""" A plugin to gather information from a client machine """

import re
import os
import sys
import time
import copy
import operator
import lxml.etree
import Bcfg2.Server
import Bcfg2.Server.Cache
import Bcfg2.Server.Plugin
import Bcfg2.Server.FileMonitor
from Bcfg2.Logger import Debuggable
from Bcfg2.Server.Statistics import track_statistics

HAS_DJANGO = False
# pylint: disable=C0103
ProbesDataModel = None
ProbesGroupsModel = None
# pylint: enable=C0103


def load_django_models():
    """ Load models for Django after option parsing has completed """
    # pylint: disable=W0602
    global ProbesDataModel, ProbesGroupsModel, HAS_DJANGO
    # pylint: enable=W0602
    try:
        from django.db import models
        HAS_DJANGO = True
    except ImportError:
        HAS_DJANGO = False
        return

    class ProbesDataModel(models.Model,  # pylint: disable=W0621,W0612
                          Bcfg2.Server.Plugin.PluginDatabaseModel):
        """ The database model for storing probe data """
        hostname = models.CharField(max_length=255)
        probe = models.CharField(max_length=255)
        timestamp = models.DateTimeField(auto_now=True)
        data = models.TextField(null=True)

    class ProbesGroupsModel(models.Model,  # pylint: disable=W0621,W0612
                            Bcfg2.Server.Plugin.PluginDatabaseModel):
        """ The database model for storing probe groups """
        hostname = models.CharField(max_length=255)
        group = models.CharField(max_length=255)


try:
    import json
    HAS_JSON = True
except ImportError:
    try:
        import simplejson as json
        HAS_JSON = True
    except ImportError:
        HAS_JSON = False

try:
    import yaml
    HAS_YAML = True
except ImportError:
    HAS_YAML = False


class ProbeStore(Debuggable):
    """ Caching abstraction layer between persistent probe data
    storage and the Probes plugin."""

    def __init__(self, core, datastore):  # pylint: disable=W0613
        Debuggable.__init__(self)
        self._groupcache = Bcfg2.Server.Cache.Cache("Probes", "probegroups")
        self._datacache = Bcfg2.Server.Cache.Cache("Probes", "probedata")

    def get_groups(self, hostname):
        """ Get the list of groups for the given host """
        if hostname not in self._groupcache:
            self._load_groups(hostname)
        return self._groupcache.get(hostname, [])

    def set_groups(self, hostname, groups):
        """ Set the list of groups for the given host """
        raise NotImplementedError

    def get_data(self, hostname):
        """ Get a dict of probe data for the given host """
        if hostname not in self._datacache:
            self._load_data(hostname)
        return self._datacache.get(hostname, dict())

    def set_data(self, hostname, data):
        """ Set probe data for the given host """
        raise NotImplementedError

    def _load_groups(self, hostname):
        """ When probe groups are not found in the cache, this
        function is called to load them from the backend (XML or
        database). """
        raise NotImplementedError

    def _load_data(self, hostname):
        """ When probe groups are not found in the cache, this
        function is called to load them from the backend (XML or
        database). """
        raise NotImplementedError

    def commit(self):
        """ Commit the current data in the cache to the persistent
        backend store. This is not used with the
        :class:`Bcfg2.Server.Plugins.Probes.DBProbeStore`, because it
        commits on every change. """
        pass


class DBProbeStore(ProbeStore, Bcfg2.Server.Plugin.DatabaseBacked):
    """ Caching abstraction layer between the database and the Probes
    plugin. """
    create = False

    def __init__(self, core, datastore):
        Bcfg2.Server.Plugin.DatabaseBacked.__init__(self, core, datastore)
        ProbeStore.__init__(self, core, datastore)

    def _load_groups(self, hostname):
        Bcfg2.Server.Cache.expire("Probes", "probegroups", hostname)
        groupdata = ProbesGroupsModel.objects.filter(hostname=hostname)
        self._groupcache[hostname] = list(set(r.group for r in groupdata))
        Bcfg2.Server.Cache.expire("Metadata", hostname)

