Namespace System
Namespace IO

Class StreamReader
	Inherits TextReader
Public
	Sub StreamReader(path As String)
		init(New FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
	End Sub

	Sub StreamReader(stream As Stream)
		init(stream)
	End Sub

	Override Sub Dispose(disposing As Boolean)
		s.Dispose(disposing)
		size = 0
		cur = 0
		last = 0
	End Sub

	Override Function Peek() As Long
		If cur = last Then
			last = s.Read(buf, 0, size)
			cur = 0
			If last = 0 Then
				Peek = -1
				Exit Function
			End If
		End If
		Peek = buf[cur]
	End Function

	Override Function Read() As Long
		Read = Peek()
		cur++
	End Function

	Override Function Read(buffer As *StrChar, index As Long, count As Long) As Long
		If buffer = 0 Then
		ElseIf index < 0 Then
		ElseIf count < 0 Then
		End If

		Dim n = last - cur
		If count <= n Then
			Read = ReadFromBuffer(buffer, index, count)
			Exit Function
		End If
		Dim p = VarPtr(buffer[index])
		Read = ReadFromBuffer(p, 0, n)
		If Read = count Then 'バッファの中身で足りた場合
			Exit Function
		End If
		p = VarPtr(p[n])
		count -= n
		If count > size Then
			n = (count \ size) * size 'sizeの倍数分だけは直接bufferへ読み込ませる
			Dim read = s.Read(p, 0, n)
			If read = 0 Then 'EOF
				Exit Function
			End If
			p = VarPtr(p[n])
			Read += n
			count -= n
		End If
		last = s.Read(buffer, 0, size)
		cur = 0
		If last = 0 Then 'EOF
			Exit Function
		End If
		Read += ReadFromBuffer(p, 0, Math.Min(last, count))
	End Function

	Override Function ReadLine() As String
		Dim sb = New Text.StringBuilder(256)
		Do
			Dim ch = Read()
			If ch = &h0D Then
				If Peek() = &h0A Then
					Read() 'CR LFの場合
				End If
				Exit Do
			End If
			Select Case ch
				Case -1 'EOF
					Exit Do
				Case &h0A 'LF
					Exit Do
				Case &h0B 'VT
					Exit Do
				Case &h0C 'FF
					Exit Do
				Case &h0D 'CR
					Exit Do
'				Case &h85 'NEL
'					Exit Do
'				Case &h2028 'LS
'					Exit Do
'				Case &h2029 'PS
'					Exit Do
			End Select
			sb.Append(ch As StrChar) 'ToDo キャスト不要にすべきというチケットを書くこと
		Loop
		ReadLine = sb.ToString
	End Function

	Override Function ReadToEnd() As String
	End Function

Private
	Sub init(str As Stream)
		s = str
		size = 4096
		last = 0
		cur = 0
		buf = GC_malloc(size)
	End Sub

	/**
	@brief バッファの中身から読み取る。
	文字数が足りなくても、元のストリームまで読みには行かない。
	*/
	Function ReadFromBuffer(p As *StrChar, index As Long, count As Long) As Long
		memcpy(VarPtr(p[index]), VarPtr(buf[cur]), count * SizeOf (StrChar))
		cur += count
		ReadFromBuffer = count
	End Function

	s As Stream
	size As Long
	cur As Long
	last As Long '中身の終わり
	buf As *Byte '暫定
End Class

End Namespace
End Namespace