#!/usr/bin/env python

'''The XML-RPC Bcfg2 Server'''
__revision__ = '$Revision:$'

from getopt import getopt, GetoptError
from sys import argv, exc_info
from syslog import openlog, LOG_LOCAL0, syslog, LOG_INFO, LOG_ERR
from Bcfg2.Server.Core import Core, CoreInitError
from Bcfg2.Server.Metadata import MetadataConsistencyError
from Bcfg2.Server.Component import Component
from threading import Lock
from select import select, error as selecterror
from signal import signal, SIGINT, SIGTERM
from traceback import extract_tb
from xmlrpclib import Fault
from socket import gethostbyaddr, herror
from lxml.etree import XML, Element, tostring
from M2Crypto.SSL import SSLError

import os, sys

def daemonize(filename):
    '''Do the double fork/setsession dance'''
    # Fork once
    if os.fork() != 0:      
        os._exit(0)         
    os.setsid()                     # Create new session
    pid = os.fork()
    if pid != 0:
        pidfile = open(filename, "w")
        pidfile.write("%i" % pid)
        pidfile.close()
        os._exit(0)     
    os.chdir("/")         
    os.umask(0)

    null = open("/dev/null", "w+")

    os.dup2(null.fileno(), sys.__stdin__.fileno())
    os.dup2(null.fileno(), sys.__stdout__.fileno())
    os.dup2(null.fileno(), sys.__stderr__.fileno())


def critical_error(operation):
    '''Print tracebacks in unexpected cases'''
    syslog(LOG_ERR, "Traceback information (please include in any bug report):")
    (ttype, value, trace) = exc_info()
    for line in extract_tb(trace):        
        syslog(LOG_ERR, "File %s, line %i, in %s\n   %s" % (line))
    syslog(LOG_ERR, "%s: %s" % (ttype, value))
    warning_error("An unexpected failure occurred in %s" % (operation) )
    raise Fault, (7, "Critical unexpected failure: %s" % (operation))

def fatal_error(message):
    '''Signal a fatal error'''
    syslog(LOG_ERR, "Fatal error: %s" % (message))
    raise SystemExit, 1

def warning_error(message):
    '''Warn about a problem but continue'''
    syslog(LOG_ERR,"Warning: %s\n" % (message))
           
def usage_error(message, opt, vopt, descs, argDescs):
    '''Die because script was called the wrong way'''
    print "Usage error: %s" % (message)
    print_usage(opt, vopt, descs, argDescs)
    raise SystemExit, 2

verboseMode = False

def verbose(message):
    '''Conditionally output information in verbose mode'''
    global verboseMode

    if(verboseMode == True):
        syslog(LOG_INFO, "%s" % (message))

def print_usage(opt, vopt, descs, argDescs):
    print "Bcfg2Server usage:"
    for arg in opt.iteritems():
        print " -%s\t\t\t%s" % (arg[0], descs[arg[0]])
    for arg in vopt.iteritems():
        print " -%s %s\t%s" % (arg[0], argDescs[arg[0]], descs[arg[0]])

def dgetopt(arglist, opt, vopt, descs, argDescs):
    '''parse options into a dictionary'''
    global verboseMode
    
    ret = {}
    for optname in opt.values() + vopt.values():
        ret[optname] = False
        
    gstr = "".join(opt.keys()) + "".join([optionkey + ':' for optionkey in vopt.keys()])
    try:
        ginfo = getopt(arglist, gstr)
    except GetoptError, gerr:
        usage_error(gerr, opt, vopt, descs, argDescs)

    for (gopt, garg) in ginfo[0]:
        option = gopt[1:]
        if opt.has_key(option):
            ret[opt[option]] = True
        else:
            ret[vopt[option]] = garg

    if ret["help"] == True:
        print_usage(opt, vopt, descs, argDescs)
        raise SystemExit, 0

    if ret["verbose"] == True:
        verboseMode = True
        
    return ret

class Bcfg2(Component):
    """The Bcfg2 Server component providing XML-RPC access to Bcfg methods"""
    __name__ = 'bcfg2'
    __implementation__ = 'bcfg2'

    request_queue_size = 15

    def __init__(self, setup):
        Component.__init__(self, setup)
        self.shut = False
        # set shutdown handlers for sigint and sigterm
        signal(SIGINT, self.start_shutdown)
        signal(SIGTERM, self.start_shutdown)
        try:
            self.Core = Core(setup, setup['configfile'])
            self.CoreLock = Lock()
        except CoreInitError, msg:
            fatal_error(msg)

