/*
 *	Firebird ADO.NET Data provider for .NET and Mono 
 * 
 *	   The contents of this file are subject to the Initial 
 *	   Developer's Public License Version 1.0 (the "License"); 
 *	   you may not use this file except in compliance with the 
 *	   License. You may obtain a copy of the License at 
 *	   http://www.firebirdsql.org/index.php?op=doc&id=idpl
 *
 *	   Software distributed under the License is distributed on 
 *	   an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either 
 *	   express or implied. See the License for the specific 
 *	   language governing rights and limitations under the License.
 * 
 *	Copyright (c) 2002, 2005 Carlos Guzman Alvarez
 *	All Rights Reserved.
 */

using System;
using System.Data;
using System.IO;

using FirebirdSql.Data.Common;

namespace FirebirdSql.Data.Gds
{
	internal sealed class GdsTransaction : ITransaction, IDisposable
	{
		#region Events

		public event TransactionUpdateEventHandler Update;

		#endregion

		#region Fields

		private int					handle;
		private bool				disposed;
		private GdsDatabase			db;
		private TransactionState	state;

		#endregion

		#region Properties

		public int Handle
		{
			get { return this.handle; }
		}

		public TransactionState State
		{
			get { return this.state; }
		}

		#endregion

		#region Constructors

		public GdsTransaction(IDatabase db)
		{
			if (!(db is GdsDatabase))
			{
				throw new ArgumentException("Specified argument is not of GdsDatabase type.");
			}

			this.db		= (GdsDatabase)db;
			this.state	= TransactionState.NoTransaction;

			GC.SuppressFinalize(this);
		}

		#endregion

		#region Finalizer

		~GdsTransaction()
		{
			this.Dispose(false);
		}

		#endregion

		#region IDisposable	methods

		public void Dispose()
		{
			this.Dispose(true);
			GC.SuppressFinalize(this);
		}

		private void Dispose(bool disposing)
		{
			lock (this)
			{
				if (!this.disposed)
				{
					try
					{
						// release any unmanaged resources
						this.Rollback();

						// release any managed resources
						if (disposing)
						{
							this.db		= null;
							this.handle = 0;
							this.state	= TransactionState.NoTransaction;
						}
					}
					finally
					{
						this.disposed = true;
					}
				}
			}
		}

		#endregion

		#region Methods

		public void BeginTransaction(TransactionParameterBuffer tpb)
		{
			lock (this.db)
			{
				if (this.state != TransactionState.NoTransaction)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TrasactionStarting;

				try
				{
					this.db.Send.Write(IscCodes.op_transaction);
					this.db.Send.Write(this.db.Handle);
					this.db.Send.WriteBuffer(tpb.ToArray());
					this.db.Send.Flush();

					this.handle = db.ReadGenericResponse().ObjectHandle;
					this.state = TransactionState.TransactionStarted;

					this.db.TransactionCount++;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		public void Commit()
		{
			lock (this.db)
			{
				if (this.state != TransactionState.TransactionStarted &&
					this.state != TransactionState.TransactionPrepared)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionCommiting;

				try
				{
					this.db.Send.Write(IscCodes.op_commit);
					this.db.Send.Write(this.handle);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.db.TransactionCount--;

					if (this.Update != null)
					{
						this.Update(this, new EventArgs());
					}

					this.state = TransactionState.NoTransaction;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		public void Rollback()
		{
			lock (this.db)
			{
				if (this.state == TransactionState.NoTransaction)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionRollbacking;

				try
				{
					this.db.Send.Write(IscCodes.op_rollback);
					this.db.Send.Write(this.handle);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.db.TransactionCount--;

					if (this.Update != null)
					{
						this.Update(this, new EventArgs());
					}

					this.state = TransactionState.NoTransaction;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		public void CommitRetaining()
		{
			lock (this.db)
			{
				if (this.state != TransactionState.TransactionStarted &&
					this.state != TransactionState.TransactionPrepared)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionCommiting;

				try
				{
					this.db.Send.Write(IscCodes.op_commit_retaining);
					this.db.Send.Write(this.handle);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.state = TransactionState.TransactionStarted;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		public void RollbackRetaining()
		{
			lock (this.db)
			{
				if (this.state != TransactionState.TransactionStarted &&
					this.state != TransactionState.TransactionPrepared)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionRollbacking;

				try
				{
					this.db.Send.Write(IscCodes.op_rollback_retaining);
					this.db.Send.Write(this.handle);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.state = TransactionState.TransactionStarted;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		/*
		public void	Prepare()
		{
			lock (this.db)
			{
				if (this.state != TransactionState.TransactionStarted)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionPreparing;

				try
				{
					this.db.Send.Write(IscCodes.op_prepare);
					this.db.Send.Write(this.handle);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.state = TransactionState.TransactionPrepared;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}

		public void	Prepare(byte[] buffer)
		{
			lock (this.db)
			{
				if (this.state != TransactionState.TransactionStarted)
				{
					throw new IscException(
						IscCodes.isc_arg_gds,
						IscCodes.isc_tra_state,
						this.handle,
						"no valid");
				}

				this.state = TransactionState.TransactionPreparing;

				try
				{
					this.db.Send.Write(IscCodes.op_prepare2);
					this.db.Send.Write(this.handle);
					this.db.Send.WriteBuffer(buffer, buffer.Length);
					this.db.Send.Flush();

					this.db.ReadGenericResponse();

					this.state = TransactionState.TransactionStarted;
				}
				catch (IOException)
				{
					throw new IscException(IscCodes.isc_net_read_err);
				}
			}
		}
		*/

		#endregion
	}
}