# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4 -*-
#
# Copyright 2002 Ben Escoto <ben@emerose.org>
# Copyright 2007 Kenneth Loafman <kenneth@loafman.com>
#
# This file is part of duplicity.
#
# Duplicity 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.
#
# Duplicity 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 duplicity; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

"""Functions for patching of directories"""

import re

from duplicity import tarfile
from duplicity import librsync
from duplicity import log
from duplicity import diffdir
from duplicity import misc
from duplicity import selection
from duplicity import util
from duplicity.path import *
from duplicity.lazy import *

class PatchDirException(Exception):
    pass


def Patch(base_path, difftar_fileobj):
    """Patch given base_path and file object containing delta"""
    diff_tarfile = tarfile.TarFile("arbitrary", "r", difftar_fileobj)
    patch_diff_tarfile(base_path, diff_tarfile)
    assert not difftar_fileobj.close()

def Patch_from_iter(base_path, fileobj_iter, restrict_index = ()):
    """Patch given base_path and iterator of delta file objects"""
    diff_tarfile = TarFile_FromFileobjs(fileobj_iter)
    patch_diff_tarfile(base_path, diff_tarfile, restrict_index)

def patch_diff_tarfile(base_path, diff_tarfile, restrict_index = ()):
    """Patch given Path object using delta tarfile (as in tarfile.TarFile)

    If restrict_index is set, ignore any deltas in diff_tarfile that
    don't start with restrict_index.

    """
    if base_path.exists():
        path_iter = selection.Select(base_path).set_iter()
    else:
        path_iter = empty_iter() # probably untarring full backup

    diff_path_iter = difftar2path_iter(diff_tarfile)
    if restrict_index:
        diff_path_iter = filter_path_iter(diff_path_iter, restrict_index)
    collated = diffdir.collate2iters(path_iter, diff_path_iter)

    ITR = IterTreeReducer(PathPatcher, [base_path])
    for basis_path, diff_ropath in collated:
        if basis_path:
            log.Info(_("Patching %s") % (basis_path.get_relative_path(),),
                     log.InfoCode.patch_file_patching,
                     util.escape(basis_path.get_relative_path()))
            ITR(basis_path.index, basis_path, diff_ropath)
        else:
            log.Info(_("Patching %s") % (diff_ropath.get_relative_path(),),
                     log.InfoCode.patch_file_patching,
                     util.escape(diff_ropath.get_relative_path()))
            ITR(diff_ropath.index, basis_path, diff_ropath)
    ITR.Finish()
    base_path.setdata()

def empty_iter():
    if 0:
        yield 1 # this never happens, but fools into generator treatment

def filter_path_iter(path_iter, index):
    """Rewrite path elements of path_iter so they start with index

    Discard any that doesn't start with index, and remove the index
    prefix from the rest.

    """
    assert isinstance(index, tuple) and index, index
    l = len(index)
    for path in path_iter:
        if path.index[:l] == index:
            path.index = path.index[l:]
            yield path

def difftar2path_iter(diff_tarfile):
    """Turn file-like difftarobj into iterator of ROPaths"""
    tar_iter = iter(diff_tarfile)
    multivol_fileobj = None

    # The next tar_info is stored in this one element list so
    # Multivol_Filelike below can update it.  Any StopIterations will
    # be passed upwards.
    tarinfo_list = [tar_iter.next()]

    while 1:
        # This section relevant when a multivol diff is last in tar
        if not tarinfo_list[0]:
            raise StopIteration
        if multivol_fileobj and not multivol_fileobj.at_end:
            multivol_fileobj.close() # aborting in middle of multivol
            continue

        index, difftype, multivol = get_index_from_tarinfo(tarinfo_list[0])
        ropath = ROPath(index)
        ropath.init_from_tarinfo(tarinfo_list[0])
        ropath.difftype = difftype
        if difftype == "deleted":
            ropath.type = None
        elif ropath.isreg():
            if multivol:
                multivol_fileobj = Multivol_Filelike(diff_tarfile, tar_iter,
                                                     tarinfo_list, index)
                ropath.setfileobj(multivol_fileobj)
                yield ropath
                continue # Multivol_Filelike will reset tarinfo_list
            else:
                ropath.setfileobj(diff_tarfile.extractfile(tarinfo_list[0]))
        yield ropath
        tarinfo_list[0] = tar_iter.next()