        self.funcs.update({
            "GetConfig": self.Bcfg2GetConfig,
            "GetProbes": self.Bcfg2GetProbes,
            "RecvProbeData": self.Bcfg2RecvProbeData,
            "RecvStats": self.Bcfg2RecvStats
            })
        for plugin in self.Core.plugins.values():
            for method in plugin.__rmi__:
                self.register_function(getattr(self.Core.plugins[plugin.__name__], method),
                                       "%s.%s" % (plugin.__name__, method))

    def get_request(self):
        '''We need to do work between requests, so select with timeout instead of blocking in accept'''
        rsockinfo = []
        famfd = self.Core.fam.fileno()
        while self.socket not in rsockinfo:
            if self.shut:
                raise SSLError
            try:
                rsockinfo = select([self.socket, famfd], [], [], 15)[0]
            except selecterror:
                raise SSLError
            
            if famfd in rsockinfo:
                self.Core.fam.Service()
            if self.socket in rsockinfo:
                # workaround for m2crypto 0.15 bug
                self.socket.postConnectionCheck = None
                return self.socket.accept()

    def serve_forever(self):
        """Handle one request at a time until doomsday."""
        while not self.shut:
            self.handle_request()

    def start_shutdown(self, signum, frame):
        '''Shutdown on unexpected signals'''
        self.shut = True

    def handle_error(self):
        '''Catch error path for clean exit'''
        return False

    def resolve_client(self, client):
        try:
            return gethostbyaddr(client)[0]
        except herror:
            warning = "host resolution error for %s" % (client)
            warning_error(warning)
            raise Fault, (5, warning)
        
    def Bcfg2GetProbes(self, address):
        '''Fetch probes for a particular client'''
        client = self.resolve_client(address[0])
        resp = Element('probes')

        try:
            meta = self.Core.metadata.FetchMetadata(client)
            
            for generator in self.Core.generators:
                for probe in generator.GetProbes(meta):
                    resp.append(probe)
            return tostring(resp)
        except MetadataConsistencyError:
            warning = 'metadata consistency error'
            warning_error(warning)
            raise Fault, (6, warning)
        except:
            critical_error("determining client probes")


    def Bcfg2RecvProbeData(self, address, probedata):
        '''Receive probe data from clients'''
        client = self.resolve_client(address[0])

        for data in probedata:
            try:
                [generator] = [gen for gen in self.Core.generators if gen.__name__ == data.get('source')]
                generator.ReceiveData(client, data)
            except IndexError:
                warning_error("Failed to locate plugin %s" % (data.get('source')))
            except:
                critical_error("probe data receipt")
        return True

    def Bcfg2GetConfig(self, address, image=False, profile=False):
        '''Build config for a client'''
        client = self.resolve_client(address[0])

        if image and profile:
            try:
                self.Core.metadata.set_group(client, profile)
            except MetadataConsistencyError:
                warning = 'metadata consistency error'
                warning_error(warning)
                raise Fault, (6, warning)
        return tostring(self.Core.BuildConfiguration(client))

    def Bcfg2RecvStats(self, address, stats):
        '''Act on statistics upload'''
        sdata = XML(stats)
        state = sdata.find(".//Statistics")
        # Versioned stats to prevent tied client/server upgrade
        if state.get('version') >= '2.0':
            client = self.resolve_client(address[0])
            
            # Update statistics
            self.Core.stats.updateStats(sdata, client)

        verbose("Client %s reported state %s" % 
                (client, state.attrib['state']))
        return "<ok/>"

if __name__ == '__main__':
    openlog("Bcfg2", 0, LOG_LOCAL0)
    options =  {
        'v':'verbose',
        'd':'debug',
        'h':'help'
        }
    doptions = {
        'D':'daemon',
        'c':'configfile',
        'C':'client'
        }

    descriptions = {
        'v': "enable verbose output",
        'd': "enable debugging output",
        'D': "daemonise the server, storing PID",
        'c': "set the server's config file",
        'C': "always return the given client's config (debug only)",
        'h': "display this usage information"
        }

    argDescriptions = {
        'D': "<PID file>   ",
        'c': "<config file>",
        'C': "<client hostname>"
        }
    
    ssetup = dgetopt(argv[1:], options, doptions,
                     descriptions, argDescriptions)
    if ssetup['daemon']:
        daemonize(ssetup['daemon'])
    if not ssetup['configfile']:
        ssetup['configfile'] = '/etc/bcfg2.conf'
    s = Bcfg2(ssetup)
    while not s.shut:
        try:
            s.serve_forever()
        except:
            critical_error("service loop")

    syslog(LOG_INFO, "Shutting down")