#
# Copyright 2014 Red Hat, Inc.
#
# This program 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.
#
# 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#
# Refer to the README and COPYING files for full details of the license
#

## most of the code is copied from vdsm project

import logging
import subprocess
from cpopen import CPopen
import io
import select
import threading
from StringIO import StringIO
from weakref import proxy
import time
import os
import errno
import signal
from collections import defaultdict
import xml.etree.cElementTree as ET


class HostStatus:
    UP = 'UP'
    DOWN = 'DOWN'
    UNREACHABLE = 'UNREACHABLE'


class HostStatusCode:
    UP = 0
    DOWN = 1
    UNREACHABLE = 2


class PluginStatus:
    OK = 'OK'
    WARNING = 'WARNING'
    CRITICAL = 'CRITICAL'
    UNKNOWN = 'UNKNOWN'


class PluginStatusCode:
    OK = 0
    WARNING = 1
    CRITICAL = 2
    UNKNOWN = 3


class CommandPath(object):
    def __init__(self, name, *args):
        self.name = name
        self.paths = args
        self._cmd = None

    @property
    def cmd(self):
        if not self._cmd:
            for path in self.paths:
                if os.path.exists(path):
                    self._cmd = path
                    break
            else:
                raise OSError(os.errno.ENOENT,
                              os.strerror(os.errno.ENOENT) + ': ' + self.name)
        return self._cmd

    def __repr__(self):
        return str(self.cmd)

    def __str__(self):
        return str(self.cmd)

    def __unicode__(self):
        return unicode(self.cmd)


ioniceCmdPath = CommandPath("ionice",
                            "/bin/ionice",
                            )
killCmdPath = CommandPath("kill",
                          "/bin/kill",
                          )
niceCmdPath = CommandPath("nice",
                          "/bin/nice",
                          )
setsidCmdPath = CommandPath("setsid",
                            "/bin/setsid",
                            )
sudoCmdPath = CommandPath("sudo",
                          "/usr/bin/sudo",
                          )
hostnameCmdPath = CommandPath("hostname", "/bin/hostname", )
glusterCmdPath = CommandPath("gluster", "/usr/sbin/gluster")
trapCmdPath = CommandPath("snmptrap", "/usr/bin/snmptrap")
# Buffsize is 1K because I tested it on some use cases and 1K was fastest. If
# you find this number to be a bottleneck in any way you are welcome to change
# it
BUFFSIZE = 1024
SUDO_NON_INTERACTIVE_FLAG = "-n"


# NOTE: it would be best to try and unify NoIntrCall and NoIntrPoll.
# We could do so defining a new object that can be used as a placeholer
# for the changing timeout value in the *args/**kwargs. This would
# lead us to rebuilding the function arguments at each loop.
def NoIntrPoll(pollfun, timeout=-1):
    """
    This wrapper is used to handle the interrupt exceptions that might
    occur during a poll system call. The wrapped function must be defined
    as poll([timeout]) where the special timeout value 0 is used to return
    immediately and -1 is used to wait indefinitely.
    """
    # When the timeout < 0 we shouldn't compute a new timeout after an
    # interruption.
    endtime = None if timeout < 0 else time.time() + timeout

    while True:
        try:
            return pollfun(timeout)
        except (IOError, select.error) as e:
            if e.args[0] != errno.EINTR:
                raise

        if endtime is not None:
            timeout = max(0, endtime - time.time())


class AsyncProc(object):
    """
    AsyncProc is a funky class. It wraps a standard subprocess.Popen
    Object and gives it super powers. Like the power to read from a stream
    without the fear of deadlock. It does this by always sampling all
    stream while waiting for data. By doing this the other process can freely
    write data to all stream without the fear of it getting stuck writing
    to a full pipe.
    """
    class _streamWrapper(io.RawIOBase):
        def __init__(self, parent, streamToWrap, fd):
            io.IOBase.__init__(self)
            self._stream = streamToWrap
            self._parent = proxy(parent)
            self._fd = fd
            self._closed = False

        def close(self):
            if not self._closed:
                self._closed = True
                while not self._streamClosed:
                    self._parent._processStreams()