    @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
    def set_groups(self, hostname, groups):
        Bcfg2.Server.Cache.expire("Probes", "probegroups", hostname)
        olddata = self._groupcache.get(hostname, [])
        self._groupcache[hostname] = groups
        for group in groups:
            try:
                ProbesGroupsModel.objects.get_or_create(
                    hostname=hostname,
                    group=group)
            except ProbesGroupsModel.MultipleObjectsReturned:
                ProbesGroupsModel.objects.filter(hostname=hostname,
                                                 group=group).delete()
                ProbesGroupsModel.objects.get_or_create(
                    hostname=hostname,
                    group=group)
        ProbesGroupsModel.objects.filter(
            hostname=hostname).exclude(group__in=groups).delete()
        if olddata != groups:
            Bcfg2.Server.Cache.expire("Metadata", hostname)

    def _load_data(self, hostname):
        Bcfg2.Server.Cache.expire("Probes", "probegroups", hostname)
        Bcfg2.Server.Cache.expire("Probes", "probedata", hostname)
        self._datacache[hostname] = ClientProbeDataSet()
        ts_set = False
        for pdata in ProbesDataModel.objects.filter(hostname=hostname):
            if not ts_set:
                self._datacache[hostname].timestamp = \
                    time.mktime(pdata.timestamp.timetuple())
                ts_set = True
            self._datacache[hostname][pdata.probe] = ProbeData(pdata.data)
        Bcfg2.Server.Cache.expire("Metadata", hostname)

    @Bcfg2.Server.Plugin.DatabaseBacked.get_db_lock
    def set_data(self, hostname, data):
        Bcfg2.Server.Cache.expire("Probes", "probedata", hostname)
        self._datacache[hostname] = ClientProbeDataSet()
        expire_metadata = False
        for probe, pdata in data.items():
            self._datacache[hostname][probe] = pdata
            record, created = ProbesDataModel.objects.get_or_create(
                hostname=hostname,
                probe=probe)
            expire_metadata |= created
            if record.data != pdata:
                record.data = pdata
                record.save()
                expire_metadata = True
        qset = ProbesDataModel.objects.filter(
            hostname=hostname).exclude(probe__in=data.keys())
        if len(qset):
            qset.delete()
            expire_metadata = True
        if expire_metadata:
            Bcfg2.Server.Cache.expire("Metadata", hostname)


class XMLProbeStore(ProbeStore):
    """ Caching abstraction layer between ``probed.xml`` and the
    Probes plugin."""
    def __init__(self, core, datastore):
        ProbeStore.__init__(self, core, datastore)
        self._fname = os.path.join(datastore, 'probed.xml')
        self._load_data()

    def _load_data(self, _=None):
        """ Load probe data from probed.xml """
        Bcfg2.Server.Cache.expire("Probes", "probegroups")
        Bcfg2.Server.Cache.expire("Probes", "probedata")
        if not os.path.exists(self._fname):
            self.commit()
        try:
            data = lxml.etree.parse(self._fname,
                                    parser=Bcfg2.Server.XMLParser).getroot()
        except (IOError, lxml.etree.XMLSyntaxError):
            err = sys.exc_info()[1]
            self.logger.error("Failed to read file probed.xml: %s" % err)
            return
        for client in data.getchildren():
            self._datacache[client.get('name')] = \
                ClientProbeDataSet(timestamp=client.get("timestamp"))
            self._groupcache[client.get('name')] = []
            for pdata in client:
                if pdata.tag == 'Probe':
                    self._datacache[client.get('name')][pdata.get('name')] = \
                        ProbeData(pdata.get("value"))
                elif pdata.tag == 'Group':
                    self._groupcache[client.get('name')].append(
                        pdata.get('name'))

