"""Various utility functions"""
# Copyright (C) 2006-2007 Red Hat, Inc.
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the
# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.

"""
UNSTABLE. We have been adding helpers randomly to this module.
"""

import os
import time
import hashlib
import random
import binascii
import gettext
import tempfile
import logging
import atexit

from gettext import gettext as _


def printable_hash(in_hash):
    """Convert binary hash data into printable characters."""
    printable = ""
    for char in in_hash:
        printable = printable + binascii.b2a_hex(char)
    return printable


def sha_data(data):
    """sha1 hash some bytes."""
    sha_hash = hashlib.sha1()
    sha_hash.update(data)
    return sha_hash.digest()


def unique_id(data=''):
    """Generate a likely-unique ID for whatever purpose

    data -- suffix appended to working data before hashing

    Returns a 40-character string with hexidecimal digits
    representing an SHA hash of the time, a random digit
    within a constrained range and the data passed.

    Note: these are *not* crypotographically secure or
        globally unique identifiers.  While they are likely
        to be unique-enough, no attempt is made to make
        perfectly unique values.
    """
    data_string = '%s%s%s' % (time.time(), random.randint(10000, 100000), data)
    return printable_hash(sha_data(data_string))


ACTIVITY_ID_LEN = 40


def is_hex(s):
    try:
        int(s, 16)
    except ValueError:
        return False

    return True


def validate_activity_id(actid):
    """Validate an activity ID."""
    if not isinstance(actid, (str, unicode)):
        return False
    if len(actid) != ACTIVITY_ID_LEN:
        return False
    if not is_hex(actid):
        return False
    return True


def set_proc_title(title):
    """Sets the process title so ps and top show more
       descriptive names.  This does not modify argv[0]
       and only the first 15 characters will be shown.

       title -- the title you wish to change the process
                title to

       Returns True on success.  We don't raise exceptions
       because if something goes wrong here it is not a big
       deal as this is intended as a nice thing to have for
       debugging
    """
    try:
        import ctypes
        libc = ctypes.CDLL('libc.so.6')
        libc.prctl(15, str(title), 0, 0, 0)

        return True
    except Exception:
        return False


class Node(object):

    __slots__ = ['prev', 'next', 'me']

    def __init__(self, prev, me):
        self.prev = prev
        self.me = me
        self.next = None


class LRU:
    """
    Implementation of a length-limited O(1) LRU queue.
    Built for and used by PyPE:
    http://pype.sourceforge.net
    Copyright 2003 Josiah Carlson.
    """

    def __init__(self, count, pairs=[]):
        # pylint: disable=W0102,W0612
        self.count = max(count, 1)
        self.d = {}
        self.first = None
        self.last = None
        for key, value in pairs:
            self[key] = value

    def __contains__(self, obj):
        return obj in self.d

    def __getitem__(self, obj):
        a = self.d[obj].me
        self[a[0]] = a[1]
        return a[1]

    def __setitem__(self, obj, val):
        if obj in self.d:
            del self[obj]
        nobj = Node(self.last, (obj, val))
        if self.first is None:
            self.first = nobj
        if self.last:
            self.last.next = nobj
        self.last = nobj
        self.d[obj] = nobj
        if len(self.d) > self.count:
            if self.first == self.last:
                self.first = None
                self.last = None
                return
            a = self.first
            a.next.prev = None
            self.first = a.next
            a.next = None
            del self.d[a.me[0]]
            del a

    def __delitem__(self, obj):
        nobj = self.d[obj]
        if nobj.prev:
            nobj.prev.next = nobj.next
        else:
            self.first = nobj.next
        if nobj.next:
            nobj.next.prev = nobj.prev
        else:
            self.last = nobj.prev
        del self.d[obj]

    def __iter__(self):
        cur = self.first
        while cur is not None:
            cur2 = cur.next
            yield cur.me[1]
            cur = cur2

    def iteritems(self):
        cur = self.first
        while cur is not None:
            cur2 = cur.next
            yield cur.me
            cur = cur2

    def iterkeys(self):
        return iter(self.d)

    def itervalues(self):
        for i_, j in self.iteritems():
            yield j

    def keys(self):
        return self.d.keys()


units = [['%d year', '%d years', 356 * 24 * 60 * 60],
         ['%d month', '%d months', 30 * 24 * 60 * 60],
         ['%d week', '%d weeks', 7 * 24 * 60 * 60],
         ['%d day', '%d days', 24 * 60 * 60],
         ['%d hour', '%d hours', 60 * 60],
         ['%d minute', '%d minutes', 60]]

