"""Module with our own gitdb implementation - it uses the git command"""
from exc import (
					GitCommandError, 
					BadObject
				)

from gitdb.base import (
								OInfo,
								OStream
							)

from gitdb.util import (
							bin_to_hex, 
							hex_to_bin
						)
from gitdb.db import GitDB
from gitdb.db import LooseObjectDB


__all__ = ('GitCmdObjectDB', 'GitDB' )

#class GitCmdObjectDB(CompoundDB, ObjectDBW):
class GitCmdObjectDB(LooseObjectDB):
	"""A database representing the default git object store, which includes loose 
	objects, pack files and an alternates file
	
	It will create objects only in the loose object database.
	:note: for now, we use the git command to do all the lookup, just until he 
		have packs and the other implementations
	"""
	def __init__(self, root_path, git):
		"""Initialize this instance with the root and a git command"""
		super(GitCmdObjectDB, self).__init__(root_path)
		self._git = git
		
	def info(self, sha):
		hexsha, typename, size = self._git.get_object_header(bin_to_hex(sha))
		return OInfo(hex_to_bin(hexsha), typename, size)
		
	def stream(self, sha):
		"""For now, all lookup is done by git itself"""
		hexsha, typename, size, stream = self._git.stream_object_data(bin_to_hex(sha))
		return OStream(hex_to_bin(hexsha), typename, size, stream)
	
	
	# { Interface
	
	def partial_to_complete_sha_hex(self, partial_hexsha):
		""":return: Full binary 20 byte sha from the given partial hexsha
		:raise AmbiguousObjectName:
		:raise BadObject:
		:note: currently we only raise BadObject as git does not communicate 
			AmbiguousObjects separately"""
		try:
			hexsha, typename, size = self._git.get_object_header(partial_hexsha)
			return hex_to_bin(hexsha)
		except (GitCommandError, ValueError):
			raise BadObject(partial_hexsha)
		# END handle exceptions
	
	#} END interface
