import groovy.json.JsonSlurper
import org.gradle.initialization.DefaultSettings
import org.apache.tools.ant.taskdefs.condition.Os

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

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

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

{{ packageImports }}

public class PackageList {
  private Application application;
  private ReactNativeHost reactNativeHost;
  private MainPackageConfig mConfig;

  public PackageList(ReactNativeHost reactNativeHost) {
    this(reactNativeHost, null);
  }

  public PackageList(Application application) {
    this(application, null);
  }

  public PackageList(ReactNativeHost reactNativeHost, MainPackageConfig config) {
    this.reactNativeHost = reactNativeHost;
    mConfig = config;
  }

  public PackageList(Application application, MainPackageConfig config) {
    this.reactNativeHost = null;
    this.application = application;
    mConfig = config;
  }

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

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

  private Application getApplication() {
    if (this.reactNativeHost == null) return this.application;
    return this.reactNativeHost.getApplication();
  }

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

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

class ReactNativeModules {
  private Logger logger
  private String packageName
  private File root
  private ArrayList<HashMap<String, String>> reactNativeModules
  private HashMap<String, ArrayList> reactNativeModulesBuildVariants

  private static String LOG_PREFIX = ":ReactNative:"

  ReactNativeModules(Logger logger, File root) {
    this.logger = logger
    this.root = root

    def (nativeModules, reactNativeModulesBuildVariants, packageName) = this.getReactNativeConfig()
    this.reactNativeModules = nativeModules
    this.reactNativeModulesBuildVariants = reactNativeModulesBuildVariants
    this.packageName = packageName
  }

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

  /**
   * Adds the react native modules as dependencies to the users `app` project
   */
  void addReactNativeModuleDependencies(Project appProject) {
    reactNativeModules.forEach { reactNativeModule ->
      def nameCleansed = reactNativeModule["nameCleansed"]
      def dependencyConfiguration = reactNativeModule["dependencyConfiguration"]
      appProject.dependencies {
        if (reactNativeModulesBuildVariants.containsKey(nameCleansed)) {
          reactNativeModulesBuildVariants
            .get(nameCleansed)
            .forEach { buildVariant -> 
              if(dependencyConfiguration != null) {
                "${buildVariant}${dependencyConfiguration}"
              } else {
                "${buildVariant}Implementation" project(path: ":${nameCleansed}")
              }
            }
        } else {
          if(dependencyConfiguration != null) {
            "${dependencyConfiguration}"
          } else {
             implementation project(path: ":${nameCleansed}")
          }
        }
      }
    }
  }

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

    String packageImports = ""
    String packageClassInstances = ""

    if (packages.size() > 0) {
      def interpolateDynamicValues = {
        it
                // Before adding the package replacement mechanism,
                // BuildConfig and R classes were imported automatically
                // into the scope of the file. We want to replace all
                // non-FQDN references to those classes with the package name 
                // of the MainApplication.
                //
                // We want to match "R" or "BuildConfig":
                //  - new Package(R.string…),
                //  - Module.configure(BuildConfig);
                //    ^ hence including (BuildConfig|R)
                // but we don't want to match "R":
                //  - new Package(getResources…),
                //  - new PackageR…,
                //  - new Royal…,
                //    ^ hence excluding \w before and after matches
                // and "BuildConfig" that has FQDN reference:
                //  - Module.configure(com.acme.BuildConfig);
                //    ^ hence excluding . before the match.
                .replaceAll(~/([^.\w])(BuildConfig|R)([^\w])/, {
                  wholeString, prefix, className, suffix ->
                    "${prefix}${packageName}.${className}${suffix}"
                })
      }
      packageImports = packages.collect {
        "// ${it.name}\n${interpolateDynamicValues(it.packageImportPath)}"
      }.join('\n')
      packageClassInstances = ",\n      " + packages.collect {
        interpolateDynamicValues(it.packageInstance)
      }.join(",\n      ")
    }

    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 specified command using Runtime exec() in a specified directory.
   * Throws when the command result is empty.
   */
  String getCommandOutput(String[] command, File directory) {
    try {
      def output = ""
      def cmdProcess = Runtime.getRuntime().exec(command, null, directory)
      def bufferedReader = new BufferedReader(new InputStreamReader(cmdProcess.getInputStream()))
      def buff = ""
      def readBuffer = new StringBuffer()
      while ((buff = bufferedReader.readLine()) != null) {
        readBuffer.append(buff)
      }
      output = readBuffer.toString()
      if (!output) {
        this.logger.error("${LOG_PREFIX}Unexpected empty result of running '${command}' command.")
        def bufferedErrorReader = new BufferedReader(new InputStreamReader(cmdProcess.getErrorStream()))
        def errBuff = ""
        def readErrorBuffer = new StringBuffer()
        while ((errBuff = bufferedErrorReader.readLine()) != null) {
          readErrorBuffer.append(errBuff)
        }
        throw new Exception(readErrorBuffer.toString())
      }
      return output
    } catch (Exception exception) {
      this.logger.error("${LOG_PREFIX}Running '${command}' command failed.")
      throw exception
    }
  }