AND = _(' and ')
COMMA = _(', ')

# TRANS: Indicating something that just happened, eg. "just now", "moments ago"
NOW = _('Seconds ago')

# TRANS: Indicating time passed, eg. "[10 day, 5 hours] ago",
# "[2 minutes] in the past", or "[3 years, 1 month] earlier"
ELAPSED = _('%s ago')

# Explanation of the following hack:
# The xgettext utility extracts plural forms by reading the strings included as
# parameters of ngettext(). As our plurals are not passed to ngettext()
# straight away because there needs to be a calculation before we know which
# strings need to be used, then we need to call ngettext() in a fake way so
# xgettext will pick them up as plurals.


def ngettext(singular, plural, n):
    pass


# TRANS: Relative dates (eg. 1 month and 5 days).
ngettext('%d year', '%d years', 1)
ngettext('%d month', '%d months', 1)
ngettext('%d week', '%d weeks', 1)
ngettext('%d day', '%d days', 1)
ngettext('%d hour', '%d hours', 1)
ngettext('%d minute', '%d minutes', 1)

del ngettext

# End of plurals hack


# gettext perfs hack (#7959)
_i18n_timestamps_cache = LRU(60)


def timestamp_to_elapsed_string(timestamp, max_levels=2):
    levels = 0
    time_period = ''
    elapsed_seconds = int(time.time() - timestamp)

    for name_singular, name_plural, factor in units:
        elapsed_units = elapsed_seconds / factor
        if elapsed_units > 0:

            if levels > 0:
                time_period += COMMA

            key = ''.join((os.environ['LANG'], name_singular,
                           str(elapsed_units)))
            if key in _i18n_timestamps_cache:
                time_period += _i18n_timestamps_cache[key]
            else:
                tmp = gettext.ngettext(name_singular,
                                       name_plural,
                                       elapsed_units)
                # FIXME: This is a hack so we don't crash when a translation
                # doesn't contain the expected number of placeholders (#2354)
                try:
                    translation = tmp % elapsed_units
                except TypeError:
                    translation = tmp

                _i18n_timestamps_cache[key] = translation
                time_period += translation

            elapsed_seconds -= elapsed_units * factor

        if time_period != '':
            levels += 1

        if levels == max_levels:
            break

    if levels == 0:
        return NOW

    return ELAPSED % time_period


_tracked_paths = {}


class TempFilePath(str):

    def __new__(cls, path=None):
        if path is None:
            fd, path = tempfile.mkstemp()
            os.close(fd)
        logging.debug('TempFilePath created %r', path)

        if path in _tracked_paths:
            _tracked_paths[path] += 1
        else:
            _tracked_paths[path] = 1

        return str.__new__(cls, path)

    def __del__(self):
        if _tracked_paths[self] == 1:
            del _tracked_paths[self]

            if os.path.exists(self):
                os.unlink(self)
                logging.debug('TempFilePath deleted %r', self)
            else:
                logging.warning('TempFilePath already deleted %r', self)
        else:
            _tracked_paths[self] -= 1


def _cleanup_temp_files():
    logging.debug('_cleanup_temp_files')
    for path in _tracked_paths.keys():
        try:
            os.unlink(path)
        except:
            # pylint: disable=W0702
            logging.exception('Exception occured in _cleanup_temp_files')

atexit.register(_cleanup_temp_files)


def format_size(size):
    if not size:
        return _('Empty')
    elif size < 1024:
        return _('%d B') % size
    elif size < 1024 ** 2:
        return _('%d KB') % (size / 1024)
    elif size < 1024 ** 3:
        return _('%d MB') % (size / 1024 ** 2)
    else:
        return _('%d GB') % (size / 1024 ** 3)