/**
 * Serializes a <code>DBObject</code> into a string that can be sent to the database.
 *
 * <p>There is a pool of available encoders. Create a new one as follows:
 *
 * <blockquote>
 *
 * </pre>
 *
 * ByteEncoder encoder = ByteEncoder.get(); // try forever until an encoder is available </pre>
 *
 * </blockquote>
 *
 * <p>Each key/value pair in the <code>DBObject</code> is encoded in the following format:
 *
 * <blockquote>
 *
 * <i>&lt;type (</i><code>byte</code><i>)&gt;&lt;name (</i><code>String</code></i>)&gt;&lt;0 (</i>
 * <code>byte</code><i>)&gt;&lt;data (serialized data)&gt;</i>
 *
 * </blockquote>
 *
 * For example:
 *
 * <blockquote>
 *
 * &lt;<code>NUMBER</code>&gt;&lt;name&gt;0&lt;double&gt; <code>// NUMBER = 1</code><br>
 * &lt;<code>STRING</code>&gt;&lt;name&gt;0&lt;len&gt;&lt;string&gt;0 <code>// STRING = 2</code>
 *
 * </blockquote>
 */
public class ByteEncoder extends Bytes {

  static final boolean DEBUG = Boolean.getBoolean("DEBUG.BE");

  // things that won't get sent in the scope
  static final Set<String> BAD_GLOBALS = new HashSet<String>();

  static {
    BAD_GLOBALS.add("db");
    BAD_GLOBALS.add("local");
    BAD_GLOBALS.add("core");
    BAD_GLOBALS.add("args"); // TODO: should we get rid of this
    BAD_GLOBALS.add("obj"); // TODO: get rid of this
  }

  /**
   * Whether a given field is generated by the db for use by the db
   *
   * @param o an object to check
   * @return whether the object is a db field
   */
  public static boolean dbOnlyField(Object o) {
    if (o == null) return false;

    if (o instanceof String) return dbOnlyField(o.toString());

    return false;
  }

  /**
   * Whether a given field is generated by the db for use by the db
   *
   * @param s a string to check
   * @return whether the string is a db field
   */
  public static boolean dbOnlyField(String s) {
    return s.equals("_ns") || s.equals("_save") || s.equals("_update");
  }

  /**
   * Fetches a new <code>ByteEncoder</code> from the pool of available <code>ByteEncoder</code>s.
   *
   * @return a new <code>ByteEncoder</code>
   */
  public static ByteEncoder get() {
    return _pool.get();
  }

  /**
   * Get the current position of this ByteEncoder
   *
   * @return
   */
  public long getPosition() {
    return _buf.position();
  }

  /**
   * Get the remaining capacity of this ByteEncoder
   *
   * @return
   */
  public long getRemaining() {
    return _buf.remaining();
  }

  /** Resets and returns this encoder to the pool. */
  protected void done() {
    reset();
    _pool.done(this);
  }

  static final SimplePool<ByteEncoder> _pool =
      new SimplePool<ByteEncoder>("ByteEncoders", NUM_ENCODERS, NUM_ENCODERS * 2) {
        protected ByteEncoder createNew() {
          if (D) System.out.println("creating new ByteEncoder");
          return new ByteEncoder();
        }

        protected long memSize(ByteEncoder d) {
          return d._buf.capacity() + (2 * MAX_STRING) + 1024;
        }
      };

  // ----

  private ByteEncoder() {
    _buf = ByteBuffer.allocateDirect(MAX_OBJECT_SIZE + 2048);
    _buf.order(Bytes.ORDER);
  }

  /**
   * Returns the bytes in the bytebuffer. Attempts to leave the bytebuffer in the same state. Note
   * that mark, if set, is lost.
   *
   * @return array of bytes
   */
  public byte[] getBytes() {

    int pos = _buf.position();
    int limit = _buf.limit();

    flip();

    byte[] arr = new byte[_buf.limit()];

    _buf.get(arr);

    flip();

    _buf.position(pos);
    _buf.limit(limit);

    return arr;
  }

  /** Returns encoder to its starting state, ready to encode an object. */
  protected void reset() {
    _buf.position(0);
    _buf.limit(_buf.capacity());
    _flipped = false;
    _dontRef.clear();
  }

  /** Switches the encoder from being write-only to being read-only. */
  protected void flip() {
    _buf.flip();
    _flipped = true;
  }

  /**
   * Encodes a <code>DBObject</code>. This is for the higher level api calls
   *
   * <p>If encoding an object fails, the buffer will be reset to the position prior to this put call
   * and a BufferOverflowException will be thrown
   *
   * @param o the object to encode
   * @return the number of characters in the encoding
   */
  public int putObject(DBObject o) {