        Bcfg2.Server.Cache.expire("Metadata")

    def _load_groups(self, hostname):
        self._load_data(hostname)

    def commit(self):
        """ Write received probe data to probed.xml """
        top = lxml.etree.Element("Probed")
        for client, probed in sorted(self._datacache.items()):
            # make a copy of probe data for this client in case it
            # submits probe data while we're trying to write
            # probed.xml
            probedata = copy.copy(probed)
            ctag = \
                lxml.etree.SubElement(top, 'Client', name=client,
                                      timestamp=str(int(probedata.timestamp)))
            for probe in sorted(probedata):
                lxml.etree.SubElement(
                    ctag, 'Probe', name=probe,
                    value=self._datacache[client][probe])
            for group in sorted(self._groupcache[client]):
                lxml.etree.SubElement(ctag, "Group", name=group)
        try:
            top.getroottree().write(self._fname,
                                    xml_declaration=False,
                                    pretty_print='true')
        except IOError:
            err = sys.exc_info()[1]
            self.logger.error("Failed to write probed.xml: %s" % err)

    def set_groups(self, hostname, groups):
        Bcfg2.Server.Cache.expire("Probes", "probegroups", hostname)
        olddata = self._groupcache.get(hostname, [])
        self._groupcache[hostname] = groups
        if olddata != groups:
            Bcfg2.Server.Cache.expire("Metadata", hostname)

    def set_data(self, hostname, data):
        Bcfg2.Server.Cache.expire("Probes", "probedata", hostname)
        self._datacache[hostname] = ClientProbeDataSet()
        expire_metadata = False
        for probe, pdata in data.items():
            olddata = self._datacache[hostname].get(probe, ProbeData(''))
            self._datacache[hostname][probe] = pdata
            expire_metadata |= olddata != data
        if expire_metadata:
            Bcfg2.Server.Cache.expire("Metadata", hostname)


class ClientProbeDataSet(dict):
    """ dict of probe => [probe data] that records a timestamp for
    each host """
    def __init__(self, *args, **kwargs):
        if "timestamp" in kwargs and kwargs['timestamp'] is not None:
            self.timestamp = kwargs.pop("timestamp")
        else:
            self.timestamp = time.time()
        dict.__init__(self, *args, **kwargs)


class ProbeData(str):  # pylint: disable=E0012,R0924
    """ a ProbeData object emulates a str object, but also has .xdata,
    .json, and .yaml properties to provide convenient ways to use
    ProbeData objects as XML, JSON, or YAML data """
    def __new__(cls, data):
        return str.__new__(cls, data)

    def __init__(self, data):  # pylint: disable=W0613
        str.__init__(self)
        self._xdata = None
        self._json = None
        self._yaml = None

    @property
    def data(self):
        """ provide backwards compatibility with broken ProbeData
        object in bcfg2 1.2.0 thru 1.2.2 """
        return str(self)

    @property
    def xdata(self):
        """ The probe data as a lxml.etree._Element document """
        if self._xdata is None:
            try:
                self._xdata = lxml.etree.XML(self.data,
                                             parser=Bcfg2.Server.XMLParser)
            except lxml.etree.XMLSyntaxError:
                pass
        return self._xdata

    @property
    def json(self):
        """ The probe data as a decoded JSON data structure """
        if self._json is None and HAS_JSON:
            try:
                self._json = json.loads(self.data)
            except ValueError:
                pass
        return self._json

    @property
    def yaml(self):
        """ The probe data as a decoded YAML data structure """
        if self._yaml is None and HAS_YAML:
            try:
                self._yaml = yaml.load(self.data)
            except yaml.YAMLError:
                pass
        return self._yaml


class ProbeSet(Bcfg2.Server.Plugin.EntrySet):
    """ Handle universal and group- and host-specific probe files """
    ignore = re.compile(r'^(\.#.*|.*~|\..*\.(tmp|sw[px])|probed\.xml)$')
    probename = \
        re.compile(r'(.*/)?(?P<basename>\S+?)(\.(?P<mode>(?:G\d\d)|H)_\S+)?$')
    bangline = re.compile(r'^#!\s*(?P<interpreter>.*)$')
    basename_is_regex = True

    def __init__(self, path, plugin_name):
        self.plugin_name = plugin_name
        Bcfg2.Server.Plugin.EntrySet.__init__(self, r'[0-9A-Za-z_\-]+', path,
                                              Bcfg2.Server.Plugin.SpecificData)
        Bcfg2.Server.FileMonitor.get_fam().AddMonitor(path, self)

    def HandleEvent(self, event):
        """ handle events on everything but probed.xml """
        if (event.filename != self.path and
            not event.filename.endswith("probed.xml")):
            return self.handle_event(event)

    def get_probe_data(self, metadata):
        """ Get an XML description of all probes for a client suitable
        for sending to that client.

