from minidump.constants import MINIDUMP_TYPE
from minidump.exceptions import MinidumpHeaderFlagsException, MinidumpHeaderSignatureMismatchException
import io

# https://msdn.microsoft.com/en-us/library/windows/desktop/ms680378(v=vs.85).aspx
class MinidumpHeader:
	def __init__(self):
		self.Signature = 'PMDM'
		self.Version = None
		self.ImplementationVersion = None
		self.NumberOfStreams = None
		self.StreamDirectoryRva = None
		self.CheckSum = 0
		self.Reserved = 0
		self.TimeDateStamp = 0
		self.Flags = None

	def to_bytes(self):
		t = self.Signature.encode('ascii')
		t += self.Version.to_bytes(2, byteorder = 'little', signed = False)
		t += self.ImplementationVersion.to_bytes(2, byteorder = 'little', signed = False)
		t += self.NumberOfStreams.to_bytes(4, byteorder = 'little', signed = False)
		t += self.StreamDirectoryRva.to_bytes(4, byteorder = 'little', signed = False)
		t += self.CheckSum.to_bytes(4, byteorder = 'little', signed = False)
		t += self.Reserved.to_bytes(4, byteorder = 'little', signed = False)
		t += self.TimeDateStamp.to_bytes(4, byteorder = 'little', signed = False)
		t += self.Flags.value.to_bytes(4, byteorder = 'little', signed = False)

		return t

	@staticmethod
	def parse(buff):
		mh = MinidumpHeader()
		mh.Signature = buff.read(4).decode()[::-1]
		if mh.Signature != 'PMDM':
			raise MinidumpHeaderSignatureMismatchException(mh.Signature)
		mh.Version = int.from_bytes(buff.read(2), byteorder = 'little', signed = False)
		mh.ImplementationVersion = int.from_bytes(buff.read(2), byteorder = 'little', signed = False)
		mh.NumberOfStreams = int.from_bytes(buff.read(4), byteorder = 'little', signed = False)
		mh.StreamDirectoryRva = int.from_bytes(buff.read(4), byteorder = 'little', signed = False)
		mh.CheckSum = int.from_bytes(buff.read(4), byteorder = 'little', signed = False)
		mh.Reserved = int.from_bytes(buff.read(4), byteorder = 'little', signed = False)
		mh.TimeDateStamp = int.from_bytes(buff.read(4), byteorder = 'little', signed = False)
		try:
			mh.Flags = MINIDUMP_TYPE(int.from_bytes(buff.read(4), byteorder = 'little', signed = False))
		except Exception as e:
			raise MinidumpHeaderFlagsException('Could not parse header flags!')

		return mh

	@staticmethod
	async def aparse(abuff):
		adata = await abuff.read(32)
		buff = io.BytesIO(adata)
		return MinidumpHeader.parse(buff)

	def __str__(self):
		t = '== MinidumpHeader ==\n'
		t+= 'Signature: %s\n' % self.Signature
		t+= 'Version: %s\n' % self.Version
		t+= 'ImplementationVersion: %s\n' % self.ImplementationVersion
		t+= 'NumberOfStreams: %s\n' % self.NumberOfStreams
		t+= 'StreamDirectoryRva: %s\n' % self.StreamDirectoryRva
		t+= 'CheckSum: %s\n' % self.CheckSum
		t+= 'Reserved: %s\n' % self.Reserved
		t+= 'TimeDateStamp: %s\n' % self.TimeDateStamp
		t+= 'Flags: %s\n' % self.Flags
		return t