def get_index_from_tarinfo(tarinfo):
    """Return (index, difftype, multivol) pair from tarinfo object"""
    for prefix in ["snapshot/", "diff/", "deleted/",
                   "multivol_diff/", "multivol_snapshot/"]:
        if tarinfo.name.startswith(prefix):
            name = tarinfo.name[len(prefix):] # strip prefix
            if prefix.startswith("multivol"):
                if prefix == "multivol_diff/":
                    difftype = "diff"
                else:
                    difftype = "snapshot"
                multivol = 1
                name, num_subs = \
                      re.subn("(?s)^multivol_(diff|snapshot)/(.*)/[0-9]+$",
                              "\\2", tarinfo.name)
                if num_subs != 1:
                    raise PatchDirException("Unrecognized diff entry %s" %
                                            (tarinfo.name,))
            else:
                difftype = prefix[:-1] # strip trailing /
                name = tarinfo.name[len(prefix):]
                if name.endswith("/"):
                    name = name[:-1] # strip trailing /'s
                multivol = 0
            break
    else:
        raise PatchDirException("Unrecognized diff entry %s" %
                                 (tarinfo.name,))
    if name == "." or name == "":
        index = ()
    else:
        index = tuple(name.split("/"))
        if '..' in index:
            raise PatchDirException("Tar entry %s contains '..'.  Security "
                                    "violation" % (tarinfo.name,))
    return (index, difftype, multivol)


class Multivol_Filelike:
    """Emulate a file like object from multivols

    Maintains a buffer about the size of a volume.  When it is read()
    to the end, pull in more volumes as desired.

    """
    def __init__(self, tf, tar_iter, tarinfo_list, index):
        """Initializer.  tf is TarFile obj, tarinfo is first tarinfo"""
        self.tf, self.tar_iter = tf, tar_iter
        self.tarinfo_list = tarinfo_list # must store as list for write access
        self.index = index
        self.buffer = ""
        self.at_end = 0

    def read(self, length = -1):
        """Read length bytes from file"""
        if length < 0:
            while self.addtobuffer():
                pass
            real_len = len(self.buffer)
        else:
            while len(self.buffer) < length:
                if not self.addtobuffer():
                    break
            real_len = min(len(self.buffer), length)

        result = self.buffer[:real_len]
        self.buffer = self.buffer[real_len:]
        return result

    def addtobuffer(self):
        """Add next chunk to buffer"""
        if self.at_end:
            return None
        index, difftype, multivol = get_index_from_tarinfo(
            self.tarinfo_list[0])
        if not multivol or index != self.index:
            # we've moved on
            # the following communicates next tarinfo to difftar2path_iter
            self.at_end = 1
            return None

        fp = self.tf.extractfile(self.tarinfo_list[0])
        self.buffer += fp.read()
        fp.close()

        try:
            self.tarinfo_list[0] = self.tar_iter.next()
        except StopIteration:
            self.tarinfo_list[0] = None
            self.at_end = 1
            return None
        return 1

    def close(self):
        """If not at end, read remaining data"""
        if not self.at_end:
            while 1:
                self.buffer = ""
                if not self.addtobuffer():
                    break
        self.at_end = 1


class PathPatcher(ITRBranch):
    """Used by DirPatch, process the given basis and diff"""
    def __init__(self, base_path):
        """Set base_path, Path of root of tree"""
        self.base_path = base_path
        self.dir_diff_ropath = None

    def start_process(self, index, basis_path, diff_ropath):
        """Start processing when diff_ropath is a directory"""
        if not (diff_ropath and diff_ropath.isdir()):
            assert index == (), str(index) # should only happen for first elem
            self.fast_process(index, basis_path, diff_ropath)
            return

        if not basis_path:
            basis_path = self.base_path.new_index(index)
            assert not basis_path.exists()
            basis_path.mkdir() # Need place for later files to go into
        elif not basis_path.isdir():
            basis_path.delete()
            basis_path.mkdir()
        self.dir_basis_path = basis_path
        self.dir_diff_ropath = diff_ropath

    def end_process(self):
        """Copy directory permissions when leaving tree"""
        if self.dir_diff_ropath:
            self.dir_diff_ropath.copy_attribs(self.dir_basis_path)

    def can_fast_process(self, index, basis_path, diff_ropath):
        """No need to recurse if diff_ropath isn't a directory"""
        return not (diff_ropath and diff_ropath.isdir())

