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/*
 *  streams library
 *
 *  Copyright (C) 2011-2014 by Christian Bockermann, Hendrik Blom
 * 
 *  streams is a library, API and runtime environment for processing high
 *  volume data streams. It is composed of three submodules "stream-api",
 *  "stream-core" and "stream-runtime".
 *
 *  The streams library (and its submodules) is free software: you can 
 *  redistribute it and/or modify it under the terms of the 
 *  GNU Affero General Public License as published by the Free Software 
 *  Foundation, either version 3 of the License, or (at your option) any 
 *  later version.
 *
 *  The stream.ai library (and its submodules) is distributed in the hope
 *  that it will be useful, but WITHOUT ANY WARRANTY; without even the implied 
 *  warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package stream.data;

import java.io.Serializable;
import java.math.BigInteger;
import java.util.UUID;

/**
 * This class implements a sequence element which is internally represented as a
 * chunk of bytes (byte[] array) with ascending significance.
 * 
 * @author Christian Bockermann <[email protected]>
 * 
 */
public final class SequenceID implements Serializable, Comparable {

	/** The unique class ID */
	private static final long serialVersionUID = -5395865079744504092L;

	final static int OVERFLOW = 256; // Byte.MAX_VALUE;
	private Integer digits = 1;
	private byte[] value = new byte[1];

	public SequenceID() {
		this(8);
	}

	public SequenceID(int bytes) {
		value = new byte[bytes];
		for (int i = 0; i < value.length; i++) {
			value[i] = 0;
		}

		digits = value.length;
	}

	public SequenceID(byte[] value) {
		this.value = value;
		this.value = new byte[value.length];
		for (int i = 0; i < value.length; i++) {
			this.value[i] = value[i];
		}
		digits = this.value.length;
	}

	public synchronized SequenceID nextValue() {
		return new SequenceID(value).increment();
	}

	public SequenceID increment() {
		synchronized (this) {
			for (int d = 0; d < value.length; d++) {

				if (((int) value[d] & 0xff) + 1 < OVERFLOW) {
					value[d]++;
					return this;
				} else {

					value[d] = 0;
					if (d + 1 == value.length) {

						// append a new digit '0' to the counters...
						byte[] nv = new byte[digits + 1];
						for (int i = 0; i < digits; i++) {
							nv[i] = 0;
						}

						value = nv;
						value[digits] = 1; // the value of the newly created
											// digit...
						digits = value.length;
					}
				}
			}

			value[0]++;
		}

		return this;
	}

	public SequenceID getAndIncrement() {
		SequenceID val = new SequenceID(value);
		increment();
		return val;
	}

	public byte[] value() {

		synchronized (this) {
			byte[] vals = new byte[value.length];
			for (int i = 0; i < vals.length; i++) {
				vals[i] = value[i];
			}
			return vals;
		}
	}

	public BigInteger asBigInteger() {
		return new BigInteger(value);
	}

	public UUID uuid() {
		return UUID.nameUUIDFromBytes(value);
	}

	public SequenceID advance(byte steps) {

		for (byte l = 0; l < steps - 1; l++) {
			nextValue();
		}

		return nextValue();
	}

	/**
	 * @see java.lang.Comparable#compareTo(java.lang.Object)
	 */
	@Override
	public int compareTo(SequenceID other) {

		if (this == other)
			return 0;

		if (this.value.length == other.value.length) {

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

				if (value[i] < other.value[i])
					return -1;

				if (value[i] > other.value[i])
					return 1;
			}

		} else {
			return this.digits.compareTo(other.digits);
		}

		return 0;
	}

	public String toString() {
		StringBuilder b = new StringBuilder("0x");
		boolean foundNonZero = false;
		for (int i = digits; i > 0; i--) {
			int val = ((int) value[i - 1]) & 0xff;
			foundNonZero = foundNonZero || val > 0;
			if (foundNonZero || i == 1)
				b.append(Integer.toHexString(val));
			// if (i > 1)
			// b.append(":");
		}
		return b.toString();
	}

	public static SequenceID parseValue(String str) {
		String[] tok = str.split("\\.");
		byte[] digits = new byte[tok.length];
		for (int i = tok.length; i >= 0; i--) {
			digits[tok.length - i] = Byte.parseByte(tok[i]);
		}

		return new SequenceID(digits);
	}

	public boolean equals(Object o) {
		if (o == this)
			return true;

		if (o instanceof SequenceID) {
			return 0 == this.compareTo((SequenceID) o);
		}

		return false;
	}
}