import java.io.*;

import java.net.URL;

import java.net.URLConnection;

import java.security.MessageDigest;

import java.security.NoSuchAlgorithmException;

import java.util.ArrayList;

import java.util.List;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

/**

  Baked single-source-file version of javax3 (multiple class files are unavoidable...)

  javax3 accepts a snippet ID as well as a directory name as argument.

 */

public class javax3 {

  static boolean verbose = false;

  private static String isCompilable = "http://tinybrain.de/"

    + /*"564"*/"1000251"; // silenced version (but I think we're silencing now anyway)

  private static String isCompilableHash = "8fe3851d7a686b60546a2429a2bde0d9";

  private static String mainAdder = "http://tinybrain.de/1000252";

  private static String mainAdderHash = "ce1e89785facd87ea64a6d9ad16a7aec";

  public static void main(String[] args) throws IOException {

    File ioBaseDir = new File(".");

    String src = ".";

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

      String arg = args[i];

      if (arg.equals("-v"))

        verbose = true;

      else

        src = arg;

    }

    javax3(src, ioBaseDir);

  }

  public static void javax3(String src, File ioDir) throws IOException {

    File srcDir;

    if (isSnippetID(src))

      srcDir = loadSnippetAsMainJava(src);

    else

      srcDir = new File(src);

    Input X = programToInput(srcDir);

    boolean compilable = isCompilable(X);

    if (verbose) System.out.println("Compilable: " + compilable);

    if (!compilable) {

      X = expandProgram(X);

      File file = new File(X.dir, "main.java");

      String program = loadTextFile(file.getPath(), null);

      if (verbose) System.out.println("New program:\n" + program);

      if (program == null)

        throw new RuntimeException("Expansion failed (tried: " + file.getPath() + ")");

    }

    javax2(X.dir, ioDir, false);

  }

  public static File loadSnippetAsMainJava(String snippetID) throws IOException {

    File srcDir = TempDirMaker.make();

    saveTextFile(new File(srcDir, "main.java").getPath(), loadSnippet(snippetID));

    return srcDir;

  }

  public static File loadSnippetAsMainJavaVerified(String snippetID, String hash) throws IOException {

    File srcDir = TempDirMaker.make();

    saveTextFile(new File(srcDir, "main.java").getPath(), loadSnippetVerified(snippetID, hash));

    return srcDir;

  }

  private static Input expandProgram(Input x) throws IOException {

    return runJavaX2_on_snippet(mainAdder, mainAdderHash, x, true);

  }

  private static boolean isCompilable(Input x) throws IOException {

    Input output = runJavaX2_on_snippet(isCompilable, isCompilableHash, x, true);

    return output.hasFile("is-compilable");

  }

  private static Input runJavaX2_on_snippet(String snippetID, String hash, Input x, boolean silent) throws IOException {

    File srcDir = loadSnippetAsMainJavaVerified(snippetID, hash);

    return runJavaX(new Input(srcDir), x, silent);

  }

  private static Input runJavaX(Input originalSrcDir, Input originalInput, boolean silent) throws IOException {

    File ioBaseDir = TempDirMaker.make();

    File srcDir = new File(ioBaseDir, "src");

    File inputDir = new File(ioBaseDir, "input");

    Input input = new Input(inputDir);

    File outputDir = new File(ioBaseDir, "output");

    Input output = new Input(outputDir);

    copyInput(originalSrcDir, new Input(srcDir));

    copyInput(originalInput, input);

    javax2(srcDir, ioBaseDir, silent);

    return output;

  }

  private static void copyInput(Input src, Input dst) throws IOException {

    copyDirectory(src.dir, dst.dir);

  }

  private static Input programToInput(File srcDir) {

    return new Input(srcDir);

  }

  static class Input {

    File dir;

    public Input(File dir) {

      this.dir = dir;

    }

    public boolean hasFile(String name) {

      return new File(dir, name).exists();

