using System;

using System.IO;

using System.Threading;

using System.Threading.Tasks;

using Npgsql.BackendMessages;

using Npgsql.PostgresTypes;

using Npgsql.TypeHandling;

using Npgsql.TypeMapping;

using NpgsqlTypes;

namespace Npgsql.TypeHandlers

{

#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member

[TypeMapping("lquery", NpgsqlDbType.LQuery)]

class LQueryHandlerFactory : NpgsqlTypeHandlerFactory<string>

{

public override NpgsqlTypeHandler<string> Create(PostgresType postgresType, NpgsqlConnection conn)

=> new LQueryHandler(postgresType, conn);

}

/// <summary>

/// LQuery binary encoding is a simple UTF8 string, but prepended with a version number.

/// </summary>

public class LQueryHandler : TextHandler

{

/// <summary>

/// Prepended to the string in the wire encoding

/// </summary>

const byte LQueryProtocolVersion = 1;

internal override bool PreferTextWrite => false;

protected internal LQueryHandler(PostgresType postgresType, NpgsqlConnection connection)

: base(postgresType, connection) {}

#region Write

public override int ValidateAndGetLength(string value, ref NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter) =>

base.ValidateAndGetLength(value, ref lengthCache, parameter) + 1;

public override int ValidateAndGetLength(char[] value, ref NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter) =>

base.ValidateAndGetLength(value, ref lengthCache, parameter) + 1;

public override int ValidateAndGetLength(ArraySegment<char> value, ref NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter) =>

base.ValidateAndGetLength(value, ref lengthCache, parameter) + 1;

public override async Task Write(string value, NpgsqlWriteBuffer buf, NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter, bool async, CancellationToken cancellationToken = default)

{

if (buf.WriteSpaceLeft < 1)

await buf.Flush(async, cancellationToken);

buf.WriteByte(LQueryProtocolVersion);

await base.Write(value, buf, lengthCache, parameter, async, cancellationToken);

}

public override async Task Write(char[] value, NpgsqlWriteBuffer buf, NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter, bool async, CancellationToken cancellationToken = default)

{

if (buf.WriteSpaceLeft < 1)

await buf.Flush(async, cancellationToken);

buf.WriteByte(LQueryProtocolVersion);

await base.Write(value, buf, lengthCache, parameter, async, cancellationToken);

}

public override async Task Write(ArraySegment<char> value, NpgsqlWriteBuffer buf, NpgsqlLengthCache? lengthCache, NpgsqlParameter? parameter, bool async, CancellationToken cancellationToken = default)

{

if (buf.WriteSpaceLeft < 1)

await buf.Flush(async, cancellationToken);

buf.WriteByte(LQueryProtocolVersion);

await base.Write(value, buf, lengthCache, parameter, async, cancellationToken);

}

#endregion

#region Read

public override async ValueTask<string> Read(NpgsqlReadBuffer buf, int len, bool async, FieldDescription? fieldDescription = null)

{

await buf.Ensure(1, async);

var version = buf.ReadByte();

if (version != LQueryProtocolVersion)

throw new NotSupportedException($"Don't know how to decode lquery with wire format {version}, your connection is now broken");

return await base.Read(buf, len - 1, async, fieldDescription);

}

#endregion

public override TextReader GetTextReader(Stream stream)

{

var version = stream.ReadByte();

if (version != LQueryProtocolVersion)

throw new NpgsqlException($"Don't know how to decode lquery with wire format {version}, your connection is now broken");

return base.GetTextReader(stream);

}

}

}