import fuse, os, logging, errno
from ChunkFile import ChunkFile

if not hasattr(fuse, '__version__'):
    raise RuntimeError, \
        "your fuse-py doesn't know of fuse.__version__, probably it's too old."

fuse.fuse_python_api = (0, 2)
fuse.feature_assert('stateful_files', 'has_init')

class FileSystem(fuse.Fuse):

    def __init__(self, *args, **kw):

        fuse.Fuse.__init__(self, *args, **kw)
        self.root = None

    # Fix getattr and fgetattr to?
    def getattr(self, path):
        treefile = "./tree" + path

        if os.path.isfile( treefile ):
            logging.debug( "Delegating getattr to File for " + path )

            # Check in the dirty cache first (to handle lseek and the
            # relatively broken implmentation in fuse/python)
            f = ChunkFile.get_dirty_file( path )
            if f:
                logging.info( "WORKAROUND: lseek appears to do a gettattr if whence is SEEK_END, using dirty cache object" )
                stats = f.fgetattr()
                # no release, it's still being used
            else:
                f = ChunkFile( path, os.O_RDONLY, 0 )
                stats = f.fgetattr()
                f.release( 0 )
        else:
            logging.debug( "Using os.lstat to get stats for %s" % path )
            stats = os.lstat( treefile )

        return stats

    def readlink(self, path):
        return os.readlink("./tree" + path)

    def readdir(self, path, offset):
        for e in os.listdir("./tree" + path):
            yield fuse.Direntry(e)

    def unlink(self, path):
        # Ask our file to release it's chunks
        f = ChunkFile( path, os.O_RDWR, 0 )
        f.pre_unlink()
        f.release( 0 )
        os.unlink("./tree" + path)

    def rmdir(self, path):
        os.rmdir("./tree" + path)

    def symlink(self, path, path1):
        os.symlink(path, "./tree" + path1)

    def rename(self, path, path1):
        os.rename("./tree" + path, "./tree" + path1)

    def link(self, path, path1):
        os.link("./tree" + path, "./tree" + path1)

    def chmod(self, path, mode):
        os.chmod("./tree" + path, mode)

    def chown(self, path, user, group):
        os.chown("./tree" + path, user, group)

    def truncate(self, path, len):
        # Truncate using the ftruncate on the file
        logging.debug( "Using FuseArchiveFile to truncate %s to %d" % ( path, len) )
        f = ChunkFile( path, os.O_RDWR, 0 )
        f.ftruncate(len)
        f.release( 0 )

    def mknod(self, path, mode, dev):
        os.mknod("./tree" + path, mode, dev)

    def mkdir(self, path, mode):
        os.mkdir("./tree" + path, mode)

    def utime(self, path, times):
        os.utime("./tree" + path, times)

#    The following utimens method would do the same as the above utime method.
#    We can't make it better though as the Python stdlib doesn't know of
#    subsecond preciseness in acces/modify times.
#  
#    def utimens(self, path, ts_acc, ts_mod):
#      os.utime("." + path, (ts_acc.tv_sec, ts_mod.tv_sec))

    def access(self, path, mode):
        if not os.access("./tree" + path, mode):
            return -errno.EACCES

#    This is how we could add stub extended attribute handlers...
#    (We can't have ones which aptly delegate requests to the underlying fs
#    because Python lacks a standard xattr interface.)
#
#    def getxattr(self, path, name, size):
#        val = name.swapcase() + '@' + path
#        if size == 0:
#            # We are asked for size of the value.
#            return len(val)
#        return val
#
#    def listxattr(self, path, size):
#        # We use the "user" namespace to please XFS utils
#        aa = ["user." + a for a in ("foo", "bar")]
#        if size == 0:
#            # We are asked for size of the attr list, ie. joint size of attrs
#            # plus null separators.
#            return len("".join(aa)) + len(aa)
#        return aa

    def statfs(self):
        """
        Should return an object with statvfs attributes (f_bsize, f_frsize...).
        Eg., the return value of os.statvfs() is such a thing (since py 2.2).
        If you are not reusing an existing statvfs object, start with
        fuse.StatVFS(), and define the attributes.

        To provide usable information (ie., you want sensible df(1)
        output, you are suggested to specify the following attributes:

            - f_bsize - preferred size of file blocks, in bytes
            - f_frsize - fundamental size of file blcoks, in bytes
                [if you have no idea, use the same as blocksize]
            - f_blocks - total number of blocks in the filesystem
            - f_bfree - number of free blocks
            - f_files - total number of file inodes
            - f_ffree - nunber of free file inodes
        """

        return os.statvfs(".")

    def fsinit(self):
        os.chdir(self.root)

    def main(self, *a, **kw):

        self.file_class = ChunkFile

        # This is where fragments go
        if not os.path.exists( 'storage' ):
            os.mkdir( 'storage' )

        # This is where the real files exist
        if not os.path.exists( 'tree' ):
            os.mkdir( 'tree' )

        return fuse.Fuse.main(self, *a, **kw)