private void PrepareFileInfoForCorrectFile()
{
byte first = Convert.ToByte(m_Stream.ReadByte());
m_Info = new NumberFileInfo()
{
IsInvalid = false,
IsNegative = first == Minus_ASCI
};
m_Info.RealPartPosition = new FileRangeInfo()
{
From = (first == Minus_ASCI || first == Plus_ASCI) ? 1 : 0,
To = m_Stream.Length - 1
};
}
public async Task PrepareFileInfoAsync(bool isFileCorrect)
{
if (m_Stream.Position != 0)
{
m_Stream.Seek(0, SeekOrigin.Begin);
}
if (isFileCorrect)
{
PrepareFileInfoForCorrectFile();
return;
}
m_Info = null;
int readCount;
bool toPositionWasFound = false;
byte[] buffer = new byte[Math.Min(Buffer, m_Stream.Length)];
bool crWasDetectedBefore = false;
long lastNumberIndex = -1;
int? lastZeroIndexFromStart = null;
// Need to Check if file info is ok.
while ((readCount = await m_Stream.ReadAsync(buffer, 0, buffer.Length)) != 0)
{
bool isFirstRead = m_Info == null;
if (buffer.Length > 0 && isFirstRead)
{
var first = buffer[0];
if (first != Plus_ASCI && first != Minus_ASCI && !IsNumber(first))
{
m_Info = new NumberFileInfo()
{
IsInvalid = true
};
break;
}
else
{
m_Info = new NumberFileInfo()
{
IsNegative = first == Minus_ASCI
};
m_Info.RealPartPosition = new FileRangeInfo()
{
From = first == Minus_ASCI || first == Plus_ASCI ? 1 : 0
};
if (IsNumber(first))
{
lastNumberIndex = 0;
}
if (first == Number_Zero)
{
lastZeroIndexFromStart = 0;
}
}
}
byte value;
var streamPosition = m_Stream.Position;
var bufferLength = buffer.Length;
for (int i = isFirstRead ? 1 : 0; i < bufferLength; i++)
{
value = buffer[i];
// ignore cr - can exist before new line
if (value == CR)
{
crWasDetectedBefore = true;
continue;
}
if (lastZeroIndexFromStart.HasValue || (lastNumberIndex == -1))
{
if (value == Number_Zero)
{
lastZeroIndexFromStart = i;
}
else
{
// skip 0
if (lastZeroIndexFromStart.HasValue)
{
m_Info.RealPartPosition.From = lastZeroIndexFromStart.Value + 1;
}
lastZeroIndexFromStart = null;
}
}
// Take real position from begin of the file.
var realPosition = streamPosition - readCount + i;
if (value == NewLine)
{
if (m_Info.RealPartPosition.To == 0)
{
toPositionWasFound = true;
m_Info.RealPartPosition.To = realPosition - (crWasDetectedBefore ? 2 : 1);
}
crWasDetectedBefore = false;
break;
}
else if (!IsNumber(value))
{
m_Info.IsInvalid = true;
break;
}
else
{
lastNumberIndex = realPosition;
}
}
}
if (m_Info.RealPartPosition != null && m_Info.RealPartPosition.To == 0 && !toPositionWasFound)
{
if (lastNumberIndex >= m_Info.RealPartPosition.From)
{
m_Info.RealPartPosition.To = m_Stream.Length - 1;
}
else
{
m_Info.RealPartPosition = null;
}
}
if (m_Info.RealPartPosition == null || m_Info.RealPartPosition.GetLength() <= 0)
{
m_Info.IsInvalid = true;
}
}