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JDBC Driver for Google Cloud Spanner
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/*-------------------------------------------------------------------------
*
* Copyright (c) 2009-2014, PostgreSQL Global Development Group
*
*-------------------------------------------------------------------------
*/

package nl.topicus.jdbc.xa;

import java.util.Arrays;

import javax.transaction.xa.Xid;

import nl.topicus.jdbc.util.Base64;

public class RecoveredXid implements Xid
{
	int formatId;
	byte[] globalTransactionId;
	byte[] branchQualifier;

	@Override
	public int getFormatId()
	{
		return formatId;
	}

	@Override
	public byte[] getGlobalTransactionId()
	{
		return globalTransactionId;
	}

	@Override
	public byte[] getBranchQualifier()
	{
		return branchQualifier;
	}

	@Override
	public int hashCode()
	{
		final int prime = 31;
		int result = 1;
		result = prime * result + Arrays.hashCode(branchQualifier);
		result = prime * result + formatId;
		result = prime * result + Arrays.hashCode(globalTransactionId);
		return result;
	}

	@Override
	public boolean equals(Object o)
	{
		if (o == this)
		{
			// optimization for the common case.
			return true;
		}

		if (!(o instanceof Xid))
		{
			return false;
		}

		Xid other = (Xid) o;
		if (other.getFormatId() != formatId)
		{
			return false;
		}
		if (!Arrays.equals(globalTransactionId, other.getGlobalTransactionId()))
		{
			return false;
		}
		return Arrays.equals(branchQualifier, other.getBranchQualifier());
	}

	/**
	 * This is for debugging purposes only
	 */
	@Override
	public String toString()
	{
		return xidToString(this);
	}

	// --- Routines for converting xid to string and back.

	public static String xidToString(Xid xid)
	{
		return xid.getFormatId() + "_" + Base64.encodeBytes(xid.getGlobalTransactionId(), Base64.DONT_BREAK_LINES) + "_"
				+ Base64.encodeBytes(xid.getBranchQualifier(), Base64.DONT_BREAK_LINES);
	}

	/**
	 * @param s
	 *            The string to convert
	 * @return recovered xid, or null if s does not represent a valid xid
	 *         encoded by the driver.
	 */
	public static Xid stringToXid(String s)
	{
		RecoveredXid xid = new RecoveredXid();

		int a = s.indexOf('_');
		int b = s.lastIndexOf('_');

		if (a == b)
		{
			// this also catches the case a == b == -1.
			return null;
		}

		try
		{
			xid.formatId = Integer.parseInt(s.substring(0, a));
			xid.globalTransactionId = Base64.decode(s.substring(a + 1, b));
			xid.branchQualifier = Base64.decode(s.substring(b + 1));

			if (xid.globalTransactionId == null || xid.branchQualifier == null)
			{
				return null;
			}
		}
		catch (Exception ex)
		{
			return null; // Doesn't seem to be an xid generated by this driver.
		}

		return xid;
	}
}