# -*- 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

import os #@UnusedImport
import re #@UnusedImport
import stat #@UnusedImport
import sys

from duplicity.path import * #@UnusedWildImport
from duplicity import log #@Reimport
from duplicity import globals #@Reimport
from duplicity import diffdir
from duplicity import util #@Reimport

"""Iterate exactly the requested files in a directory

Parses includes and excludes to yield correct files.  More
documentation on what this code does can be found on the man page.

"""

class SelectError(Exception):
    """Some error dealing with the Select class"""
    pass

class FilePrefixError(SelectError):
    """Signals that a specified file doesn't start with correct prefix"""
    pass

class GlobbingError(SelectError):
    """Something has gone wrong when parsing a glob string"""
    pass


class Select:
    """Iterate appropriate Paths in given directory

    This class acts as an iterator on account of its next() method.
    Basically, it just goes through all the files in a directory in
    order (depth-first) and subjects each file to a bunch of tests
    (selection functions) in order.  The first test that includes or
    excludes the file means that the file gets included (iterated) or
    excluded.  The default is include, so with no tests we would just
    iterate all the files in the directory in order.

    The one complication to this is that sometimes we don't know
    whether or not to include a directory until we examine its
    contents.  For instance, if we want to include all the **.py
    files.  If /home/ben/foo.py exists, we should also include /home
    and /home/ben, but if these directories contain no **.py files,
    they shouldn't be included.  For this reason, a test may not
    include or exclude a directory, but merely "scan" it.  If later a
    file in the directory gets included, so does the directory.

    As mentioned above, each test takes the form of a selection
    function.  The selection function takes a path, and returns:

    None - means the test has nothing to say about the related file
    0 - the file is excluded by the test
    1 - the file is included
    2 - the test says the file (must be directory) should be scanned

    Also, a selection function f has a variable f.exclude which should
    be true iff f could potentially exclude some file.  This is used
    to signal an error if the last function only includes, which would
    be redundant and presumably isn't what the user intends.

    """
    # This re should not match normal filenames, but usually just globs
    glob_re = re.compile("(.*[*?[]|ignorecase\\:)", re.I | re.S)

    def __init__(self, path):
        """Initializer, called with Path of root directory"""
        assert isinstance(path, Path), str(path)
        self.selection_functions = []
        self.rootpath = path
        self.prefix = self.rootpath.name

    def set_iter(self):
        """Initialize generator, prepare to iterate."""
        self.rootpath.setdata() # this may have changed since Select init
        self.iter = self.Iterate(self.rootpath)
        self.next = self.iter.next
        self.__iter__ = lambda: self
        return self

    def Iterate(self, path):
        """Return iterator yielding paths in path

        This function looks a bit more complicated than it needs to be
        because it avoids extra recursion (and no extra function calls
        for non-directory files) while still doing the "directory
        scanning" bit.

        """
        def error_handler(exc, path, filename):
            fullpath = os.path.join(path.name, filename)
            try:
                mode = os.stat(fullpath)[stat.ST_MODE]
                if stat.S_ISSOCK(mode):
                    log.Info(_("Skipping socket %s") % fullpath,
                             log.InfoCode.skipping_socket,
                             util.escape(fullpath))
                else:
                    log.Warn(_("Error initializing file %s") % fullpath,
                             log.WarningCode.cannot_iterate,
                             util.escape(fullpath))
            except OSError:
                log.Warn(_("Error accessing possibly locked file %s") % fullpath,
                         log.WarningCode.cannot_stat,
                         util.escape(fullpath))
            return None

        def diryield(path):
            """Generate relevant files in directory path

            Returns (path, num) where num == 0 means path should be
            generated normally, num == 1 means the path is a directory
            and should be included iff something inside is included.

