import java.io.*;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLClassLoader;

import java.util.ArrayList;

import java.util.List;

/**

 * javax by Stefan Reich (www.superinformatiker.de, info@superinformatiker.de)

 *

 * jaxax compiles and runs a bunch of Java sources in one step.

 *

 * Syntax:

 *   javax         (searches for sources in current dir)

 *   javax srcdir  (searches in given directory)

 *

 * Main class must be called "main" in default package.

 *

 * Requirements:

 *   Java 6 or higher - JDK (javac) must be in path

 *

 * Limitations:

 *   Linux only, right now (invokes bash to call javac)

 *   Can't pass arguments to invoked program yet (would be easy to add)

 *

 * TODO: delete .class files at program end

 */

 public class javax {

  public static void main(String[] args) throws IOException, ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {

    File srcDir = new File(args.length == 0 ? "." : args[0]);

    List<File> sources = new ArrayList<File>();

    System.out.println("Scanning for sources in " + srcDir.getPath());

    scanForSources(srcDir, sources);

    if (sources.isEmpty()) {

      System.out.println("No sources found");

      return;

    }

    File optionsFile = File.createTempFile("javax", "");

    File classesDir = new File(System.getProperty("user.home"), ".javax/" + System.currentTimeMillis());

    System.out.println("Compiling " + sources.size() + " source(s) to " + classesDir.getPath());

    String options = "-d " + bashQuote(classesDir.getPath());

    writeOptions(sources, optionsFile, options);

    classesDir.mkdirs();

    invokeJavac(optionsFile);

    System.out.println("Running program (class main.java)\n");

    runProgram(classesDir);

  }

  private static void runProgram(File classesDir) throws MalformedURLException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException, IllegalAccessException {

    URLClassLoader classLoader = new URLClassLoader(new URL[]{classesDir.toURI().toURL()});

    Class<?> mainClass = classLoader.loadClass("main");

    Method main = mainClass.getMethod("main", String[].class);

    main.invoke(null, (Object) new String[0]);

  }

  private static void invokeJavac(File optionsFile) throws IOException {

    String javacOutput = backtick("javac " + bashQuote("@" + optionsFile.getPath()));

    System.out.println(javacOutput);

  }

  private static void writeOptions(List<File> sources, File sourcesFile, String moreOptions) throws IOException {

    FileWriter writer = new FileWriter(sourcesFile);

    for (File source : sources)

      writer.write(bashQuote(source.getPath()) + " ");

    writer.write(moreOptions);

    writer.close();

  }

  private static void scanForSources(File source, List<File> sources) {

    if (source.isFile() && source.getName().endsWith(".java"))

      sources.add(source);

    else if (source.isDirectory()) {

      File[] files = source.listFiles();

      for (File file : files)

        scanForSources(file, sources);

    }

  }

  public static String backtick(String cmd) throws IOException {

    File outFile = File.createTempFile("_backtick", "");

    File scriptFile = File.createTempFile("_backtick", "");

    String command = cmd + ">" + bashQuote(outFile.getPath()) + " 2>&1";

    //Log.info("[Backtick] " + command);

    try {

      saveTextFile(scriptFile.getPath(), command);

      String[] command2 = {"/bin/bash", scriptFile.getPath() };

      Process process = Runtime.getRuntime().exec(command2);

      try {

        process.waitFor();

      } catch (InterruptedException e) {

        throw new RuntimeException(e);

      }

      int value = process.exitValue();

      //Log.info("exit value: " + value);

      return loadTextFile(outFile.getPath(), "");

    } finally {

      scriptFile.delete();

    }

  }

  /** possoibly improvable */

  public static String bashQuote(String text) {

    if (text == null) return null;

    return "\"" + text

      .replace("\\", "\\\\")

      .replace("\"", "\\\"")

      .replace("\n", "\\n")

      .replace("\r", "\\r") + "\"";

  }

  public final static String charsetForTextFiles = "UTF8";

  /** writes safely (to temp file, then rename) */

  public static void saveTextFile(String fileName, String contents) throws IOException {

    File file = new File(fileName);

    File parentFile = file.getParentFile();

    if (parentFile != null)

      parentFile.mkdirs();

    String tempFileName = fileName + "_temp";

    FileOutputStream fileOutputStream = new FileOutputStream(tempFileName);

    OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream, charsetForTextFiles);

    PrintWriter printWriter = new PrintWriter(outputStreamWriter);

    printWriter.print(contents);

    printWriter.close();

    if (file.exists() && !file.delete())

      throw new IOException("Can't delete " + fileName);

    if (!new File(tempFileName).renameTo(file))

      throw new IOException("Can't rename " + tempFileName + " to " + fileName);

  }

  public static String loadTextFile(String fileName, String defaultContents) throws IOException {

    if (!new File(fileName).exists())

      return defaultContents;

    FileInputStream fileInputStream = new FileInputStream(fileName);

    InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, charsetForTextFiles);

    return loadTextFile(inputStreamReader);

  }

  public static String loadTextFile(Reader reader) throws IOException {

    StringBuilder builder = new StringBuilder();

    try {

      BufferedReader bufferedReader = new BufferedReader(reader);

      String line;

      while ((line = bufferedReader.readLine()) != null)

        builder.append(line).append('\n');

    } finally {

      reader.close();

    }

    return builder.length() == 0 ? "" : builder.substring(0, builder.length()-1);

  }

}