# -*- coding: utf-8 -*-

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# We don't import all modules at the top for performance reasons. See Bug 1008943

from __future__ import absolute_import, print_function

import errno
import os
import stat
import sys
import time
import warnings
from contextlib import contextmanager

from six.moves import urllib


__all__ = ['extract_tarball',
           'extract_zip',
           'extract',
           'is_url',
           'load',
           'move',
           'remove',
           'rmtree',
           'tree',
           'which',
           'NamedTemporaryFile',
           'TemporaryDirectory']

# utilities for extracting archives


def extract_tarball(src, dest):
    """extract a .tar file"""

    import tarfile

    with tarfile.open(src) as bundle:
        namelist = []

        for m in bundle:
            bundle.extract(m, path=dest)
            namelist.append(m.name)

    return namelist


def extract_zip(src, dest):
    """extract a zip file"""

    import zipfile

    if isinstance(src, zipfile.ZipFile):
        bundle = src
    else:
        try:
            bundle = zipfile.ZipFile(src)
        except Exception:
            print("src: %s" % src)
            raise

    namelist = bundle.namelist()

    for name in namelist:
        bundle.extract(name, dest)
        filename = os.path.realpath(os.path.join(dest, name))
        mode = bundle.getinfo(name).external_attr >> 16 & 0x1FF
        # Only update permissions if attributes are set. Otherwise fallback to the defaults.
        if mode:
            os.chmod(filename, mode)
    bundle.close()
    return namelist


def extract(src, dest=None):
    """
    Takes in a tar or zip file and extracts it to dest

    If dest is not specified, extracts to os.path.dirname(src)

    Returns the list of top level files that were extracted
    """

    import zipfile
    import tarfile

    assert os.path.exists(src), "'%s' does not exist" % src

    if dest is None:
        dest = os.path.dirname(src)
    elif not os.path.isdir(dest):
        os.makedirs(dest)
    assert not os.path.isfile(dest), "dest cannot be a file"

    if tarfile.is_tarfile(src):
        namelist = extract_tarball(src, dest)
    elif zipfile.is_zipfile(src):
        namelist = extract_zip(src, dest)
    else:
        raise Exception("mozfile.extract: no archive format found for '%s'" %
                        src)

    # namelist returns paths with forward slashes even in windows
    top_level_files = [os.path.join(dest, name.rstrip('/')) for name in namelist
                       if len(name.rstrip('/').split('/')) == 1]

    # namelist doesn't include folders, append these to the list
    for name in namelist:
        index = name.find('/')
        if index != -1:
            root = os.path.join(dest, name[:index])
            if root not in top_level_files:
                top_level_files.append(root)

    return top_level_files


# utilities for removal of files and directories

def rmtree(dir):
    """Deprecated wrapper method to remove a directory tree.

    Ensure to update your code to use mozfile.remove() directly

    :param dir: directory to be removed
    """

    warnings.warn("mozfile.rmtree() is deprecated in favor of mozfile.remove()",
                  PendingDeprecationWarning, stacklevel=2)
    return remove(dir)


def _call_windows_retry(func, args=(), retry_max=5, retry_delay=0.5):
    """
    It's possible to see spurious errors on Windows due to various things
    keeping a handle to the directory open (explorer, virus scanners, etc)
    So we try a few times if it fails with a known error.
    retry_delay is multiplied by the number of failed attempts to increase
    the likelihood of success in subsequent attempts.
    """
    retry_count = 0
    while True:
        try:
            func(*args)
        except OSError as e:
            # Error codes are defined in:
            # http://docs.python.org/2/library/errno.html#module-errno
            if e.errno not in (errno.EACCES, errno.ENOTEMPTY):
                raise

            if retry_count == retry_max:
                raise

            retry_count += 1

            print('%s() failed for "%s". Reason: %s (%s). Retrying...' %
                  (func.__name__, args, e.strerror, e.errno))
            time.sleep(retry_count * retry_delay)
        else:
            # If no exception has been thrown it should be done
            break


def remove(path):
    """Removes the specified file, link, or directory tree.

    This is a replacement for shutil.rmtree that works better under
    windows. It does the following things:

     - check path access for the current user before trying to remove
     - retry operations on some known errors due to various things keeping
       a handle on file paths - like explorer, virus scanners, etc. The
       known errors are errno.EACCES and errno.ENOTEMPTY, and it will
       retry up to 5 five times with a delay of (failed_attempts * 0.5) seconds
       between each attempt.