    def fast_process(self, index, basis_path, diff_ropath):
        """For use when neither is a directory"""
        if not diff_ropath:
            return # no change
        elif not basis_path:
            if diff_ropath.difftype == "deleted":
                pass # already deleted
            else:
                # just copy snapshot over
                diff_ropath.copy(self.base_path.new_index(index))
        elif diff_ropath.difftype == "deleted":
            if basis_path.isdir():
                basis_path.deltree()
            else:
                basis_path.delete()
        elif not basis_path.isreg():
            if basis_path.isdir():
                basis_path.deltree()
            else:
                basis_path.delete()
            diff_ropath.copy(basis_path)
        else:
            assert diff_ropath.difftype == "diff", diff_ropath.difftype
            basis_path.patch_with_attribs(diff_ropath)


class TarFile_FromFileobjs:
    """Like a tarfile.TarFile iterator, but read from multiple fileobjs"""
    def __init__(self, fileobj_iter):
        """Make new tarinfo iterator

        fileobj_iter should be an iterator of file objects opened for
        reading.  They will be closed at end of reading.

        """
        self.fileobj_iter = fileobj_iter
        self.tarfile, self.tar_iter = None, None
        self.current_fp = None

    def __iter__(self):
        return self

    def set_tarfile(self):
        """Set tarfile from next file object, or raise StopIteration"""
        if self.current_fp:
            assert not self.current_fp.close()
        self.current_fp = self.fileobj_iter.next()
        self.tarfile = tarfile.TarFile("arbitrary", "r", self.current_fp)
        self.tar_iter = iter(self.tarfile)

    def next(self):
        if not self.tarfile:
            self.set_tarfile()
        try:
            return self.tar_iter.next()
        except StopIteration:
            assert not self.tarfile.close()
            self.set_tarfile()
            return self.tar_iter.next()

    def extractfile(self, tarinfo):
        """Return data associated with given tarinfo"""
        return self.tarfile.extractfile(tarinfo)


def collate_iters(iter_list):
    """Collate iterators by index

    Input is a list of n iterators each of which must iterate elements
    with an index attribute.  The elements must come out in increasing
    order, and the index should be a tuple itself.

    The output is an iterator which yields tuples where all elements
    in the tuple have the same index, and the tuple has n elements in
    it.  If any iterator lacks an element with that index, the tuple
    will have None in that spot.

    """
    # overflow[i] means that iter_list[i] has been exhausted
    # elems[i] is None means that it is time to replenish it.
    iter_num = len(iter_list)
    if iter_num == 2:
        return diffdir.collate2iters(iter_list[0], iter_list[1])
    overflow = [None] * iter_num
    elems = overflow[:]

    def setrorps(overflow, elems):
        """Set the overflow and rorps list"""
        for i in range(iter_num):
            if not overflow[i] and elems[i] is None:
                try:
                    elems[i] = iter_list[i].next()
                except StopIteration:
                    overflow[i] = 1
                    elems[i] = None

    def getleastindex(elems):
        """Return the first index in elems, assuming elems isn't empty"""
        return min(map(lambda elem: elem.index, filter(lambda x: x, elems)))

    def yield_tuples(iter_num, overflow, elems):
        while 1:
            setrorps(overflow, elems)
            if not None in overflow:
                break

            index = getleastindex(elems)
            yieldval = []
            for i in range(iter_num):
                if elems[i] and elems[i].index == index:
                    yieldval.append(elems[i])
                    elems[i] = None
                else:
                    yieldval.append(None)
            yield tuple(yieldval)
    return yield_tuples(iter_num, overflow, elems)

class IndexedTuple:
    """Like a tuple, but has .index (used previously by collate_iters)"""
    def __init__(self, index, sequence):
        self.index = index
        self.data = tuple(sequence)

    def __len__(self):
        return len(self.data)

    def __getitem__(self, key):
        """This only works for numerical keys (easier this way)"""
        return self.data[key]

    def __lt__(self, other):
        return self.__cmp__(other) == -1
    def __le__(self, other):
        return self.__cmp__(other) != 1
    def __ne__(self, other):
        return not self.__eq__(other)
    def __gt__(self, other):
        return self.__cmp__(other) == 1
    def __ge__(self, other):
        return self.__cmp__(other) != -1

    def __cmp__(self, other):
        assert isinstance(other, IndexedTuple)
        if self.index < other.index:
            return -1
        elif self.index == other.index:
            return 0
        else:
            return 1

    def __eq__(self, other):
        if isinstance(other, IndexedTuple):
            return self.index == other.index and self.data == other.data
        elif type(other) is types.TupleType:
            return self.data == other
        else:
            return None

    def __str__(self):
        return  "(%s).%s" % (", ".join(map(str, self.data)), self.index)

def normalize_ps(patch_sequence):
    """Given an sequence of ROPath deltas, remove blank and unnecessary

    The sequence is assumed to be in patch order (later patches apply
    to earlier ones).  A patch is unnecessary if a later one doesn't
    require it (for instance, any patches before a "delete" are
    unnecessary).

