# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
System-level utilities and helper functions.
"""

import datetime
import inspect
import json
import os
import random
import subprocess
import socket
import struct
import sys
import time
from xml.sax import saxutils
import re
import netaddr

from eventlet import event
from eventlet import greenthread

from nova import exception
from nova.exception import ProcessExecutionError
from nova import log as logging


LOG = logging.getLogger("nova.utils")
TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"


def import_class(import_str):
    """Returns a class from a string including module and class"""
    mod_str, _sep, class_str = import_str.rpartition('.')
    try:
        __import__(mod_str)
        return getattr(sys.modules[mod_str], class_str)
    except (ImportError, ValueError, AttributeError), exc:
        logging.debug(_('Inner Exception: %s'), exc)
        raise exception.NotFound(_('Class %s cannot be found') % class_str)


def import_object(import_str):
    """Returns an object including a module or module and class"""
    try:
        __import__(import_str)
        return sys.modules[import_str]
    except ImportError:
        cls = import_class(import_str)
        return cls()


def vpn_ping(address, port, timeout=0.05, session_id=None):
    """Sends a vpn negotiation packet and returns the server session.

    Returns False on a failure. Basic packet structure is below.

    Client packet (14 bytes)::
     0 1      8 9  13
    +-+--------+-----+
    |x| cli_id |?????|
    +-+--------+-----+
    x = packet identifier 0x38
    cli_id = 64 bit identifier
    ? = unknown, probably flags/padding

    Server packet (26 bytes)::
     0 1      8 9  13 14    21 2225
    +-+--------+-----+--------+----+
    |x| srv_id |?????| cli_id |????|
    +-+--------+-----+--------+----+
    x = packet identifier 0x40
    cli_id = 64 bit identifier
    ? = unknown, probably flags/padding
    bit 9 was 1 and the rest were 0 in testing
    """
    if session_id is None:
        session_id = random.randint(0, 0xffffffffffffffff)
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    data = struct.pack("!BQxxxxxx", 0x38, session_id)
    sock.sendto(data, (address, port))
    sock.settimeout(timeout)
    try:
        received = sock.recv(2048)
    except socket.timeout:
        return False
    finally:
        sock.close()
    fmt = "!BQxxxxxQxxxx"
    if len(received) != struct.calcsize(fmt):
        print struct.calcsize(fmt)
        return False
    (identifier, server_sess, client_sess) = struct.unpack(fmt, received)
    if identifier == 0x40 and client_sess == session_id:
        return server_sess


def fetchfile(url, target):
    LOG.debug(_("Fetching %s") % url)
#    c = pycurl.Curl()
#    fp = open(target, "wb")
#    c.setopt(c.URL, url)
#    c.setopt(c.WRITEDATA, fp)
#    c.perform()
#    c.close()
#    fp.close()
    execute("curl --fail %s -o %s" % (url, target))


def execute(cmd, process_input=None, addl_env=None, check_exit_code=True):
    LOG.debug(_("Running cmd (subprocess): %s"), cmd)
    env = os.environ.copy()
    if addl_env:
        env.update(addl_env)
    obj = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE,
        stdout=subprocess.PIPE, stderr=subprocess.PIPE, env=env)
    result = None
    if process_input != None:
        result = obj.communicate(process_input)
    else:
        result = obj.communicate()
    obj.stdin.close()
    if obj.returncode:
        LOG.debug(_("Result was %s") % obj.returncode)
        if check_exit_code and obj.returncode != 0:
            (stdout, stderr) = result
            raise ProcessExecutionError(exit_code=obj.returncode,
                                        stdout=stdout,
                                        stderr=stderr,
                                        cmd=cmd)
    # NOTE(termie): this appears to be necessary to let the subprocess call
    #               clean something up in between calls, without it two
    #               execute calls in a row hangs the second one
    greenthread.sleep(0)
    return result


def abspath(s):
    return os.path.join(os.path.dirname(__file__), s)


def novadir():
    import nova
    return os.path.abspath(nova.__file__).split('nova/__init__.pyc')[0]