    Note that no error will be raised if the given path does not exists.

    :param path: path to be removed
    """

    import shutil

    def _call_with_windows_retry(*args, **kwargs):
        try:
            _call_windows_retry(*args, **kwargs)
        except OSError as e:
            # The file or directory to be removed doesn't exist anymore
            if e.errno != errno.ENOENT:
                raise

    def _update_permissions(path):
        """Sets specified pemissions depending on filetype"""
        if os.path.islink(path):
            # Path is a symlink which we don't have to modify
            # because it should already have all the needed permissions
            return

        stats = os.stat(path)

        if os.path.isfile(path):
            mode = stats.st_mode | stat.S_IWUSR
        elif os.path.isdir(path):
            mode = stats.st_mode | stat.S_IWUSR | stat.S_IXUSR
        else:
            # Not supported type
            return

        _call_with_windows_retry(os.chmod, (path, mode))

    if not os.path.exists(path):
        return

    if os.path.isfile(path) or os.path.islink(path):
        # Verify the file or link is read/write for the current user
        _update_permissions(path)
        _call_with_windows_retry(os.remove, (path,))

    elif os.path.isdir(path):
        # Verify the directory is read/write/execute for the current user
        _update_permissions(path)

        # We're ensuring that every nested item has writable permission.
        for root, dirs, files in os.walk(path):
            for entry in dirs + files:
                _update_permissions(os.path.join(root, entry))
        _call_with_windows_retry(shutil.rmtree, (path,))


def move(src, dst):
    """
    Move a file or directory path.

    This is a replacement for shutil.move that works better under windows,
    retrying operations on some known errors due to various things keeping
    a handle on file paths.
    """
    import shutil
    _call_windows_retry(shutil.move, (src, dst))


def depth(directory):
    """returns the integer depth of a directory or path relative to '/' """

    directory = os.path.abspath(directory)
    level = 0
    while True:
        directory, remainder = os.path.split(directory)
        level += 1
        if not remainder:
            break
    return level


def tree(directory, sort_key=lambda x: x.lower()):
    """Display tree directory structure for `directory`."""
    vertical_line = u'│'
    item_marker = u'├'
    last_child = u'└'

    retval = []
    indent = []
    last = {}
    top = depth(directory)

    for dirpath, dirnames, filenames in os.walk(directory, topdown=True):

        abspath = os.path.abspath(dirpath)
        basename = os.path.basename(abspath)
        parent = os.path.dirname(abspath)
        level = depth(abspath) - top

        # sort articles of interest
        for resource in (dirnames, filenames):
            resource[:] = sorted(resource, key=sort_key)

        if level > len(indent):
            indent.append(vertical_line)
        indent = indent[:level]

        if dirnames:
            files_end = item_marker
            last[abspath] = dirnames[-1]
        else:
            files_end = last_child

        if last.get(parent) == os.path.basename(abspath):
            # last directory of parent
            dirpath_mark = last_child
            indent[-1] = ' '
        elif not indent:
            dirpath_mark = ''
        else:
            dirpath_mark = item_marker

        # append the directory and piece of tree structure
        # if the top-level entry directory, print as passed
        retval.append('%s%s%s' % (''.join(indent[:-1]),
                                  dirpath_mark,
                                  basename if retval else directory))
        # add the files
        if filenames:
            last_file = filenames[-1]
            retval.extend([('%s%s%s' % (''.join(indent),
                                        files_end if filename == last_file else item_marker,
                                        filename))
                           for index, filename in enumerate(filenames)])

    return '\n'.join(retval)


def which(cmd, mode=os.F_OK | os.X_OK, path=None, exts=None):
    """A wrapper around `shutil.which` to make the behavior on Windows
    consistent with other platforms.

    On non-Windows platforms, this is a direct call to `shutil.which`. On
    Windows, this:

    * Ensures that `cmd` without an extension will be found. Previously it was
      only found if it had an extension in `PATHEXT`.
    * Ensures the absolute path to the binary is returned. Previously if the
      binary was found in `cwd`, a relative path was returned.
    * Checks the Windows registry if shutil.which doesn't come up with anything.