            """
            # todo: get around circular dependency issue by importing here
            from duplicity import robust #@Reimport
            for filename in robust.listpath(path):
                new_path = robust.check_common_error(
                    error_handler, Path.append, (path, filename))
                # make sure file is read accessible
                if (new_path and new_path.type in ["reg", "dir"]
                    and not os.access(new_path.name, os.R_OK)):
                    log.Warn(_("Error accessing possibly locked file %s") % new_path.name,
                             log.WarningCode.cannot_read,
                             util.escape(new_path.name))
                    if diffdir.stats:
                        diffdir.stats.Errors +=1
                    new_path = None
                elif new_path:
                    s = self.Select(new_path)
                    if s == 1:
                        yield (new_path, 0)
                    elif s == 2 and new_path.isdir():
                        yield (new_path, 1)

        if not path.type:
            # base doesn't exist
            log.Warn(_("Warning: base %s doesn't exist, continuing") %
                     path.name)
            return
        log.Debug(_("Selecting %s") % path.name)
        yield path
        if not path.isdir():
            return
        diryield_stack = [diryield(path)]
        delayed_path_stack = []

        while diryield_stack:
            try:
                subpath, val = diryield_stack[-1].next()
            except StopIteration:
                diryield_stack.pop()
                if delayed_path_stack:
                    delayed_path_stack.pop()
                continue
            if val == 0:
                if delayed_path_stack:
                    for delayed_path in delayed_path_stack:
                        log.Log(_("Selecting %s") % delayed_path.name, 6)
                        yield delayed_path
                    del delayed_path_stack[:]
                log.Debug(_("Selecting %s") % subpath.name)
                yield subpath
                if subpath.isdir():
                    diryield_stack.append(diryield(subpath))
            elif val == 1:
                delayed_path_stack.append(subpath)
                diryield_stack.append(diryield(subpath))

    def Select(self, path):
        """Run through the selection functions and return dominant val 0/1/2"""
        if not self.selection_functions:
            return 1
        scan_pending = False
        for sf in self.selection_functions[:-1]:
            result = sf(path)
            if result is 2:
                scan_pending = True
            if result in [0, 1]:
                return result
        if scan_pending:
            return 2
        sf = self.selection_functions[-1]
        result = sf(path)
        if result is not None:
            return result
        else:
            return 1

    def ParseArgs(self, argtuples, filelists):
        """Create selection functions based on list of tuples

        The tuples are created when the initial commandline arguments
        are read.  They have the form (option string, additional
        argument) except for the filelist tuples, which should be
        (option-string, (additional argument, filelist_fp)).

        """
        filelists_index = 0
        try:
            for opt, arg in argtuples:
                if opt == "--exclude":
                    self.add_selection_func(self.glob_get_sf(arg, 0))
                elif opt == "--exclude-if-present":
                    self.add_selection_func(self.present_get_sf(arg, 0))
                elif opt == "--exclude-device-files":
                    self.add_selection_func(self.devfiles_get_sf())
                elif opt == "--exclude-filelist":
                    self.add_selection_func(self.filelist_get_sf(
                        filelists[filelists_index], 0, arg))
                    filelists_index += 1
                elif opt == "--exclude-globbing-filelist":
                    map(self.add_selection_func,
                        self.filelist_globbing_get_sfs(filelists[filelists_index], 0, arg))
                    filelists_index += 1
                elif opt == "--exclude-other-filesystems":
                    self.add_selection_func(self.other_filesystems_get_sf(0))
                elif opt == "--exclude-regexp":
                    self.add_selection_func(self.regexp_get_sf(arg, 0))
                elif opt == "--include":
                    self.add_selection_func(self.glob_get_sf(arg, 1))
                elif opt == "--include-filelist":
                    self.add_selection_func(self.filelist_get_sf(
                        filelists[filelists_index], 1, arg))
                    filelists_index += 1
                elif opt == "--include-globbing-filelist":
                    map(self.add_selection_func,
                        self.filelist_globbing_get_sfs(filelists[filelists_index], 1, arg))
                    filelists_index += 1
                elif opt == "--include-regexp":
                    self.add_selection_func(self.regexp_get_sf(arg, 1))
                else:
                    assert 0, "Bad selection option %s" % opt
        except SelectError, e:
            self.parse_catch_error(e)
        assert filelists_index == len(filelists)
        self.parse_last_excludes()

    def parse_catch_error(self, exc):
        """Deal with selection error exc"""
        if isinstance(exc, FilePrefixError):
            log.FatalError(_(
"""Fatal Error: The file specification
    %s
cannot match any files in the base directory
    %s
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.""") %
            (exc, self.prefix), log.ErrorCode.file_prefix_error)
        elif isinstance(exc, GlobbingError):
            log.FatalError(_("Fatal Error while processing expression\n"
                             "%s") % exc, log.ErrorCode.globbing_error)
        else:
            raise