def default_flagfile(filename='nova.conf'):
    for arg in sys.argv:
        if arg.find('flagfile') != -1:
            break
    else:
        if not os.path.isabs(filename):
            # turn relative filename into an absolute path
            script_dir = os.path.dirname(inspect.stack()[-1][1])
            filename = os.path.abspath(os.path.join(script_dir, filename))
        if os.path.exists(filename):
            flagfile = ['--flagfile=%s' % filename]
            sys.argv = sys.argv[:1] + flagfile + sys.argv[1:]


def debug(arg):
    LOG.debug(_('debug in callback: %s'), arg)
    return arg


def runthis(prompt, cmd, check_exit_code=True):
    LOG.debug(_("Running %s"), (cmd))
    rv, err = execute(cmd, check_exit_code=check_exit_code)


def generate_uid(topic, size=8):
    characters = '01234567890abcdefghijklmnopqrstuvwxyz'
    choices = [random.choice(characters) for x in xrange(size)]
    return '%s-%s' % (topic, ''.join(choices))


def generate_mac():
    mac = [0x02, 0x16, 0x3e,
           random.randint(0x00, 0x7f),
           random.randint(0x00, 0xff),
           random.randint(0x00, 0xff)]
    return ':'.join(map(lambda x: "%02x" % x, mac))


def last_octet(address):
    return int(address.split(".")[-1])


def  get_my_linklocal(interface):
    try:
        if_str = execute("ip -f inet6 -o addr show %s" % interface)
        condition = "\s+inet6\s+([0-9a-f:]+/\d+)\s+scope\s+link"
        links = [re.search(condition, x) for x in if_str[0].split('\n')]
        address = [w.group(1) for w in links if w is not None]
        if address[0] is not None:
            return address[0]
        else:
            return 'fe00::'
    except IndexError as ex:
        LOG.warn(_("Couldn't get Link Local IP of %(interface)s :%(ex)s")
                % locals())
    except ProcessExecutionError as ex:
        LOG.warn(_("Couldn't get Link Local IP of %(interface)s :%(ex)s")
                % locals())
    except:
        return 'fe00::'


def to_global_ipv6(prefix, mac):
    mac64 = netaddr.EUI(mac).eui64().words
    int_addr = int(''.join(['%02x' % i for i in mac64]), 16)
    mac64_addr = netaddr.IPAddress(int_addr)
    maskIP = netaddr.IPNetwork(prefix).ip
    return (mac64_addr ^ netaddr.IPAddress('::0200:0:0:0') | maskIP).format()


def to_mac(ipv6_address):
    address = netaddr.IPAddress(ipv6_address)
    mask1 = netaddr.IPAddress("::ffff:ffff:ffff:ffff")
    mask2 = netaddr.IPAddress("::0200:0:0:0")
    mac64 = netaddr.EUI(int(address & mask1 ^ mask2)).words
    return ":".join(["%02x" % i for i in mac64[0:3] + mac64[5:8]])


def utcnow():
    """Overridable version of datetime.datetime.utcnow."""
    if utcnow.override_time:
        return utcnow.override_time
    return datetime.datetime.utcnow()


utcnow.override_time = None


def utcnow_ts():
    """Timestamp version of our utcnow function."""
    return time.mktime(utcnow().timetuple())


def set_time_override(override_time=datetime.datetime.utcnow()):
    """Override utils.utcnow to return a constant time."""
    utcnow.override_time = override_time


def advance_time_delta(timedelta):
    """Advance overriden time using a datetime.timedelta."""
    assert(not utcnow.override_time is None)
    utcnow.override_time += timedelta


def advance_time_seconds(seconds):
    """Advance overriden time by seconds."""
    advance_time_delta(datetime.timedelta(0, seconds))


def clear_time_override():
    """Remove the overridden time."""
    utcnow.override_time = None


def isotime(at=None):
    """Returns iso formatted utcnow."""
    if not at:
        at = utcnow()
    return at.strftime(TIME_FORMAT)


