# Copyright (C) 2005, 2006, 2008, 2009, 2010 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""A store that keeps the full text of every version.

This store keeps uncompressed versions of the full text. It does not
do any sort of delta compression.
"""

import gzip
import os
from cStringIO import StringIO

from bzrlib import osutils
from bzrlib.errors import BzrError, NoSuchFile, FileExists
import bzrlib.store
from bzrlib.trace import mutter



class TextStore(bzrlib.store.TransportStore):
    """Store that holds files indexed by unique names.

    Files can be added, but not modified once they are in.  Typically
    the hash is used as the name, or something else known to be unique,
    such as a UUID.

    Files are stored uncompressed, with no delta compression.
    """

    def _add_compressed(self, fn, f):
        from cStringIO import StringIO
        from bzrlib.osutils import pumpfile

        if isinstance(f, basestring):
            f = StringIO(f)

        sio = StringIO()
        gf = gzip.GzipFile(mode='wb', fileobj=sio)
        # if pumpfile handles files that don't fit in ram,
        # so will this function
        pumpfile(f, gf)
        gf.close()
        sio.seek(0)
        self._try_put(fn, sio)

    def _add(self, fn, f):
        if self._compressed:
            self._add_compressed(fn, f)
        else:
            self._try_put(fn, f)

    def _try_put(self, fn, f):
        try:
            self._transport.put_file(fn, f, mode=self._file_mode)
        except NoSuchFile:
            if not self._prefixed:
                raise
            try:
                self._transport.mkdir(os.path.dirname(fn), mode=self._dir_mode)
            except FileExists:
                pass
            self._transport.put_file(fn, f, mode=self._file_mode)

    def _get(self, fn):
        if fn.endswith('.gz'):
            return self._get_compressed(fn)
        else:
            return self._transport.get(fn)

    def _copy_one(self, fileid, suffix, other, pb):
        # TODO: Once the copy_to interface is improved to allow a source
        #       and destination targets, then we can always do the copy
        #       as long as other is a TextStore
        if not (isinstance(other, TextStore)
            and other._prefixed == self._prefixed):
            return super(TextStore, self)._copy_one(fileid, suffix, other, pb)

        mutter('_copy_one: %r, %r', fileid, suffix)
        path = other._get_name(fileid, suffix)
        if path is None:
            raise KeyError(fileid + '-' + str(suffix))

        try:
            result = other._transport.copy_to([path], self._transport,
                                              mode=self._file_mode)
        except NoSuchFile:
            if not self._prefixed:
                raise
            try:
                self._transport.mkdir(osutils.dirname(path), mode=self._dir_mode)
            except FileExists:
                pass
            result = other._transport.copy_to([path], self._transport,
                                              mode=self._file_mode)

        if result != 1:
            raise BzrError('Unable to copy file: %r' % (path,))

    def _get_compressed(self, filename):
        """Returns a file reading from a particular entry."""
        f = self._transport.get(filename)
        # gzip.GzipFile.read() requires a tell() function
        # but some transports return objects that cannot seek
        # so buffer them in a StringIO instead
        if getattr(f, 'tell', None) is not None:
            return gzip.GzipFile(mode='rb', fileobj=f)
        try:
            from cStringIO import StringIO
            sio = StringIO(f.read())
            return gzip.GzipFile(mode='rb', fileobj=sio)
        finally:
            f.close()