    The arguments are the same as the ones in `shutil.which`. In addition there
    is an `exts` argument that only has an effect on Windows. This is used to
    set a custom value for PATHEXT and is formatted as a list of file
    extensions.
    """
    try:
        from shutil import which as shutil_which
    except ImportError:
        from shutil_which import which as shutil_which

    if isinstance(path, (list, tuple)):
        path = os.pathsep.join(path)

    if sys.platform != "win32":
        return shutil_which(cmd, mode=mode, path=path)

    oldexts = os.environ.get("PATHEXT", "")
    if not exts:
        exts = oldexts.split(os.pathsep)

    # This ensures that `cmd` without any extensions will be found.
    # See: https://bugs.python.org/issue31405
    if "." not in exts:
        exts.append(".")

    os.environ["PATHEXT"] = os.pathsep.join(exts)
    try:
        path = shutil_which(cmd, mode=mode, path=path)
        if path:
            return os.path.abspath(path.rstrip('.'))
    finally:
        if oldexts:
            os.environ["PATHEXT"] = oldexts
        else:
            del os.environ["PATHEXT"]

    # If we've gotten this far, we need to check for registered executables
    # before giving up.
    try:
        import winreg
    except ImportError:
        import _winreg as winreg
    if not cmd.lower().endswith('.exe'):
        cmd += '.exe'
    try:
        ret = winreg.QueryValue(
            winreg.HKEY_LOCAL_MACHINE,
            r'SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\%s' % cmd)
        return os.path.abspath(ret) if ret else None
    except winreg.error:
        return None


# utilities for temporary resources

class NamedTemporaryFile(object):
    """
    Like tempfile.NamedTemporaryFile except it works on Windows
    in the case where you open the created file a second time.

    This behaves very similarly to tempfile.NamedTemporaryFile but may
    not behave exactly the same. For example, this function does not
    prevent fd inheritance by children.

    Example usage:

    with NamedTemporaryFile() as fh:
        fh.write(b'foobar')

        print('Filename: %s' % fh.name)

    see https://bugzilla.mozilla.org/show_bug.cgi?id=821362
    """

    def __init__(self, mode='w+b', bufsize=-1, suffix='', prefix='tmp',
                 dir=None, delete=True):

        import tempfile
        fd, path = tempfile.mkstemp(suffix, prefix, dir, 't' in mode)
        os.close(fd)

        self.file = open(path, mode)
        self._path = path
        self._delete = delete
        self._unlinked = False

    def __getattr__(self, k):
        return getattr(self.__dict__['file'], k)

    def __iter__(self):
        return self.__dict__['file']

    def __enter__(self):
        self.file.__enter__()
        return self

    def __exit__(self, exc, value, tb):
        self.file.__exit__(exc, value, tb)
        if self.__dict__['_delete']:
            os.unlink(self.__dict__['_path'])
            self._unlinked = True

    def __del__(self):
        if self.__dict__['_unlinked']:
            return
        self.file.__exit__(None, None, None)
        if self.__dict__['_delete']:
            os.unlink(self.__dict__['_path'])


@contextmanager
def TemporaryDirectory():
    """
    create a temporary directory using tempfile.mkdtemp, and then clean it up.

    Example usage:
    with TemporaryDirectory() as tmp:
       open(os.path.join(tmp, "a_temp_file"), "w").write("data")

    """

    import tempfile
    import shutil

    tempdir = tempfile.mkdtemp()
    try:
        yield tempdir
    finally:
        shutil.rmtree(tempdir)


# utilities dealing with URLs

def is_url(thing):
    """
    Return True if thing looks like a URL.
    """

    parsed = urllib.parse.urlparse(thing)
    if 'scheme' in parsed:
        return len(parsed.scheme) >= 2
    else:
        return len(parsed[0]) >= 2


def load(resource):
    """
    open a file or URL for reading.  If the passed resource string is not a URL,
    or begins with 'file://', return a ``file``.  Otherwise, return the
    result of urllib.urlopen()
    """

    # handle file URLs separately due to python stdlib limitations
    if resource.startswith('file://'):
        resource = resource[len('file://'):]

    if not is_url(resource):
        # if no scheme is given, it is a file path
        return open(resource)

    return urllib.request.urlopen(resource)