        @property
        def closed(self):
            return self._closed

        @property
        def _streamClosed(self):
            return (self.fileno() in self._parent._closedfds)

        def fileno(self):
            return self._fd

        def seekable(self):
            return False

        def readable(self):
            return True

        def writable(self):
            return True

        def _readNonBlock(self, length):
            hasNewData = (self._stream.len - self._stream.pos)
            if hasNewData < length and not self._streamClosed:
                self._parent._processStreams()

            with self._parent._streamLock:
                res = self._stream.read(length)
                if self._stream.pos == self._stream.len:
                    self._stream.truncate(0)

            if res == "" and not self._streamClosed:
                return None
            else:
                return res

        def read(self, length):
            if not self._parent.blocking:
                return self._readNonBlock(length)
            else:
                res = None
                while res is None:
                    res = self._readNonBlock(length)

                return res

        def readinto(self, b):
            data = self.read(len(b))
            if data is None:
                return None

            bytesRead = len(data)
            b[:bytesRead] = data

            return bytesRead

        def write(self, data):
            if hasattr(data, "tobytes"):
                data = data.tobytes()
            with self._parent._streamLock:
                oldPos = self._stream.pos
                self._stream.pos = self._stream.len
                self._stream.write(data)
                self._stream.pos = oldPos

            while self._stream.len > 0 and not self._streamClosed:
                self._parent._processStreams()

            if self._streamClosed:
                self._closed = True

            if self._stream.len != 0:
                raise IOError(errno.EPIPE,
                              "Could not write all data to stream")

            return len(data)

    def __init__(self, popenToWrap):
        self._streamLock = threading.Lock()
        self._proc = popenToWrap

        self._stdout = StringIO()
        self._stderr = StringIO()
        self._stdin = StringIO()

        fdout = self._proc.stdout.fileno()
        fderr = self._proc.stderr.fileno()
        self._fdin = self._proc.stdin.fileno()

        self._closedfds = []

        self._poller = select.epoll()
        self._poller.register(fdout, select.EPOLLIN | select.EPOLLPRI)
        self._poller.register(fderr, select.EPOLLIN | select.EPOLLPRI)
        self._poller.register(self._fdin, 0)
        self._fdMap = {fdout: self._stdout,
                       fderr: self._stderr,
                       self._fdin: self._stdin}

        self.stdout = io.BufferedReader(self._streamWrapper(self,
                                        self._stdout, fdout), BUFFSIZE)

        self.stderr = io.BufferedReader(self._streamWrapper(self,
                                        self._stderr, fderr), BUFFSIZE)

        self.stdin = io.BufferedWriter(self._streamWrapper(self,
                                       self._stdin, self._fdin), BUFFSIZE)

        self._returncode = None

        self.blocking = False

    def _processStreams(self):
        if len(self._closedfds) == 3:
            return

        if not self._streamLock.acquire(False):
            self._streamLock.acquire()
            self._streamLock.release()
            return
        try:
            if self._stdin.len > 0 and self._stdin.pos == 0:
                # Polling stdin is redundant if there is nothing to write
                # turn on only if data is waiting to be pushed
                self._poller.modify(self._fdin, select.EPOLLOUT)

            pollres = NoIntrPoll(self._poller.poll, 1)

            for fd, event in pollres:
                stream = self._fdMap[fd]
                if event & select.EPOLLOUT and self._stdin.len > 0:
                    buff = self._stdin.read(BUFFSIZE)
                    written = os.write(fd, buff)
                    stream.pos -= len(buff) - written
                    if stream.pos == stream.len:
                        stream.truncate(0)
                        self._poller.modify(fd, 0)

                elif event & (select.EPOLLIN | select.EPOLLPRI):
                    data = os.read(fd, BUFFSIZE)
                    oldpos = stream.pos
                    stream.pos = stream.len
                    stream.write(data)
                    stream.pos = oldpos

                elif event & (select.EPOLLHUP | select.EPOLLERR):
                    self._poller.unregister(fd)
                    self._closedfds.append(fd)
                    # I don't close the fd because the original Popen
                    # will do it.

            if self.stdin.closed and self._fdin not in self._closedfds:
                self._poller.unregister(self._fdin)
                self._closedfds.append(self._fdin)
                self._proc.stdin.close()

        finally:
            self._streamLock.release()

    @property
    def pid(self):
        return self._proc.pid

    @property
    def returncode(self):
        if self._returncode is None:
            self._returncode = self._proc.poll()
        return self._returncode

    def kill(self):
        try:
            self._proc.kill()
        except OSError as ex:
            if ex.errno != errno.EPERM:
                raise
            execCmd([killCmdPath.cmd, "-%d" % (signal.SIGTERM,),
                    str(self.pid)], sudo=True)

    def wait(self, timeout=None, cond=None):
        startTime = time.time()
        while self.returncode is None:
            if timeout is not None and (time.time() - startTime) > timeout:
                return False
            if cond is not None and cond():
                return False
            self._processStreams()
        return True

    def communicate(self, data=None):
        if data is not None:
            self.stdin.write(data)
            self.stdin.flush()
        self.stdin.close()

        self.wait()
        return "".join(self.stdout), "".join(self.stderr)

    def __del__(self):
        self._poller.close()


def execCmd(command, sudo=False, cwd=None, data=None, raw=False, logErr=True,
            printable=None, env=None, sync=True, nice=None, ioclass=None,
            ioclassdata=None, setsid=False, execCmdLogger=logging.root,
            deathSignal=0, childUmask=None):
    """
    Executes an external command, optionally via sudo.

