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# Copyright (C) 2015 Chintalagiri Shashank 

# 

# This file is part of Tendril. 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU Affero General Public License as published by 

# the Free Software Foundation, either version 3 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 Affero General Public License for more details. 

# 

# You should have received a copy of the GNU Affero General Public License 

# along with this program.  If not, see <http://www.gnu.org/licenses/>. 

""" 

The Filesystem Utils Module (:mod:`tendril.utils.fsutils`) 

========================================================== 

 

This module provides utilities to deal with filesystems. For the most part, 

this module basically proxies specific requests to various other third-party 

or python libraries. 

 

.. rubric:: Module Contents 

 

.. autosummary:: 

 

    TEMPDIR 

    get_tempname 

    fsutils_cleanup 

    zipdir 

 

    Crumb 

    get_path_breadcrumbs 

 

    get_folder_mtime 

    get_file_mtime 

    get_file_hash 

    VersionedOutputFile 

 

    import_ 

 

""" 

 

import imp 

import tempfile 

import zipfile 

import atexit 

import os 

import glob 

import string 

import hashlib 

import base64 

 

from fs.opener import fsopendir 

from fs.errors import ResourceNotFoundError 

 

from datetime import datetime 

from collections import namedtuple 

 

from tendril.utils import log 

logger = log.get_logger(__name__, log.INFO) 

 

 

if tempfile.tempdir is None: 

    tempfile.tempdir = tempfile.mkdtemp() 

 

 

#: The path to the temporary directory which all application code can import, 

#: and create whatever temporary files it needs within it. 

#: 

#: This directory will be removed by Tendril at clean application exit or 

#: by the Operating System as per it's policies. 

#: 

#: Every execution of tendril in a separate process owns it's own temporary 

#: directory. 

#: 

#: .. seealso:: :func:`fsutils_cleanup` 

#: 

TEMPDIR = tempfile.gettempdir() 

temp_fs = fsopendir(TEMPDIR) 

 

 

def get_tempname(): 

    """ 

    Gets a random string for use as a temporary filename. 

 

    :return: A filename that can be used. 

    """ 

    return next(tempfile._get_candidate_names()) 

 

 

def zipdir(path, zfpath): 

    """ 

    Creates a zip file at ``zfpath`` containing all the files in ``path``. 

    This function is simple wrapper around python's :mod:`zipfile` module. 

 

    :param path: Path of the source folder, which is to be added to the zip 

                 file. 

    :param zfpath: Path of the zip file to create. 

    :return: The path of the created zip file. 

 

    """ 

    zfile = zipfile.ZipFile(zfpath, 'w') 

    for root, dirs, files in os.walk(path): 

        for f in files: 

            zfile.write( 

                os.path.join(root, f), 

                os.path.relpath( 

                    os.path.join(root, f), os.path.join(path, '..') 

                ) 

            ) 

    zfile.close() 

    return zfpath 

 

 

#: A named tuple definition for a Crumb of a Breadcrumb. 

#: This can be used to construct breadcrumb navigation by application 

#: code. While it resides in the :mod:`tendril.utils.fs` module, the same 

#: type should be used for other forms of breadcrumbs as well. It is 

#: placed here due to its proximity to :mod:`os.path`. 

Crumb = namedtuple('Crumb', 'name path') 

 

 

def get_path_breadcrumbs(path, base=None, rootst='Root'): 

    """ 

    Given a certain filesystem ``path`` and an optional ``base``, this 

    function returns a list of :class:`Crumb` objects, forming the breadcrumbs 

    to that path from the base. The value of ``rootst`` is prepended to the 

    list, providing a means to insert a title indicating the base of the 

    breadcrumb list. 

 

    :param path: The path to the target, compatible with :mod:`os.path` 

    :type path: str 

    :param base: The path of the base, compatible with :mod:`os.path`. 

                 Optional. 

    :type base: str 

    :param rootst: The string for the root breadcrumb. 

    :type rootst: str 

    :return: The breadcrumbs. 

