"""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
