# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4; encoding:utf-8 -*-
#
# Copyright 2002 Ben Escoto
# Copyright 2007 Kenneth Loafman
#
# 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


import tempfile

from duplicity import diffdir
from duplicity import dup_tarfile
from duplicity import errors
from duplicity import selection
from duplicity import tempdir
from duplicity.path import *  # pylint: disable=unused-wildcard-import,redefined-builtin

"""Functions for patching of directories"""


class PatchDirException(Exception):
    pass


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 must be a non-empty tuple specifying the path prefix"
    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.
    try:
        tarinfo_list = [next(tar_iter)]
    except StopIteration:
        return

    while True:
        # This section relevant when a multivol diff is last in tar
        if not tarinfo_list[0]:
            return
        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
        try:
            tarinfo_list[0] = next(tar_iter)
        except StopIteration:
            return


def get_index_from_tarinfo(tarinfo):
    """Return (index, difftype, multivol) pair from tarinfo object"""
    for prefix in [
        "snapshot/",
        "diff/",
        "deleted/",
        "multivol_diff/",
        "multivol_snapshot/",
    ]:
        tiname = util.get_tarinfo_name(tarinfo)
        if tiname.startswith(prefix):
            name = tiname[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", tiname)
                if num_subs != 1:
                    raise PatchDirException(f"Unrecognized diff entry {tiname}")
            else:
                difftype = prefix[:-1]  # strip trailing /
                name = tiname[len(prefix) :]
                if name.endswith(r"/"):
                    name = name[:-1]  # strip trailing /'s
                multivol = 0
            break
    else:
        raise PatchDirException(f"Unrecognized diff entry {tiname}")
    if name == r"." or name == r"":
        index = ()
    else:
        index = tuple(os.fsencode(name).split(b"/"))
        if b".." in index:
            raise PatchDirException(f"Tar entry {os.fsdecode(tiname)} contains '..'.  Security violation")
    return index, difftype, multivol


class Multivol_Filelike(object):
    """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 = b""
        self.at_end = False

    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 False
        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 = True
            return False

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

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

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


class TarFile_FromFileobjs(object):
    """Like a dup_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.dup_tarfile, self.tar_iter = None, None
        self.current_fp = None

    def __iter__(self):  # pylint: disable=non-iterator-returned
        return self

    def set_tarfile(self):
        """Set dup_tarfile from next file object, or raise StopIteration"""
        if self.current_fp:
            assert (
                not self.current_fp.close()
            ), "Closing current file pointer returned a truthy value indicating an error"

        self.current_fp = next(self.fileobj_iter)

        self.dup_tarfile = util.make_tarfile("r", self.current_fp)
        self.tar_iter = iter(self.dup_tarfile)

    def __next__(self):
        if not self.dup_tarfile:
            try:
                self.set_tarfile()
            except StopIteration:
                return
        try:
            return next(self.tar_iter)
        except StopIteration:
            assert not self.dup_tarfile.close(), "self.dup_tarfile failed to close"
            self.set_tarfile()
            return next(self.tar_iter)

    def extractfile(self, tarinfo):
        """Return data associated with given tarinfo"""
        return self.dup_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] = next(iter_list[i])
                except StopIteration:
                    overflow[i] = 1
                    elems[i] = None

    def getleastindex(elems):
        """Return the first index in elems, assuming elems isn't empty"""
        return min([elem.index for elem in [x for x in elems if x]])

    def yield_tuples(iter_num, overflow, elems):
        while True:
            setrorps(overflow, elems)
            if None not 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)


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", f"First patch in sequence {patch_seq} was a diff"
    if not first.isreg():
        # No need to bother with data if not regular file
        assert len(patch_seq) == 1, f"Patch sequence isn't regular, but has {len(patch_seq)} entries"
        return first.get_ropath()

    current_file = first.open("rb")

    for delta_ropath in patch_seq[1:]:
        assert (
            delta_ropath.difftype == "diff"
        ), f"Expected difftype 'diff' in patch sequence, got {delta_ropath.difftype}"
        try:
            cur_file.fileno()
        except Exception as e:
            """
            librsync insists on a real file object, which we create manually
            by using the duplicity.tempdir to tell us where.

            See https://bugs.launchpad.net/duplicity/+bug/670891 for discussion
            of os.tmpfile() vs tempfile.TemporaryFile() w.r.t. Windows / Posix,
            which is worked around in librsync.PatchedFile() now.
            """
            tempfp = tempfile.TemporaryFile(dir=tempdir.default().dir())
            util.copyfileobj(current_file, tempfp)
            assert (
                not current_file.close()
            ), "Closing temporary current_file returned a truthy value indicating an error"
            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:
        normalized = normalize_ps(patch_seq)
        try:
            final_ropath = patch_seq2ropath(normalized)
            if final_ropath.exists():
                # otherwise final patch was delete
                yield final_ropath
        except Exception as e:
            filename = normalized[-1].get_ropath().get_relative_path()
            log.Warn(
                _("Error '%s' patching %s") % (util.uexc(e), os.fsdecode(filename)),
                log.WarningCode.cannot_process,
                util.escape(filename),
            )


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 = [difftar2path_iter(x) for x in tarfile_list]
    if restrict_index:
        # Apply filter before integration
        diff_iters = [filter_path_iter(x, restrict_index) for x in 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 == (), f"{ropath.index} not empty"
            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 config.force:
            # base may exist, but nothing else
            assert index == (), f"{index} not empty"
        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):  # pylint: disable=unused-argument
        """Can fast process (no recursion) if ropath isn't a directory"""
        log.Info(
            _("Writing %s of type %s") % (os.fsdecode(ropath.get_relative_path()), ropath.type),
            log.InfoCode.patch_file_writing,
            f"{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))