    """
    result_list = []
    i = len(patch_sequence)-1
    while i >= 0:
        delta = patch_sequence[i]
        if delta is not None:
            # skip blank entries
            result_list.insert(0, delta)
            if delta.difftype != "diff":
                break
        i -= 1
    return result_list

def patch_seq2ropath(patch_seq):
    """Apply the patches in patch_seq, return single ropath"""
    first = patch_seq[0]
    assert first.difftype != "diff", patch_seq
    if not first.isreg():
        # No need to bother with data if not regular file
        assert len(patch_seq) == 1, len(patch_seq)
        return first.get_ropath()

    current_file = first.open("rb")

    for delta_ropath in patch_seq[1:]:
        assert delta_ropath.difftype == "diff", delta_ropath.difftype
        if not isinstance(current_file, file):
            # librsync needs true file
            tempfp = os.tmpfile()
            misc.copyfileobj(current_file, tempfp)
            assert not current_file.close()
            tempfp.seek(0)
            current_file = tempfp
        current_file = librsync.PatchedFile(current_file,
                                            delta_ropath.open("rb"))
    result = patch_seq[-1].get_ropath()
    result.setfileobj(current_file)
    return result

def integrate_patch_iters(iter_list):
    """Combine a list of iterators of ropath patches

    The iter_list should be sorted in patch order, and the elements in
    each iter_list need to be orderd by index.  The output will be an
    iterator of the final ROPaths in index order.

    """
    collated = collate_iters(iter_list)
    for patch_seq in collated:
        final_ropath = patch_seq2ropath(normalize_ps(patch_seq))
        if final_ropath.exists():
            # otherwise final patch was delete
            yield final_ropath

def tarfiles2rop_iter(tarfile_list, restrict_index = ()):
    """Integrate tarfiles of diffs into single ROPath iter

    Then filter out all the diffs in that index which don't start with
    the restrict_index.

    """
    diff_iters = map(difftar2path_iter, tarfile_list)
    if restrict_index:
        # Apply filter before integration
        diff_iters = map(lambda i: filter_path_iter(i, restrict_index),
                         diff_iters)
    return integrate_patch_iters(diff_iters)

def Write_ROPaths(base_path, rop_iter):
    """Write out ropaths in rop_iter starting at base_path

    Returns 1 if something was actually written, 0 otherwise.

    """
    ITR = IterTreeReducer(ROPath_IterWriter, [base_path])
    return_val = 0
    for ropath in rop_iter:
        return_val = 1
        ITR(ropath.index, ropath)
    ITR.Finish()
    base_path.setdata()
    return return_val

class ROPath_IterWriter(ITRBranch):
    """Used in Write_ROPaths above

    We need to use an ITR because we have to update the
    permissions/times of directories after we write the files in them.

    """
    def __init__(self, base_path):
        """Set base_path, Path of root of tree"""
        self.base_path = base_path
        self.dir_diff_ropath = None
        self.dir_new_path = None

    def start_process(self, index, ropath):
        """Write ropath.  Only handles the directory case"""
        if not ropath.isdir():
            # Base may not be a directory, but rest should
            assert ropath.index == (), ropath.index
            new_path = self.base_path.new_index(index)
            if ropath.exists():
                if new_path.exists():
                    new_path.deltree()
                ropath.copy(new_path)

        self.dir_new_path = self.base_path.new_index(index)
        if self.dir_new_path.exists() and not globals.force:
            # base may exist, but nothing else
            assert index == (), index
        else:
            self.dir_new_path.mkdir()
        self.dir_diff_ropath = ropath

    def end_process(self):
        """Update information of a directory when leaving it"""
        if self.dir_diff_ropath:
            self.dir_diff_ropath.copy_attribs(self.dir_new_path)

    def can_fast_process(self, index, ropath):
        """Can fast process (no recursion) if ropath isn't a directory"""
        log.Info(_("Writing %s of type %s") %
                 (ropath.get_relative_path(), ropath.type),
                 log.InfoCode.patch_file_writing,
                 "%s %s" % (util.escape(ropath.get_relative_path()), ropath.type))
        return not ropath.isdir()

    def fast_process(self, index, ropath):
        """Write non-directory ropath to destination"""
        if ropath.exists():
            ropath.copy(self.base_path.new_index(index))