    def parse_last_excludes(self):
        """Exit with error if last selection function isn't an exclude"""
        if (self.selection_functions and
            not self.selection_functions[-1].exclude):
            log.FatalError(_(
"""Last selection expression:
    %s
only specifies that files be included.  Because the default is to
include all files, the expression is redundant.  Exiting because this
probably isn't what you meant.""") %
            (self.selection_functions[-1].name,),
            log.ErrorCode.redundant_inclusion)

    def add_selection_func(self, sel_func, add_to_start = None):
        """Add another selection function at the end or beginning"""
        if add_to_start:
            self.selection_functions.insert(0, sel_func)
        else:
            self.selection_functions.append(sel_func)

    def filelist_get_sf(self, filelist_fp, inc_default, filelist_name):
        """Return selection function by reading list of files

        The format of the filelist is documented in the man page.
        filelist_fp should be an (open) file object.
        inc_default should be true if this is an include list,
        false for an exclude list.
        filelist_name is just a string used for logging.

        """
        log.Notice(_("Reading filelist %s") % filelist_name)
        tuple_list, something_excluded = \
                    self.filelist_read(filelist_fp, inc_default, filelist_name)
        log.Notice(_("Sorting filelist %s") % filelist_name)
        tuple_list.sort()
        i = [0] # We have to put index in list because of stupid scoping rules

        def selection_function(path):
            while 1:
                if i[0] >= len(tuple_list):
                    return None
                include, move_on = \
                         self.filelist_pair_match(path, tuple_list[i[0]])
                if move_on:
                    i[0] += 1
                    if include is None:
                        continue # later line may match
                return include

        selection_function.exclude = something_excluded or inc_default == 0
        selection_function.name = "Filelist: " + filelist_name
        return selection_function

    def filelist_read(self, filelist_fp, include, filelist_name):
        """Read filelist from fp, return (tuplelist, something_excluded)"""
        prefix_warnings = [0]
        def incr_warnings(exc):
            """Warn if prefix is incorrect"""
            prefix_warnings[0] += 1
            if prefix_warnings[0] < 6:
                log.Warn(_("Warning: file specification '%s' in filelist %s\n"
                           "doesn't start with correct prefix %s.  Ignoring.") %
                         (exc, filelist_name, self.prefix))
                if prefix_warnings[0] == 5:
                    log.Warn(_("Future prefix errors will not be logged."))

        something_excluded, tuple_list = None, []
        separator = globals.null_separator and "\0" or "\n"
        for line in filelist_fp.read().split(separator):
            if not line:
                continue # skip blanks
            try:
                tuple = self.filelist_parse_line(line, include)
            except FilePrefixError, exc:
                incr_warnings(exc)
                continue
            tuple_list.append(tuple)
            if not tuple[1]:
                something_excluded = 1
        if filelist_fp not in (sys.stdin,) and filelist_fp.close():
            log.Warn(_("Error closing filelist %s") % filelist_name)
        return (tuple_list, something_excluded)

    def filelist_parse_line(self, line, include):
        """Parse a single line of a filelist, returning a pair

        pair will be of form (index, include), where index is another
        tuple, and include is 1 if the line specifies that we are
        including a file.  The default is given as an argument.
        prefix is the string that the index is relative to.

        """
        line = line.strip()
        if line[:2] == "+ ":
            # Check for "+ "/"- " syntax
            include = 1
            line = line[2:]
        elif line[:2] == "- ":
            include = 0
            line = line[2:]

        if not line.startswith(self.prefix):
            raise FilePrefixError(line)
        line = line[len(self.prefix):] # Discard prefix
        index = tuple(filter(lambda x: x, line.split("/"))) # remove empties
        return (index, include)

    def filelist_pair_match(self, path, pair):
        """Matches a filelist tuple against a path

        Returns a pair (include, move_on).  include is None if the
        tuple doesn't match either way, and 0/1 if the tuple excludes
        or includes the path.

        move_on is true if the tuple cannot match a later index, and
        so we should move on to the next tuple in the index.