    _buf.mark();

    try {
      return putObject(null, o);
    } catch (BufferOverflowException bof) {
      // reset to marked offset and wipe any written data
      _buf.reset();
      _buf.put(new byte[_buf.remaining()]);
      _buf.reset();

      throw new BufferOverflowException();
    }
  }

  /** this is really for embedded objects */
  private int putObject(String name, DBObject o) {
    if (o == null) throw new NullPointerException("can't save a null object");

    if (DEBUG)
      System.out.println(
          "putObject : " + name + " [" + o.getClass() + "]" + " # keys " + o.keySet().size());

    if (_flipped) throw new IllegalStateException("already flipped");
    final int start = _buf.position();

    byte myType = OBJECT;
    if (o instanceof List) myType = ARRAY;

    if (_handleSpecialObjects(name, o)) return _buf.position() - start;

    if (name != null) {
      _put(myType, name);
    }

    final int sizePos = _buf.position();
    _buf.putInt(0); // leaving space for this.  set it at the end

    List transientFields = null;

    if (myType == OBJECT) {
      if (o.containsField("_id")) _putObjectField("_id", o.get("_id"));

      {
        Object temp = o.get("_transientFields");
        if (temp instanceof List) transientFields = (List) temp;
      }
    }

    for (String s : o.keySet()) {

      if (s.equals("_id")) continue;

      if (transientFields != null && transientFields.contains(s)) continue;

      Object val = o.get(s);

      _putObjectField(s, val);
    }
    _buf.put(EOO);

    _buf.putInt(sizePos, _buf.position() - sizePos);
    return _buf.position() - start;
  }

  private void _putObjectField(String name, Object val) {

    if (dbOnlyField(name) || name.equals("_transientFields")) return;

    if (DEBUG) System.out.println("\t put thing : " + name);

    if (name.equals("$where") && val instanceof String) {
      _put(CODE, name);
      _putValueString(val.toString());
      return;
    }

    val = Bytes.applyEncodingHooks(val);

    if (val == null) putNull(name);
    else if (val instanceof Date) putDate(name, (Date) val);
    else if (val instanceof Number) putNumber(name, (Number) val);
    else if (val instanceof String) putString(name, val.toString());
    else if (val instanceof ObjectId) putObjectId(name, (ObjectId) val);
    else if (val instanceof DBObject) putObject(name, (DBObject) val);
    else if (val instanceof Boolean) putBoolean(name, (Boolean) val);
    else if (val instanceof Pattern) putPattern(name, (Pattern) val);
    else if (val instanceof DBRegex) {
      putDBRegex(name, (DBRegex) val);
    } else if (val instanceof Map) putMap(name, (Map) val);
    else if (val instanceof List) putList(name, (List) val);
    else if (val instanceof byte[]) putBinary(name, (byte[]) val);
    else if (val instanceof DBBinary) putBinary(name, (DBBinary) val);
    else if (val.getClass().isArray()) putList(name, Arrays.asList((Object[]) val));
    else if (val instanceof DBPointer) {

      // temporary - there's the notion of "special object" , but for simple level 0...
      DBPointer r = (DBPointer) val;
      putDBPointer(name, r._ns, (ObjectId) r._id);
    } else if (val instanceof DBRefBase) {
      putDBRef(name, (DBRefBase) val);
    } else if (val instanceof DBSymbol) {
      putSymbol(name, (DBSymbol) val);
    } else if (val instanceof DBUndefined) {
      putUndefined(name);
    } else if (val instanceof DBTimestamp) {
      putTimestamp(name, (DBTimestamp) val);
    } else throw new IllegalArgumentException("can't serialize " + val.getClass());
  }

  private void putList(String name, List l) {
    _put(ARRAY, name);
    final int sizePos = _buf.position();
    _buf.putInt(0);

    for (int i = 0; i < l.size(); i++) _putObjectField(String.valueOf(i), l.get(i));

    _buf.put(EOO);
    _buf.putInt(sizePos, _buf.position() - sizePos);
  }

  private void putMap(String name, Map m) {
    _put(OBJECT, name);
    final int sizePos = _buf.position();
    _buf.putInt(0);

    for (Object key : m.keySet()) _putObjectField(key.toString(), m.get(key));