    :rtype: :class:`list` of :class:`Crumb` 

 

    """ 

    if base is not None: 

        path = os.path.relpath(path, base) 

    crumbs = [] 

    while True: 

        head, tail = os.path.split(path) 

        if not tail: 

            break 

        crumbs = [Crumb(name=tail, path=path)] + crumbs 

        path = head 

    crumbs = [Crumb(name=rootst, path='')] + crumbs 

    return crumbs 

 

 

def get_folder_mtime(folder, fs=None): 

    """ 

    Given the path to a certain filesystem ``folder``, this function returns 

    a :class:`datetime.datetime` instance representing the time of the latest 

    change of any file contained within the folder. 

 

    :param folder: The path to the ``folder``, compatible with :mod:`os.path` 

    :type folder: str 

    :param fs: The pyfilesystem to use. (Default) None for local fs. 

    :type fs: :class:`fs.base.FS` 

    :return: The time of the latest change within the ``folder`` 

    :rtype: :class:`datetime.datetime` 

 

    .. seealso:: :func:`get_file_mtime` 

 

    """ 

    last_change = None 

    if fs is None: 

        filelist = [os.path.join(folder, f) for f in os.listdir(folder)] 

        for f in filelist: 

            if os.path.isfile(f): 

                fct = get_file_mtime(f) 

            elif os.path.isdir(f): 

                fct = get_folder_mtime(f) 

            else: 

                raise OSError("Not file, not directory : " + f) 

            if fct is not None and (last_change is None or fct > last_change): 

                last_change = fct 

    else: 

        filelist = fs.listdir(path=folder, files_only=True, full=True) 

        dirlist = fs.listdir(path=folder, dirs_only=True, full=True) 

        for f in filelist: 

            fct = get_file_mtime(f, fs) 

            if last_change is None or fct > last_change: 

                last_change = fct 

        for d in dirlist: 

            fct = get_folder_mtime(d, fs) 

            if last_change is None or fct > last_change: 

                last_change = fct 

    return last_change 

 

 

def get_file_mtime(f, fs=None): 

    """ 

    Given the path to a certain filesystem ``file``, this function returns 

    a :class:`datetime.datetime` instance representing the time of the latest 

    change of that file. 

 

    :param f: The path to the ``file``, compatible with :mod:`os.path` 

    :type f: str 

    :param fs: The pyfilesystem to use. (Default) None for local fs. 

    :type fs: :class:`fs.base.FS` 

    :return: The time of the latest change within the ``folder`` 

    :rtype: :class:`datetime.datetime` 

 

    .. seealso:: :func:`get_folder_mtime` 

 

    """ 

    if fs is None: 

        try: 

            return datetime.fromtimestamp(os.path.getmtime(f)) 

        except OSError: 

            return None 

    else: 

        try: 

            return fs.getinfo(f)['modified_time'] 

        except ResourceNotFoundError: 

            return None 

 

 

def get_file_hash(filepath, hasher=None, blocksize=65536): 

    """ 

    Return the hash of the file located at the given filepath, using 

    the hasher specified. The hash is encoded in base64 to make it 

    shorter while preserving collision resistance. Note that the 

    resulting hash is case sensitive. 

 

    .. seealso:: :mod:`hashlib` 

 

    :param filepath: Path of the file which needs to be hashed. 

    :param hasher: Hash function to use. Default :mod:`hashlib.sha256` 

    :param blocksize: Size of each block to hash. 

    :return: The hex digest for the file. 

    """ 

    if hasher is None: 

        hasher = hashlib.sha256() 

    with open(filepath, 'rb') as afile: 

        buf = afile.read(blocksize) 

        while len(buf) > 0: 

            hasher.update(buf) 

            buf = afile.read(blocksize) 

    return base64.b64encode(hasher.digest()) 

 

 

class VersionedOutputFile: 

    """ 

    This is like a file object opened for output, but it makes 

    versioned backups of anything it might otherwise overwrite. 

 

    `http://code.activestate.com/recipes/\ 

52277-saving-backups-when-writing-files/`_ 

    """ 

 

    def __init__(self, pathname, numSavedVersions=3): 

        """ 

        Create a new output file. 

 

        :param pathname: The name of the file to [over]write. 

        :param numSavedVersions: How many of the most recent versions of 

                                 `pathname` to save. 