        """
        index, include = pair
        if include == 1:
            if index < path.index:
                return (None, True)
            if index == path.index:
                return (1, True)
            elif index[:len(path.index)] == path.index:
                return (1, False) # /foo/bar implicitly includes /foo
            else:
                return (None, False) # path greater, not initial sequence
        elif include == 0:
            if path.index[:len(index)] == index:
                return (0, False) # /foo implicitly excludes /foo/bar
            elif index < path.index:
                return (None, True)
            else:
                return (None, False) # path greater, not initial sequence
        else:
            assert 0, "Include is %s, should be 0 or 1" % (include,)

    def filelist_globbing_get_sfs(self, filelist_fp, inc_default, list_name):
        """Return list of selection functions by reading fileobj

        filelist_fp should be an open file object
        inc_default is true iff this is an include list
        list_name is just the name of the list, used for logging
        See the man page on --[include/exclude]-globbing-filelist

        """
        log.Notice(_("Reading globbing filelist %s") % list_name)
        separator = globals.null_separator and "\0" or "\n"
        for line in filelist_fp.read().split(separator):
            if not line: # skip blanks
                continue
            if line[0] == "#": # skip comments
                continue
            if line[:2] == "+ ":
                yield self.glob_get_sf(line[2:], 1)
            elif line[:2] == "- ":
                yield self.glob_get_sf(line[2:], 0)
            else:
                yield self.glob_get_sf(line, inc_default)

    def other_filesystems_get_sf(self, include):
        """Return selection function matching files on other filesystems"""
        assert include == 0 or include == 1
        root_devloc = self.rootpath.getdevloc()
        def sel_func(path):
            if path.exists() and path.getdevloc() != root_devloc:
                return include
            else:
                return None
        sel_func.exclude = not include
        sel_func.name = "Match other filesystems"
        return sel_func

    def regexp_get_sf(self, regexp_string, include):
        """Return selection function given by regexp_string"""
        assert include == 0 or include == 1
        try:
            regexp = re.compile(regexp_string)
        except Exception:
            log.Warn(_("Error compiling regular expression %s") % regexp_string)
            raise

        def sel_func(path):
            if regexp.search(path.name):
                return include
            else:
                return None

        sel_func.exclude = not include
        sel_func.name = "Regular expression: %s" % regexp_string
        return sel_func

    def devfiles_get_sf(self):
        """Return a selection function to exclude all dev files"""
        if self.selection_functions:
            log.Warn(_("Warning: exclude-device-files is not the first "
                       "selector.\nThis may not be what you intended"))
        def sel_func(path):
            if path.isdev():
                return 0
            else:
                return None
        sel_func.exclude = 1
        sel_func.name = "Exclude device files"
        return sel_func

    def glob_get_sf(self, glob_str, include):
        """Return selection function given by glob string"""
        assert include == 0 or include == 1
        if glob_str == "**":
            sel_func = lambda path: include
        elif not self.glob_re.match(glob_str):
            # normal file
            sel_func = self.glob_get_filename_sf(glob_str, include)
        else:
            sel_func = self.glob_get_normal_sf(glob_str, include)

        sel_func.exclude = not include
        sel_func.name = "Command-line %s glob: %s" % \
                        (include and "include" or "exclude", glob_str)
        return sel_func

    def present_get_sf(self, filename, include):
        """Return selection function given by existence of a file in a directory"""
        assert include == 0 or include == 1

        def exclude_sel_func(path):
            # do not follow symbolic links when checking for file existence!
            # path.append creates a new path object, which in turn uses setdata
            # which in turn follows symbolic links...
            if path.issym():
                return None
            if path.append(filename).exists():
                return 0
            else:
                return None

        if include == 0:
            sel_func = exclude_sel_func
        else:
            log.FatalError("--include-if-present not implemented (would it make sense?).",
                           log.ErrorCode.not_implemented)

        sel_func.exclude = not include
        sel_func.name = "Command-line %s filename: %s" % \
                        (include and "include-if-present" or "exclude-if-present", filename)
        return sel_func

    def glob_get_filename_sf(self, filename, include):
        """Get a selection function given a normal filename

        Some of the parsing is better explained in
        filelist_parse_line.  The reason this is split from normal
        globbing is things are a lot less complicated if no special
        globbing characters are used.