def parse_isotime(timestr):
    """Turn an iso formatted time back into a datetime"""
    return datetime.datetime.strptime(timestr, TIME_FORMAT)


def parse_mailmap(mailmap='.mailmap'):
    mapping = {}
    if os.path.exists(mailmap):
        fp = open(mailmap, 'r')
        for l in fp:
            l = l.strip()
            if not l.startswith('#') and ' ' in l:
                canonical_email, alias = l.split(' ')
                mapping[alias] = canonical_email
    return mapping


def str_dict_replace(s, mapping):
    for s1, s2 in mapping.iteritems():
        s = s.replace(s1, s2)
    return s


class LazyPluggable(object):
    """A pluggable backend loaded lazily based on some value."""

    def __init__(self, pivot, **backends):
        self.__backends = backends
        self.__pivot = pivot
        self.__backend = None

    def __get_backend(self):
        if not self.__backend:
            backend_name = self.__pivot.value
            if backend_name not in self.__backends:
                raise exception.Error(_('Invalid backend: %s') % backend_name)

            backend = self.__backends[backend_name]
            if type(backend) == type(tuple()):
                name = backend[0]
                fromlist = backend[1]
            else:
                name = backend
                fromlist = backend

            self.__backend = __import__(name, None, None, fromlist)
            LOG.debug(_('backend %s'), self.__backend)
        return self.__backend

    def __getattr__(self, key):
        backend = self.__get_backend()
        return getattr(backend, key)


class LoopingCallDone(Exception):
    """The poll-function passed to LoopingCall can raise this exception to
    break out of the loop normally. This is somewhat analogous to
    StopIteration.

    An optional return-value can be included as the argument to the exception;
    this return-value will be returned by LoopingCall.wait()
    """

    def __init__(self, retvalue=True):
        """:param retvalue: Value that LoopingCall.wait() should return"""
        self.retvalue = retvalue


class LoopingCall(object):
    def __init__(self, f=None, *args, **kw):
        self.args = args
        self.kw = kw
        self.f = f
        self._running = False

    def start(self, interval, now=True):
        self._running = True
        done = event.Event()

        def _inner():
            if not now:
                greenthread.sleep(interval)
            try:
                while self._running:
                    self.f(*self.args, **self.kw)
                    greenthread.sleep(interval)
            except LoopingCallDone, e:
                self.stop()
                done.send(e.retvalue)
            except Exception:
                logging.exception('in looping call')
                done.send_exception(*sys.exc_info())
                return
            else:
                done.send(True)

        self.done = done

        greenthread.spawn(_inner)
        return self.done

    def stop(self):
        self._running = False

    def wait(self):
        return self.done.wait()


def xhtml_escape(value):
    """Escapes a string so it is valid within XML or XHTML.

    Code is directly from the utf8 function in
    http://github.com/facebook/tornado/blob/master/tornado/escape.py

    """
    return saxutils.escape(value, {'"': "&quot;"})


def utf8(value):
    """Try to turn a string into utf-8 if possible.

    Code is directly from the utf8 function in
    http://github.com/facebook/tornado/blob/master/tornado/escape.py

    """
    if isinstance(value, unicode):
        return value.encode("utf-8")
    assert isinstance(value, str)
    return value


def to_primitive(value):
    if type(value) is type([]) or type(value) is type((None,)):
        o = []
        for v in value:
            o.append(to_primitive(v))
        return o
    elif type(value) is type({}):
        o = {}
        for k, v in value.iteritems():
            o[k] = to_primitive(v)
        return o
    elif isinstance(value, datetime.datetime):
        return str(value)
    elif hasattr(value, 'iteritems'):
        return to_primitive(dict(value.iteritems()))
    elif hasattr(value, '__iter__'):
        return to_primitive(list(value))
    else:
        return value


def dumps(value):
    try:
        return json.dumps(value)
    except TypeError:
        pass
    return json.dumps(to_primitive(value))


def loads(s):
    return json.loads(s)
