// Npgsql.NpgsqlCopyOutState.cs
//
// Author:
//     Kalle Hallivuori <kato@iki.fi>
//
//    Copyright (C) 2007 The Npgsql Development Team
//    npgsql-general@gborg.postgresql.org
//    http://gborg.postgresql.org/project/npgsql/projdisplay.php
//
// Permission to use, copy, modify, and distribute this software and its
// documentation for any purpose, without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph and the following two paragraphs appear in all copies.
//
// IN NO EVENT SHALL THE NPGSQL DEVELOPMENT TEAM BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
// DOCUMENTATION, EVEN IF THE NPGSQL DEVELOPMENT TEAM HAS BEEN ADVISED OF
// THE POSSIBILITY OF SUCH DAMAGE.
//
// THE NPGSQL DEVELOPMENT TEAM SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
// ON AN "AS IS" BASIS, AND THE NPGSQL DEVELOPMENT TEAM HAS NO OBLIGATIONS
// TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

using System;
using System.IO;

namespace Npgsql
{
    /// <summary>
    /// Represents an ongoing COPY TO STDOUT operation.
    /// Provides methods to read data from server or end the operation.
    /// </summary>
    internal sealed class NpgsqlCopyOutState : NpgsqlState
    {
        public static readonly NpgsqlCopyOutState Instance = new NpgsqlCopyOutState();

        //private readonly String CLASSNAME = MethodBase.GetCurrentMethod().DeclaringType.Name;

        private NpgsqlCopyFormat _copyFormat = null;

        private NpgsqlCopyOutState()
            : base()
        {
        }

        /// <summary>
        /// Copy format information returned from server.
        /// </summary>
        public override NpgsqlCopyFormat CopyFormat
        {
            get { return _copyFormat; }
        }

        /// <summary>
        /// Called from NpgsqlState.ProcessBackendResponses upon CopyOutResponse.
        /// If CopyStream is already set, it is used to write data received from server, after which the copy ends.
        /// Otherwise CopyStream is set to a readable NpgsqlCopyOutStream that receives data from server.
        /// </summary>
        protected override void StartCopy(NpgsqlConnector context, NpgsqlCopyFormat copyFormat)
        {
            _copyFormat = copyFormat;
            Stream userFeed = context.Mediator.CopyStream;
            if (userFeed == null)
            {
                context.Mediator.CopyStream = new NpgsqlCopyOutStream(context);
            }
            else
            {
                byte[] buf;
                while ((buf = GetCopyData(context)) != null)
                {
                    userFeed.Write(buf, 0, buf.Length);
                }
                userFeed.Close();
            }
        }

        /// <summary>
        /// Called from NpgsqlOutStream.Read to read copy data from server.
        /// </summary>
        public override byte[] GetCopyData(NpgsqlConnector context)
        {
            // polling in COPY would take seconds on Windows
            foreach (IServerResponseObject obj in ProcessBackendResponses(context))
            {
                if (obj is IDisposable)
                {
                    (obj as IDisposable).Dispose();
                }
            }
            return context.Mediator.ReceivedCopyData;
        }
    }
}