 

        """ 

 

        self._pathname = pathname 

        self._tmpPathname = "%s.~new~" % self._pathname 

        self._numSavedVersions = numSavedVersions 

        self._outf = open(self._tmpPathname, "wb") 

 

    def __del__(self): 

        self.close() 

 

    def close(self): 

        if self._outf: 

            self._outf.close() 

            self._replace_current_file() 

            self._outf = None 

 

    def as_file(self): 

        """ 

        Return self's shadowed file object, since marshal is 

        pretty insistent on working w. pure file objects. 

        """ 

        return self._outf 

 

    def __getattr__(self, attr): 

        """ 

        Delegate most operations to self's open file object. 

        """ 

        return getattr(self.__dict__['_outf'], attr) 

 

    def _replace_current_file(self): 

        """ 

        Replace the current contents of self's named file. 

        """ 

        self._backup_current_file() 

        os.rename(self._tmpPathname, self._pathname) 

 

    def _backup_current_file(self): 

        """ 

        Save a numbered backup of self's named file. 

        """ 

        # If the file doesn't already exist, there's nothing to do. 

        if os.path.isfile(self._pathname): 

            new_name = self._versioned_name(self._current_revision() + 1) 

            os.rename(self._pathname, new_name) 

 

            # Maybe get rid of old versions. 

            if (self._numSavedVersions is not None) and \ 

                    (self._numSavedVersions > 0): 

                self._delete_old_revisions() 

 

    def _versioned_name(self, revision): 

        """ 

        Get self's pathname with a revision number appended. 

        """ 

        return "%s.~%s~" % (self._pathname, revision) 

 

    def _current_revision(self): 

        """ 

        Get the revision number of self's largest existing backup. 

        """ 

        revisions = [0] + self._revisions() 

        return max(revisions) 

 

    def _revisions(self): 

        """ 

        Get the revision numbers of all of self's backups. 

        """ 

        revisions = [] 

        backup_names = glob.glob("%s.~[0-9]*~" % self._pathname) 

        for name in backup_names: 

            try: 

                revision = int(string.split(name, "~")[-2]) 

                revisions.append(revision) 

            except ValueError: 

                # Some ~[0-9]*~ extensions may not be wholly numeric. 

                pass 

        revisions.sort() 

        return revisions 

 

    def _delete_old_revisions(self): 

        """ 

        Delete old versions of self's file, so that at most 

        :attr:`_numSavedVersions` versions are retained. 

        """ 

        revisions = self._revisions() 

        revisions_to_delete = revisions[:-self._numSavedVersions] 

        for revision in revisions_to_delete: 

            pathname = self._versioned_name(revision) 

            if os.path.isfile(pathname): 

                os.remove(pathname) 

 

 

def fsutils_cleanup(): 

    """ 

    Called when the python interpreter is shutting down. Cleans up all 

    `tendril.utils.fs` related objects and other artifacts created by the 

    module. Each user of the TEMPDIR should clean up it's own files and 

    folders before now. If TEMPDIR is non-empty at this point, this 

    function won't delete the folder. 

 

    Performs the following tasks: 

        - Removes the :data:`TEMPDIR` 

 

    """ 

    try: 

        os.rmdir(tempfile.gettempdir()) 

    except OSError: 

        pass 

 

 

def import_(fpath): 

    """ 

    Imports the file specified by the ``fpath`` parameter using the 

    :mod:`imp` python module and returns the loaded module. 

 

    :param fpath: Path of the python module to import. 

    :return: Module object of the imported python module. 

    """ 

    (path, name) = os.path.split(fpath) 

    (name, ext) = os.path.splitext(name) 

    (f, filename, data) = imp.find_module(name, [path]) 

    return imp.load_module(name, f, filename, data) 

 

 

def get_parent(obj, n=1): 

    """ 

    This function is intended for use by modules imported from outside 

    the package via the filesystem to get around the behavior of python's 

    super() which breaks when something is effectively reloaded. 

 

    .. todo:: A cleaner solution to handle this condition is needed. 

 

    """ 

    import inspect 

    return inspect.getmro(obj.__class__)[n] 

 

 

atexit.register(fsutils_cleanup)