        """
        if not filename.startswith(self.prefix):
            raise FilePrefixError(filename)
        index = tuple(filter(lambda x: x,
                             filename[len(self.prefix):].split("/")))
        return self.glob_get_tuple_sf(index, include)

    def glob_get_tuple_sf(self, tuple, include):
        """Return selection function based on tuple"""
        def include_sel_func(path):
            if (path.index == tuple[:len(path.index)] or
                path.index[:len(tuple)] == tuple):
                return 1 # /foo/bar implicitly matches /foo, vice-versa
            else:
                return None

        def exclude_sel_func(path):
            if path.index[:len(tuple)] == tuple:
                return 0 # /foo excludes /foo/bar, not vice-versa
            else:
                return None

        if include == 1:
            sel_func = include_sel_func
        elif include == 0:
            sel_func = exclude_sel_func
        sel_func.exclude = not include
        sel_func.name = "Tuple select %s" % (tuple,)
        return sel_func

    def glob_get_normal_sf(self, glob_str, include):
        """Return selection function based on glob_str

        The basic idea is to turn glob_str into a regular expression,
        and just use the normal regular expression.  There is a
        complication because the selection function should return '2'
        (scan) for directories which may contain a file which matches
        the glob_str.  So we break up the glob string into parts, and
        any file which matches an initial sequence of glob parts gets
        scanned.

        Thanks to Donovan Baarda who provided some code which did some
        things similar to this.

        """
        if glob_str.lower().startswith("ignorecase:"):
            re_comp = lambda r: re.compile(r, re.I | re.S)
            glob_str = glob_str[len("ignorecase:"):]
        else:
            re_comp = lambda r: re.compile(r, re.S)

        # matches what glob matches and any files in directory
        glob_comp_re = re_comp("^%s($|/)" % self.glob_to_re(glob_str))

        if glob_str.find("**") != -1:
            glob_str = glob_str[:glob_str.find("**")+2] # truncate after **

        scan_comp_re = re_comp("^(%s)$" %
                               "|".join(self.glob_get_prefix_res(glob_str)))

        def include_sel_func(path):
            if glob_comp_re.match(path.name):
                return 1
            elif scan_comp_re.match(path.name):
                return 2
            else:
                return None

        def exclude_sel_func(path):
            if glob_comp_re.match(path.name):
                return 0
            else:
                return None

        # Check to make sure prefix is ok
        if not include_sel_func(self.rootpath):
            raise FilePrefixError(glob_str)

        if include:
            return include_sel_func
        else:
            return exclude_sel_func

    def glob_get_prefix_res(self, glob_str):
        """Return list of regexps equivalent to prefixes of glob_str"""
        glob_parts = glob_str.split("/")
        if "" in glob_parts[1:-1]:
            # "" OK if comes first or last, as in /foo/
            raise GlobbingError("Consecutive '/'s found in globbing string "
                                + glob_str)

        prefixes = map(lambda i: "/".join(glob_parts[:i+1]),
                       range(len(glob_parts)))
        # we must make exception for root "/", only dir to end in slash
        if prefixes[0] == "":
            prefixes[0] = "/"
        return map(self.glob_to_re, prefixes)

    def glob_to_re(self, pat):
        """Returned regular expression equivalent to shell glob pat

        Currently only the ?, *, [], and ** expressions are supported.
        Ranges like [a-z] are also currently unsupported.  There is no
        way to quote these special characters.

        This function taken with minor modifications from efnmatch.py
        by Donovan Baarda.

        """
        i, n, res = 0, len(pat), ''
        while i < n:
            c, s = pat[i], pat[i:i+2]
            i = i+1
            if s == '**':
                res = res + '.*'
                i = i + 1
            elif c == '*':
                res = res + '[^/]*'
            elif c == '?':
                res = res + '[^/]'
            elif c == '[':
                j = i
                if j < n and pat[j] in '!^':
                    j = j+1
                if j < n and pat[j] == ']':
                    j = j+1
                while j < n and pat[j] != ']':
                    j = j+1
                if j >= n:
                    res = res + '\\[' # interpret the [ literally
                else:
                    # Deal with inside of [..]
                    stuff = pat[i:j].replace('\\','\\\\')
                    i = j+1
                    if stuff[0] in '!^':
                        stuff = '^' + stuff[1:]
                    res = res + '[' + stuff + ']'
            else:
                res = res + re.escape(c)
        return res

