import FuseArchive, logging, os, sha
from binascii import hexlify
from FuseArchive.Chunk import Chunk

magic_depth = 5

# This will write out a data block, it will return a key that can get this
# data back later
def save_chunk( chunk ):
    if FuseArchive.magic_profiling:
        return( [ 0, 0 ] )

    logging.debug( "Begin save_chunk, length: %d" % len( chunk ) )
    if FuseArchive.deep_debug:
        logging.debug( "Chunk: %s" + hexlify( chunk ) )

    # Save this hash string, similar to the backuppc algo
    digest = sha.new( chunk ).digest()

    # Write out our chunk
    chars = list( digest )
    logging.debug( chars )

    # We make the hexdigest here, yeah we could just call hexdigest()
    # but we need to essentially do this same thing to reassemble the
    # file anyway
    hexdigest = ''.join( [ "%02x" % ord( x ) for x in chars ] )

    # Subparts just needs the first N chars
    subparts = [ "%02x" % ord( x ) for x in chars[ :magic_depth ] ]

    logging.debug( subparts )
    subpath = '/'.join( subparts )
    logging.debug( "Subpath: " + subpath )

    # Make sure this sub path exists
    nextpart = "./storage"
    for part in subparts:
        nextpart += "/" + part
        if not os.path.exists( nextpart ):
            logging.debug( "Creating subdir: " + nextpart )
            os.mkdir( nextpart )

    # Find a chunk slot
    sub = 0
    while True:
        checkpath = "./storage/%s/%s_%d" % ( subpath, hexdigest, sub )
        logging.debug( "Checking: " + checkpath )
        if os.path.exists( checkpath ):
            # Check if this is our data
            verify = open( checkpath, "rb" )
            verify_contents = verify.read()
            verify.close()

            verify_contents = Chunk.deserialize( verify_contents )
            if verify_contents.chunk == chunk:
                logging.debug( "Found existing block" )
                break
            else:
                logging.debug( "Block exists but is not the same" )
                sub += 1
        else:
            # We found a spot, dump our data here
            logging.debug( "No block here, creating new block" )
            save_chunk = Chunk()
            save_chunk.chunk = chunk
            savechunk = open( checkpath, "wb" )
            savechunk.write( save_chunk.serialize() )
            savechunk.close()
            break

    logging.debug( "Got chunk slot: %d" % sub )
    return( [ digest, sub ] )

# This will return a data block by key that was saved previously
def load_chunk( key ):
    if FuseArchive.magic_profiling:
        return ''

    ( thash, seq ) = key
    logging.debug( "Begin load_chunk" )

    chars = list( thash )
    logging.debug( chars )

    # Todo: make a digest -> path function to share with deflate
    hexdigest = ''.join( [ "%02x" % ord( x ) for x in chars ] )
    logging.debug( "Hash is: %s sub %d" % ( hexdigest, seq ) )
    subparts = [ "%02x" % ord( x ) for x in chars[ :magic_depth ] ]
    subpath = '/'.join( subparts )
    logging.debug( "Subpath: " + subpath )

    subpath += "/%s_%d" % ( hexdigest, seq )

    logging.debug( "Chunk path: " + subpath )

    if os.path.exists( "./storage/" + subpath ):
        logging.debug( "Exporting chunk" )
        readchunk = open( "./storage/" + subpath )
        chunk = Chunk.deserialize( readchunk.read() ).chunk
        readchunk.close()
    else:
        raise IOError

    if FuseArchive.deep_debug:
        logging.debug( "Load-Chunk: %s" + hexlify( chunk ) )

    return chunk