    IMPORTANT NOTE: the new process would receive `deathSignal` when the
    controlling thread dies, which may not be what you intended: if you create
    a temporary thread, spawn a sync=False sub-process, and have the thread
    finish, the new subprocess would die immediately.
    """
    if ioclass is not None:
        cmd = command
        command = [ioniceCmdPath.cmd, '-c', str(ioclass)]
        if ioclassdata is not None:
            command.extend(("-n", str(ioclassdata)))

        command = command + cmd

    if nice is not None:
        command = [niceCmdPath.cmd, '-n', str(nice)] + command

    if setsid:
        command = [setsidCmdPath.cmd] + command

    if sudo:
        command = [sudoCmdPath.cmd, SUDO_NON_INTERACTIVE_FLAG] + command

    if not printable:
        printable = command

    cmdline = repr(subprocess.list2cmdline(printable))
    execCmdLogger.debug("%s (cwd %s)", cmdline, cwd)

    p = CPopen(command, close_fds=True, cwd=cwd, env=env,
               deathSignal=deathSignal, childUmask=childUmask)
    p = AsyncProc(p)
    if not sync:
        if data is not None:
            p.stdin.write(data)
            p.stdin.flush()

        return p

    (out, err) = p.communicate(data)

    if out is None:
        # Prevent splitlines() from barfing later on
        out = ""

    execCmdLogger.debug("%s: <err> = %s; <rc> = %d",
                        {True: "SUCCESS", False: "FAILED"}[p.returncode == 0],
                        repr(err), p.returncode)

    if not raw:
        out = out.splitlines(False)
        err = err.splitlines(False)

    return (p.returncode, out, err)


def retry(func, expectedException=Exception, tries=None,
          timeout=None, sleep=1, stopCallback=None):
    """
    Retry a function. Wraps the retry logic so you don't have to
    implement it each time you need it.

    :param func: The callable to run.
    :param expectedException: The exception you expect to receive when the
                              function fails.
    :param tries: The number of times to try. None\0,-1 means infinite.
    :param timeout: The time you want to spend waiting. This **WILL NOT** stop
                    the method. It will just not run it if it ended after the
                    timeout.
    :param sleep: Time to sleep between calls in seconds.
    :param stopCallback: A function that takes no parameters and causes the
                         method to stop retrying when it returns with a
                         positive value.
    """
    if tries in [0, None]:
        tries = -1

    if timeout in [0, None]:
        timeout = -1

    startTime = time.time()

    while True:
        tries -= 1
        try:
            return func()
        except expectedException:
            if tries == 0:
                raise

            if (timeout > 0) and ((time.time() - startTime) > timeout):
                raise

            if stopCallback is not None and stopCallback():
                raise

            time.sleep(sleep)


def xml2dict(tree):
    d = {tree.tag: {} if tree.attrib else None}
    children = list(tree)
    if children:
        dd = defaultdict(list)
        for dc in map(xml2dict, children):
            for k, v in dc.iteritems():
                dd[k].append(v)
        d = {tree.tag: {}}
        for k, v in dd.iteritems():
            d[tree.tag][k] = v[0] if len(v) == 1 else v
    if tree.attrib:
        d[tree.tag].update((k, v) for k, v in tree.attrib.iteritems())
    if tree.text:
        text = tree.text.strip()
        if children or tree.attrib:
            if text:
                d[tree.tag]['#text'] = text
        else:
            d[tree.tag] = text
    return d


def convertSize(val, unitFrom, unitTo):
    ''' Convert size from one unit to another
    For example, KB to MB
    '''
    units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']
    unitFromIndex = units.index(unitFrom)
    unitToIndex = units.index(unitTo)

    if unitFromIndex < unitToIndex:
        convFactor = 1 << (unitToIndex - unitFromIndex) * 10
        return float(val) / convFactor
    if unitFromIndex > unitToIndex:
        convFactor = 1 << (unitFromIndex - unitToIndex) * 10
        return float(val) * convFactor
    return val


def parseXml(xmldoc, searchStr):
    root = ET.fromstring(xmldoc)
    statusStr = root.findall(searchStr)
    return statusStr


def getsnmpmanagers(path):
    listofmanagers = []
    with open(path, "r") as mangerconfig:
        for line in mangerconfig.readlines():
            if line.startswith("#"):
                continue
            config = line.split()
            if len(config) == 2:
                listofmanagers.\
                    append({'host': config[0], 'community': config[1]})
    return listofmanagers