
}
"""

class ReactNativeModules {
  private Logger logger
  private Project project
  private DefaultSettings defaultSettings
  private ExtraPropertiesExtension extension
  private ArrayList<HashMap<String, String>> reactNativeModules

  private static String LOG_PREFIX = ":ReactNative:"
  private static String REACT_NATIVE_CLI_BIN = "node_modules${File.separator}@react-native-community${File.separator}cli${File.separator}build${File.separator}index.js"
  private static String REACT_NATIVE_CONFIG_CMD = "node ${REACT_NATIVE_CLI_BIN} config"

  ReactNativeModules(Logger logger) {
    this.logger = logger
  }

  void applySettingsGradle(DefaultSettings defaultSettings, ExtraPropertiesExtension extraPropertiesExtension) {
    this.defaultSettings = defaultSettings
    this.extension = extraPropertiesExtension
    this.reactNativeModules = this.getReactNativeConfig()

    addReactNativeModuleProjects()
  }

  void applyBuildGradle(Project project, ExtraPropertiesExtension extraPropertiesExtension) {
    this.project = project
    this.extension = extraPropertiesExtension
    this.reactNativeModules = this.getReactNativeConfig()

    addReactNativeModuleDependencies()
  }

  /**
   * Include the react native modules android projects and specify their project directory
   */
  void addReactNativeModuleProjects() {
    reactNativeModules.forEach { reactNativeModule ->
      String name = reactNativeModule["name"]
      String androidSourceDir = reactNativeModule["androidSourceDir"]
      defaultSettings.include(":${name}")
      defaultSettings.project(":${name}").projectDir = new File("${androidSourceDir}")
    }
  }

  /**
   * Adds the react native modules as dependencies to the users `app` project
   */
  void addReactNativeModuleDependencies() {
    reactNativeModules.forEach { reactNativeModule ->
      def name = reactNativeModule["name"]
      project.dependencies {
        // TODO(salakar): are other dependency scope methods such as `api` required?
        implementation project(path: ":${name}")
      }
    }
  }

  /**
   * This returns the users project root (e.g. where the node_modules dir is located).
   *
   * This defaults to up one directory from the root android directory unless the user has defined
   * a `ext.reactNativeProjectRoot` extension property
   *
   * @return
   */
  File getReactNativeProjectRoot() {
    if (this.extension.has("reactNativeProjectRoot")) {
      File rnRoot = File(this.extension.get("reactNativeProjectRoot"))
      // allow custom React Native project roots for non-standard directory structures
      this.logger.debug("${LOG_PREFIX}Using custom React Native project root path '${rnRoot.toString()}'")
      return rnRoot
    }

    File androidRoot

    if (this.project) {
      androidRoot = this.project.rootProject.projectDir
    } else {
      androidRoot = this.defaultSettings.rootProject.projectDir
    }

    this.logger.debug("${LOG_PREFIX}Using default React Native project root path '${androidRoot.parentFile.toString()}'")
    return androidRoot.parentFile
  }

  /**
   * Code-gen a java file with all the detected ReactNativePackage instances automatically added
   *
   * @param outputDir
   * @param generatedFileName
   * @param generatedFileContentsTemplate
   * @param applicationId
   */
  void generatePackagesFile(File outputDir, String generatedFileName, String generatedFileContentsTemplate, String applicationId) {
    ArrayList<HashMap<String, String>>[] packages = this.reactNativeModules

    String packageImports = ""
    String packageClassInstances = ""

    if (packages.size() > 0) {
      packageImports = "import ${applicationId}.BuildConfig;\n\n"
      packageImports = packageImports + packages.collect {
        "// ${it.name}\n${it.packageImportPath}"
      }.join(';\n')
      packageClassInstances = ",\n      " + packages.collect { it.packageInstance }.join(',')
    }

    String generatedFileContents = generatedFileContentsTemplate
      .replace("{{ packageImports }}", packageImports)
      .replace("{{ packageClassInstances }}", packageClassInstances)

    outputDir.mkdirs()
    final FileTreeBuilder treeBuilder = new FileTreeBuilder(outputDir)
    treeBuilder.file(generatedFileName).newWriter().withWriter { w ->
      w << generatedFileContents
    }
  }

  /**
   * Runs a process to call the React Native CLI Config command and parses the output
   *
   * @return ArrayList < HashMap < String , String > >
   */
  ArrayList<HashMap<String, String>> getReactNativeConfig() {
    if (this.reactNativeModules != null) return this.reactNativeModules
    ArrayList<HashMap<String, String>> reactNativeModules = new ArrayList<HashMap<String, String>>()

    def cmdProcess

    try {
      cmdProcess = Runtime.getRuntime().exec(REACT_NATIVE_CONFIG_CMD, null, getReactNativeProjectRoot())
      cmdProcess.waitFor()
    } catch (Exception exception) {
      this.logger.warn("${LOG_PREFIX}${exception.message}")
      this.logger.warn("${LOG_PREFIX}Automatic import of native modules failed. (UNKNOWN)")
      return reactNativeModules
    }

    def reactNativeConfigOutput = cmdProcess.in.text
    def json = new JsonSlurper().parseText(reactNativeConfigOutput)
    def dependencies = json["dependencies"]

    dependencies.each { name, value ->
      def platformsConfig = value["platforms"];
      def androidConfig = platformsConfig["android"]

      if (androidConfig != null && androidConfig["sourceDir"] != null) {
        this.logger.info("${LOG_PREFIX}Automatically adding native module '${name}'")

        HashMap reactNativeModuleConfig = new HashMap<String, String>()
        reactNativeModuleConfig.put("name", name)
        reactNativeModuleConfig.put("androidSourceDir", androidConfig["sourceDir"])
        reactNativeModuleConfig.put("packageInstance", androidConfig["packageInstance"])
        reactNativeModuleConfig.put("packageImportPath", androidConfig["packageImportPath"])
        this.logger.trace("${LOG_PREFIX}'${name}': ${reactNativeModuleConfig.toMapString()}")

        reactNativeModules.add(reactNativeModuleConfig)
      } else {
        this.logger.info("${LOG_PREFIX}Skipping native module '${name}'")
      }
    }

    return reactNativeModules
  }
}

/** -----------------------
 *    Exported Extensions
 * ------------------------ */

def autoModules = new ReactNativeModules(logger)

ext.applyNativeModulesSettingsGradle = { DefaultSettings defaultSettings ->
  autoModules.applySettingsGradle(defaultSettings, ext)
}

ext.applyNativeModulesAppBuildGradle = { Project project ->
  autoModules.applyBuildGradle(project, ext)

  def applicationId
  def generatedSrcDir = new File(buildDir, "generated/rncli/src/main/java/com/facebook/react")

  // TODO(salakar): not sure if this is the best way of getting the package name (used to import BuildConfig)
  project.android.applicationVariants.all { variant ->
    applicationId = [variant.mergedFlavor.applicationId, variant.buildType.applicationIdSuffix].findAll().join()
  }

  task generatePackageList << {
    autoModules.generatePackagesFile(generatedSrcDir, generatedFileName, generatedFileContentsTemplate, applicationId)
  }

  preBuild.dependsOn generatePackageList

  android {
    sourceSets {
      main {
        java {
          srcDirs += generatedSrcDir
        }
      }
    }
  }
}