import android.view.*;

import android.widget.*;

import android.content.Context;

import android.os.AsyncTask;

import android.support.v4.app.Fragment;

import android.support.v4.app.FragmentActivity;

import android.support.v4.app.FragmentManager;

import java.io.*;

import java.lang.reflect.Method;

import java.net.*;

import dalvik.system.DexClassLoader;

public class main {

  public static View main(final FragmentActivity context) {

    ScrollView sv = new ScrollView(context);

    LinearLayout ll = new LinearLayout(context);

    ll.setOrientation(LinearLayout.VERTICAL);

    LinearLayout line1 = new LinearLayout(context);

    TextView label = new TextView(context);

    label.setText("Run which snippet ID?");

    line1.addView(label);

    final EditText tv = new EditText(context);

    tv.setText("675");

    line1.addView(tv);

    Button btnGo = new Button(context);

    btnGo.setText("Go");

    line1.addView(btnGo);

    ll.addView(line1);

    btnGo.setOnClickListener(new View.OnClickListener() {

      public void onClick(View v) {

        String snippetID = tv.getText().toString();

        String text = "Running: " + snippetID;

        Toast.makeText(context, text, 2000).show();

        new DynamicRunner(context).run(snippetID);

      }

    });

    sv.addView(ll);

    return sv;

  }

}

class DynamicRunner {

  private static final String mainClassName = "main" /*"test"*/;

  private static final String mainMethodName = "main" /*"run"*/;

  private final FragmentActivity activity;

  StringBuffer info = new StringBuffer();

  public DynamicRunner(FragmentActivity activity) {

    this.activity = activity;

  }

  public void run(String snippetID) {

    try {

      URL url = new URL(

                    /*"http://tinybrain.de/downloads/test.dex"*/

        "http://tinybrain.de:8080/dexcompile.php?id=" + snippetID);

      new DownloadFilesTask().execute(url);

    } catch (Throwable e) {

      showError(e);

    }

  }

  static byte[] DEX_FILE_MAGIC = { 0x64, 0x65, 0x78, 0x0a, 0x30, 0x33, 0x35, 0x00 };

  private Class<?> runDynamic(URL url) throws IOException, ClassNotFoundException {

    info.append("Loading dex: " + url.toString() + "\n");

    byte[] dexData = loadBinaryPage(url.openConnection());

    if (!isDex(dexData))

      throw new RuntimeException("Dex generation error: " + dexData.length + " bytes - " + new String(dexData, "UTF-8"));

    info.append("Dex data length: " + dexData.length + "\n");

    File dexDir = activity.getDir("dex", Context.MODE_PRIVATE);

    File dexFile;

    do {

      dexFile = new File(dexDir, System.currentTimeMillis() + ".dex");

    } while (dexFile.exists());

    File dexOutputDir;

    do {

      dexOutputDir = activity.getDir("dex-optimized-" + System.currentTimeMillis(), Context.MODE_PRIVATE);

    } while (dexOutputDir.list().length != 0);

    FileOutputStream fileOutputStream = new FileOutputStream(dexFile);

    fileOutputStream.write(dexData);

    fileOutputStream.close();

    ClassLoader parentClassLoader =

      //ClassLoader.getSystemClassLoader(); // does not find support jar

      //getClass().getClassLoader(); // Let's try this...

      getClass().getClassLoader().getParent(); // XXX !

    DexClassLoader classLoader = new DexClassLoader(dexFile.getAbsolutePath(), dexOutputDir.getAbsolutePath(), null,

      parentClassLoader);

    Class<?> theClass = classLoader.loadClass(mainClassName);

    return theClass;

  }

  private boolean isDex(byte[] dexData) {

    if (dexData.length < DEX_FILE_MAGIC.length) return false;

    for (int i = 0; i < DEX_FILE_MAGIC.length; i++)

      if (dexData[i] != DEX_FILE_MAGIC[i])

        return false;

    return true;

  }

  private void showError(Throwable e) {

    ScrollView scrollView = new ScrollView(activity);

    TextView errorView = new TextView(activity);

    errorView.setText(info + "\n" + getStackTrace(e));

    scrollView.addView(errorView);

    activity.setContentView(scrollView);

  }

  public static String getStackTrace(Throwable throwable) {

    StringWriter writer = new StringWriter();

    throwable.printStackTrace(new PrintWriter(writer));

    return writer.toString();

  }

  private class DownloadFilesTask extends AsyncTask<URL, Integer, Class<?>> {

    volatile Throwable error;

    URL url;

    protected Class<?> doInBackground(URL... urls) {

      try {

        url = urls[0];

        return runDynamic(url);

      } catch (Throwable e) {

        error = e;

        return null;

      }

    }

    protected void onProgressUpdate(Integer... progress) {

      //setProgressPercent(progress[0]);

    }

    protected void onPostExecute(Class<?> theClass) {

      try {

        if (error != null)

          showError(error);

        else if (theClass != null) {

          Method run = findMainMethod(theClass);

          Object result = run.invoke(null, activity);

          if (result instanceof Fragment) {

            FragmentManager fm = activity.getSupportFragmentManager();

            android.support.v4.app.Fragment fragment = fm.findFragmentByTag("mainFragment");

            if (fragment == null) {

              android.support.v4.app.FragmentTransaction ft = fm.beginTransaction();

              fragment = (Fragment) result;

              ft.add(android.R.id.content, fragment, "mainFragment");

              ft.commit();

            }

          } else if (result instanceof View) {

            activity.setContentView((View) result);

          } else

            showError(new Throwable("Bad return value from " + url + ", expected View or Fragment: " + result));

        } else

          showError(new Throwable("What?"));

      } catch (Throwable e) {

        showError(e);

      }

    }

  }

  static Method findMainMethod(Class<?> theClass) {

    for (Method method : theClass.getMethods())

      if (method.getName().equals(mainMethodName) && method.getParameterTypes().length == 1)

        return method;

    throw new RuntimeException("Method " + mainMethodName + " with 1 paramter not found in " + theClass.getName());

  }

  public static byte[] loadBinaryPage(URLConnection con) throws IOException {

    //setHeaders(con);

    ByteArrayOutputStream buf = new ByteArrayOutputStream();

    InputStream inputStream = con.getInputStream();

    while (true) {

      int ch = inputStream.read();

      if (ch < 0)

        break;

      buf.write(ch);

    }

    inputStream.close();

    return buf.toByteArray();

  }

}