    _buf.put(EOO);
    _buf.putInt(sizePos, _buf.position() - sizePos);
  }

  private boolean _handleSpecialObjects(String name, DBObject o) {

    if (o == null) return false;

    if (o instanceof DBCollection) {
      DBCollection c = (DBCollection) o;
      putDBPointer(name, c.getName(), Bytes.COLLECTION_REF_ID);
      return true;
    }

    if (!_dontRefContains(o) && name != null && o instanceof DBPointer) {
      DBPointer r = (DBPointer) o;
      putDBPointer(name, r._ns, (ObjectId) r._id);
      return true;
    }

    if (!(o instanceof List) && o.get(Bytes.NO_REF_HACK) != null) {
      o.removeField(Bytes.NO_REF_HACK);
      return false;
    }

    if (!_dontRefContains(o) && name != null && !(o instanceof List) && cameFromDB(o)) {
      putDBPointer(name, o.get("_ns").toString(), (ObjectId) (o.get("_id")));
      return true;
    }

    return false;
  }

  protected int putNull(String name) {
    int start = _buf.position();
    _put(NULL, name);
    return _buf.position() - start;
  }

  protected int putUndefined(String name) {
    int start = _buf.position();
    _put(UNDEFINED, name);
    return _buf.position() - start;
  }

  protected int putTimestamp(String name, DBTimestamp ts) {
    int start = _buf.position();
    _put(TIMESTAMP, name);
    _buf.putInt(ts.getTime());
    _buf.putInt(ts.getInc());
    return _buf.position() - start;
  }

  protected int putBoolean(String name, Boolean b) {
    int start = _buf.position();
    _put(BOOLEAN, name);
    _buf.put(b ? (byte) 0x1 : (byte) 0x0);
    return _buf.position() - start;
  }

  protected int putDate(String name, Date d) {
    int start = _buf.position();
    _put(DATE, name);
    _buf.putLong(d.getTime());
    return _buf.position() - start;
  }

  protected int putNumber(String name, Number n) {
    int start = _buf.position();
    if (n instanceof Integer) {
      _put(NUMBER_INT, name);
      _buf.putInt(n.intValue());
    } else if (n instanceof Long) {
      _put(NUMBER_LONG, name);
      _buf.putLong(n.longValue());
    } else {
      _put(NUMBER, name);
      _buf.putDouble(n.doubleValue());
    }
    return _buf.position() - start;
  }

  protected void putBinary(String name, byte[] data) {

    _put(BINARY, name);
    _buf.putInt(4 + data.length);

    _buf.put(B_BINARY);
    _buf.putInt(data.length);
    int before = _buf.position();
    _buf.put(data);
    int after = _buf.position();

    com.mongodb.util.MyAsserts.assertEquals(after - before, data.length);
  }

  protected void putBinary(String name, DBBinary val) {
    _put(BINARY, name);
    _buf.putInt(val._data.length);
    _buf.put(val._type);
    _buf.put(val._data);
  }

  protected int putSymbol(String name, DBSymbol s) {
    return _putString(name, s.getSymbol(), SYMBOL);
  }

  protected int putString(String name, String s) {
    return _putString(name, s, STRING);
  }

  private int _putString(String name, String s, byte type) {
    int start = _buf.position();
    _put(type, name);
    _putValueString(s);
    return _buf.position() - start;
  }

  protected int putObjectId(String name, ObjectId oid) {
    int start = _buf.position();
    _put(OID, name);
    _buf.putInt(oid._time);
    _buf.putInt(oid._machine);
    _buf.putInt(oid._inc);
    return _buf.position() - start;
  }

  protected int putDBPointer(String name, String ns, ObjectId oid) {
    int start = _buf.position();
    _put(REF, name);

    _putValueString(ns);
    _buf.putInt(oid._time);
    _buf.putInt(oid._machine);
    _buf.putInt(oid._inc);

    return _buf.position() - start;
  }

  protected void putDBRef(String name, DBRefBase ref) {
    _put(OBJECT, name);
    final int sizePos = _buf.position();
    _buf.putInt(0);

    _putObjectField("$ref", ref.getRef());
    _putObjectField("$id", ref.getId());

    _buf.put(EOO);
    _buf.putInt(sizePos, _buf.position() - sizePos);
  }

  private int putDBRegex(String name, DBRegex regex) {

    int start = _buf.position();
    _put(REGEX, name);
    _put(regex.getPattern());

    String options = regex.getOptions();

    TreeMap<Character, Character> sm = new TreeMap<Character, Character>();

    for (int i = 0; i < options.length(); i++) {
      sm.put(options.charAt(i), options.charAt(i));
    }

    StringBuffer sb = new StringBuffer();

    for (char c : sm.keySet()) {
      sb.append(c);
    }

    _put(sb.toString());
    return _buf.position() - start;
  }

  private int putPattern(String name, Pattern p) {
    int start = _buf.position();
    _put(REGEX, name);
    _put(p.pattern());
    _put(patternFlags(p.flags()));
    return _buf.position() - start;
  }