    }

  }

  public static void copyDirectory(File src, File dst) throws IOException {

    if (verbose) System.out.println("Copying " + src.getAbsolutePath() + " to " + dst.getAbsolutePath());

    dst.mkdirs();

    File[] files = src.listFiles();

    if (files == null) return;

    for (File file : files) {

      File dst1 = new File(dst, file.getName());

      if (file.isDirectory())

        copyDirectory(file, dst1);

      else {

        if (verbose) System.out.println("Copying " + file.getAbsolutePath() + " to " + dst1.getAbsolutePath());

        copy(file, dst1);

      }

    }

  }

  /** Quickly copy a file without a progress bar or any other fancy GUI... :) */

  public static void copy(File src, File dest) throws IOException {

    FileInputStream inputStream = new FileInputStream(src);

    FileOutputStream outputStream = new FileOutputStream(dest);

    try {

      copy(inputStream, outputStream);

      inputStream.close();

    } finally {

      outputStream.close();

    }

  }

  public static void copy(InputStream in, OutputStream out) throws IOException {

    byte[] buf = new byte[65536];

    while (true) {

      int n = in.read(buf);

      if (n <= 0) return;

      out.write(buf, 0, n);

    }

  }

  /** 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);

  }

  static class DiskSnippetCache {

    final File dir;

    public DiskSnippetCache(File dir) {

      this.dir = dir;

      dir.mkdirs();

    }

    public synchronized String get(long snippetID) throws IOException {

      return loadTextFile(getFile(snippetID).getPath(), null);

    }

    private File getFile(long snippetID) {

      return new File(dir, "" + snippetID);

    }

    public synchronized void put(long snippetID, String snippet) throws IOException {

      saveTextFile(getFile(snippetID).getPath(), snippet);

    }

    public File getDir() {

      return dir;

    }

  }

  public static DiskSnippetCache getSnippetCache() {

    return new DiskSnippetCache(new File(System.getProperty("user.home"), ".tinybrain/snippet-cache"));

  }

  public static String loadSnippetVerified(String snippetID, String hash) throws IOException {

    String text = loadSnippet(snippetID);

    String realHash = getHash(text.getBytes("UTF-8"));

    if (!realHash.equals(hash)) {

      String msg;

      if (hash.isEmpty())

        msg = "Here's your hash for " + snippetID + ", please put in your program: " + realHash;

      else

        msg = "Hash mismatch for " + snippetID + ": " + realHash + " (new) vs " + hash + " - has tinybrain.de been hacked??";

      throw new RuntimeException(msg);

    }

    return text;

  }

  public static String getHash(byte[] data) {

    return bytesToHex(getFullFingerprint(data));

  }

  public static byte[] getFullFingerprint(byte[] data) {

    try {

      return MessageDigest.getInstance("MD5").digest(data);

    } catch (NoSuchAlgorithmException e) {

      throw new RuntimeException(e);

    }

  }

  public static String bytesToHex(byte[] bytes) {

    return bytesToHex(bytes, 0, bytes.length);

  }

  public static String bytesToHex(byte[] bytes, int ofs, int len) {

    StringBuilder stringBuilder = new StringBuilder(len*2);

    for (int i = 0; i < len; i++) {

      String s = "0" + Integer.toHexString(bytes[ofs+i]);

      stringBuilder.append(s.substring(s.length()-2, s.length()));

    }

    return stringBuilder.toString();

  }

  public static String loadSnippet(String snippetID) throws IOException {

    return loadSnippet(parseSnippetID(snippetID));

  }

  public static long parseSnippetID(String snippetID) {

    return Long.parseLong(shortenSnippetID(snippetID));

  }

  private static String shortenSnippetID(String snippetID) {

    if (snippetID.startsWith("#"))

      snippetID = snippetID.substring(1);

    String httpBlaBla = "http://tinybrain.de/";

    if (snippetID.startsWith(httpBlaBla))

      snippetID = snippetID.substring(httpBlaBla.length());

    return snippetID;