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

    ArrayList<HashMap<String, String>> reactNativeModules = new ArrayList<HashMap<String, String>>()
    HashMap<String, ArrayList> reactNativeModulesBuildVariants = new HashMap<String, ArrayList>()
    
    /**
     * Resolve the CLI location from Gradle file
     *
     * @todo: Sometimes Gradle can be called outside of the JavaScript hierarchy (-p flag) which
     * will fail to resolve the script and the dependencies. We should resolve this soon.
     *
     * @todo: `fastlane` has been reported to not work too.
     */
    def cliResolveScript = "console.log(require('react-native/cli').bin);"
    String[] nodeCommand = ["node", "-e", cliResolveScript]
    def cliPath = this.getCommandOutput(nodeCommand, this.root)

    String[] reactNativeConfigCommand = ["node", cliPath, "config"]
    def reactNativeConfigOutput = this.getCommandOutput(reactNativeConfigCommand, this.root)

    def json
    try {
      json = new JsonSlurper().parseText(reactNativeConfigOutput)
    } catch (Exception exception) {
      throw new Exception("Calling `${reactNativeConfigCommand}` finished with an exception. Error message: ${exception.toString()}. Output: ${reactNativeConfigOutput}");
    }
    def dependencies = json["dependencies"]
    def project = json["project"]["android"]

    if (project == null) {
      throw new Exception("React Native CLI failed to determine Android project configuration. This is likely due to misconfiguration. Config output:\n${json.toMapString()}")
    }

    def engine = new groovy.text.SimpleTemplateEngine()

    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>()
        def nameCleansed = name.replaceAll('[~*!\'()]+', '_').replaceAll('^@([\\w-.]+)/', '$1_')
        reactNativeModuleConfig.put("name", name)
        reactNativeModuleConfig.put("nameCleansed", nameCleansed)
        reactNativeModuleConfig.put("androidSourceDir", androidConfig["sourceDir"])
        reactNativeModuleConfig.put("packageInstance", androidConfig["packageInstance"])
        reactNativeModuleConfig.put("packageImportPath", androidConfig["packageImportPath"])
        if (androidConfig["buildTypes"] && !androidConfig["buildTypes"].isEmpty()) {
          reactNativeModulesBuildVariants.put(nameCleansed, androidConfig["buildTypes"])
        }
        if(androidConfig.containsKey("dependencyConfiguration")) {
          reactNativeModuleConfig.put("dependencyConfiguration", androidConfig["dependencyConfiguration"])
        } else if (project.containsKey("dependencyConfiguration")) {
          def bindings = ["dependencyName": nameCleansed]
          def template = engine.createTemplate(project["dependencyConfiguration"]).make(bindings)

          reactNativeModuleConfig.put("dependencyConfiguration", template.toString())
        }

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

    return [reactNativeModules, reactNativeModulesBuildVariants, json["project"]["android"]["packageName"]];
  }
}

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

ext.applyNativeModulesSettingsGradle = { DefaultSettings defaultSettings, File root = null ->
  def projectRoot = rootProject.projectDir
  if (root != null) {
    projectRoot = root
  }

  def autoModules = new ReactNativeModules(logger, projectRoot)
  autoModules.addReactNativeModuleProjects(defaultSettings)
}

ext.applyNativeModulesAppBuildGradle = { Project project, File root = null ->
  def projectRoot = rootProject.projectDir
  if (root != null) {
    projectRoot = root
  }

  def autoModules = new ReactNativeModules(logger, projectRoot)
  autoModules.addReactNativeModuleDependencies(project)

  def generatedSrcDir = new File(buildDir, "generated/rncli/src/main/java")
  def generatedCodeDir = new File(generatedSrcDir, generatedFilePackage.replace('.', '/'))

  task generatePackageList {
    doLast {
      autoModules.generatePackagesFile(generatedCodeDir, generatedFileName, generatedFileContentsTemplate)
    }
  }

  preBuild.dependsOn generatePackageList

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