  // ----------------------------------------------

  /** Encodes the type and key. */
  private void _put(byte type, String name) {
    _buf.put(type);
    _put(name);
  }

  void _putValueString(String s) {
    int lenPos = _buf.position();
    _buf.putInt(0); // making space for size
    int strLen = _put(s);
    _buf.putInt(lenPos, strLen);
  }

  int _put(String name) {

    _cbuf.position(0);
    _cbuf.limit(_cbuf.capacity());
    _cbuf.append(name);

    _cbuf.flip();
    final int start = _buf.position();
    _encoder.encode(_cbuf, _buf, false);

    _buf.put((byte) 0);

    return _buf.position() - start;
  }

  boolean _dontRefContains(Object o) {
    if (_dontRef.size() == 0) return false;
    return _dontRef.peek().contains(o);
  }

  private final CharBuffer _cbuf = CharBuffer.allocate(MAX_STRING);
  private final CharsetEncoder _encoder = _utf8.newEncoder();
  private Stack<IdentitySet> _dontRef = new Stack<IdentitySet>();

  private boolean _flipped = false;
  final ByteBuffer _buf;
}
  public static void main(String[] args) throws Throwable {
    final int itrs = Integer.getInteger("iterations", 100000);
    // final int itrs = Integer.getInteger("iterations", 12);
    final int size = Integer.getInteger("size", 2048);
    final int subsize = Integer.getInteger("subsize", 128);
    final int maxchar = Integer.getInteger("maxchar", 128);
    final String regex = System.getProperty("filter");
    final Pattern filter = (regex == null) ? null : Pattern.compile(regex);
    final boolean useSecurityManager = Boolean.getBoolean("SecurityManager");
    if (useSecurityManager) System.setSecurityManager(new PermissiveSecurityManger());
    final Random rnd = new Random();

    String[] csns =
        new String[] {
          "Big5",
          "Johab",
          "EUC_CN",
          "EUC_KR",
          "MS932",
          "MS936",
          "MS949",
          "MS950",
          "GBK",
          "Big5_HKSCS",
          "Big5_HKSCS_2001",
          "Big5_Solaris",
          "MS950_HKSCS",
          "MS950_HKSCS_XP",
          "IBM1364",
          "IBM1381",
          "IBM1383",
          "IBM930",
          "IBM933",
          "IBM935",
          "IBM937",
          "IBM939",
          "IBM942",
          "IBM943",
          "IBM948",
          "IBM949",
          "IBM950",
          "IBM970",
        };

    ArrayList<long[]> sum = new ArrayList<>();

    for (final String csn : csns) {
      final Charset cs = Charset.forName(csn);
      List<Integer> cps = new ArrayList<>(0x4000);
      int off = 0;
      int cp = 0;
      int n = 0;
      CharsetEncoder enc = cs.newEncoder();
      while (cp < 0x10000 && n < cps.size()) {
        if (enc.canEncode((char) cp)) {
          cps.add(cp);
          n++;
        }
        cp++;
      }
      Collections.shuffle(cps);
      char[] ca = new char[cps.size()];
      for (int i = 0; i < cps.size(); i++) ca[i] = (char) (int) cps.get(i);

      System.out.printf("%n--------%s---------%n", csn);
      for (int sz = 8; sz <= 2048; sz *= 2) {
        System.out.printf("   [len=%d]%n", sz);

        final char[] chars = Arrays.copyOf(ca, sz);
        final String str = new String(chars);
        final byte[] bs = str.getBytes(cs);

        Job[] jobs = {
          new Job("String decode: csn") {
            public void work() throws Throwable {
              for (int i = 0; i < itrs; i++) new String(bs, csn);
            }
          },
          new Job("String decode: cs") {
            public void work() throws Throwable {
              for (int i = 0; i < itrs; i++) new String(bs, cs);
            }
          },
          new Job("String encode: csn") {
            public void work() throws Throwable {
              for (int i = 0; i < itrs; i++) str.getBytes(csn);
            }
          },
          new Job("String encode: cs") {
            public void work() throws Throwable {
              for (int i = 0; i < itrs; i++) str.getBytes(cs);
            }
          },
        };
        sum.add(time(jobs));
      }
    }
  }
  /**
   * Returns boolean value from system property or provided function.
   *
   * @param propName System property host.
   * @param dflt Function that returns {@code Boolean}.
   * @return {@code Boolean} value
   */
  public static boolean boolValue(String propName, boolean dflt) {
    String sysProp = getProperty(propName);

    return (sysProp != null && !sysProp.isEmpty()) ? Boolean.getBoolean(sysProp) : dflt;
  }