  }

  public static boolean isSnippetID(String snippetID) {

    snippetID = shortenSnippetID(snippetID);

    return isInteger(snippetID) && Long.parseLong(snippetID) != 0;

  }

  public static boolean isInteger(String s) {

    return Pattern.matches("\\-?\\d+", s);

  }

  static boolean preferCached = true;

  public static String loadSnippet(long snippetID) throws IOException {

    if (preferCached) {

      String text = getSnippetCache().get(snippetID);

      if (text != null)

        return text;

    }

    String text;

    try {

      URL url = new URL("http://tinybrain.de:8080/getraw.php?id=" + snippetID);

      text = loadPage(url);

    } catch (FileNotFoundException e) {

      throw new IOException("Snippet #" + snippetID + " not found or not public");

    }

    try {

      getSnippetCache().put(snippetID, text);

    } catch (IOException e) {

      System.err.println("Minor warning: Couldn't save snippet to cache ("  + getSnippetCache().getDir() + ")");

    }

    return text;

  }

  private static String loadPage(URL url) throws IOException {

    System.out.println("Loading: " + url.toExternalForm());

    URLConnection con = url.openConnection();

    return loadPage(con, url);

  }

  public static String loadPage(URLConnection con, URL url) throws IOException {

    String contentType = con.getContentType();

    if (contentType == null)

      throw new IOException("Page could not be read: " + url);

    //Log.info("Content-Type: " + contentType);

    String charset = guessCharset(contentType);

    Reader r = new InputStreamReader(con.getInputStream(), charset);

    StringBuilder buf = new StringBuilder();

    while (true) {

      int ch = r.read();

      if (ch < 0)

        break;

      //Log.info("Chars read: " + buf.length());

      buf.append((char) ch);

    }

    return buf.toString();

  }

  public static String guessCharset(String contentType) {

    Pattern p = Pattern.compile("text/html;\\s+charset=([^\\s]+)\\s*");

    Matcher m = p.matcher(contentType);

    /* If Content-Type doesn't match this pre-conception, choose default and hope for the best. */

    return m.matches() ? m.group(1) : "ISO-8859-1";

  }

  public static void javax2(File srcDir, File ioBaseDir, boolean silent) throws IOException {

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

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

    scanForSources(srcDir, sources, true);

    if (sources.isEmpty()) {

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

      return;

    }

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

    File classesDir = TempDirMaker.make();

    if (verbose) 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);

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

    runProgram(classesDir, ioBaseDir, silent);

  }

  private static void runProgram(File classesDir, File ioBaseDir, boolean silent) throws IOException {

    boolean echoOK = false;

    String bashCmd = "(cd " + bashQuote(ioBaseDir.getAbsolutePath()) + " && (java -cp "

      + bashQuote(classesDir.getAbsolutePath()) + " main" + (echoOK ? "; echo ok" : "") + "))";

    if (verbose) System.out.println(bashCmd);

    String output = backtick(bashCmd);

    if (!silent)

      System.out.println(output);

  }

  private static void invokeJavac(File optionsFile) throws IOException {

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

    if (verbose) 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, boolean topLevel) {

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

      sources.add(source);

    else if (source.isDirectory() && !isSkippedDirectoryName(source.getName(), topLevel)) {

      File[] files = source.listFiles();

      for (File file : files)

        scanForSources(file, sources, false);

    }

  }

  private static boolean isSkippedDirectoryName(String name, boolean topLevel) {

    if (topLevel) return false; // input or output ok as highest directory (intentionally specified by user, not just found by a directory scan in which case we probably don't want it. it's more like heuristics actually.)

    return name.equalsIgnoreCase("input") || name.equalsIgnoreCase("output");

  }

  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();

    }

  }

  /** possibly 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";

  public static class TempDirMaker {

    static long lastValue;

    public static File make() {

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

      dir.mkdirs();

      return dir;

    }

    private static long newValue() {

      long value;

      do

        value = System.currentTimeMillis();

      while (value == lastValue);

      lastValue = value;

      return value;

    }

  }

}