        :param metadata: The client metadata to get probes for.
        :type metadata: Bcfg2.Server.Plugins.Metadata.ClientMetadata
        :returns: list of lxml.etree._Element objects, each of which
                  represents one probe.
        """
        ret = []
        build = dict()
        candidates = self.get_matching(metadata)
        candidates.sort(key=operator.attrgetter('specific'))
        for entry in candidates:
            rem = self.probename.match(entry.name)
            pname = rem.group('basename')
            if pname not in build:
                build[pname] = entry

        for (name, entry) in list(build.items()):
            probe = lxml.etree.Element('probe')
            probe.set('name', os.path.basename(name))
            probe.set('source', self.plugin_name)
            if (metadata.version_info and
                metadata.version_info > (1, 3, 1, '', 0)):
                try:
                    probe.text = entry.data.decode('utf-8')
                except AttributeError:
                    probe.text = entry.data
            else:
                try:
                    probe.text = entry.data
                except:  # pylint: disable=W0702
                    self.logger.error("Client unable to handle unicode "
                                      "probes. Skipping %s" %
                                      probe.get('name'))
                    continue
            match = self.bangline.match(entry.data.split('\n')[0])
            if match:
                probe.set('interpreter', match.group('interpreter'))
            else:
                probe.set('interpreter', '/bin/sh')
            ret.append(probe)
        return ret

    def __str__(self):
        return "ProbeSet for %s" % self.plugin_name


class Probes(Bcfg2.Server.Plugin.Probing,
             Bcfg2.Server.Plugin.Connector,
             Bcfg2.Server.Plugin.DatabaseBacked):
    """ A plugin to gather information from a client machine """
    __author__ = 'bcfg-dev@mcs.anl.gov'

    groupline_re = re.compile(r'^group:\s*(?P<groupname>\S+)\s*')

    options = [
        Bcfg2.Options.BooleanOption(
            cf=('probes', 'use_database'), dest="probes_db",
            help="Use database capabilities of the Probes plugin")]
    options_parsed_hook = staticmethod(load_django_models)

    def __init__(self, core, datastore):
        Bcfg2.Server.Plugin.Probing.__init__(self)
        Bcfg2.Server.Plugin.Connector.__init__(self)
        Bcfg2.Server.Plugin.DatabaseBacked.__init__(self, core, datastore)

        try:
            self.probes = ProbeSet(self.data, self.name)
        except:
            err = sys.exc_info()[1]
            raise Bcfg2.Server.Plugin.PluginInitError(err)

        if self._use_db:
            self.probestore = DBProbeStore(core, datastore)
        else:
            self.probestore = XMLProbeStore(core, datastore)

    @track_statistics()
    def GetProbes(self, metadata):
        return self.probes.get_probe_data(metadata)

    @track_statistics()
    def ReceiveData(self, client, datalist):
        cgroups = set()
        cdata = dict()
        for data in datalist:
            groups, cdata[data.get("name")] = \
                self.ReceiveDataItem(client, data)
            cgroups.update(groups)
        self.probestore.set_groups(client.hostname, list(cgroups))
        self.probestore.set_data(client.hostname, cdata)
        self.probestore.commit()

    def ReceiveDataItem(self, client, data):
        """ Receive probe results pertaining to client.  Returns a
        tuple of (<probe groups>, <probe data>). """
        if data.text is None:
            self.logger.info("Got null response to probe %s from %s" %
                             (data.get('name'), client.hostname))
            return [], ''
        dlines = data.text.split('\n')
        self.logger.debug("Processing probe from %s: %s:%s" %
                          (client.hostname, data.get('name'),
                           [line.strip() for line in dlines]))
        groups = []
        for line in dlines[:]:
            match = self.groupline_re.match(line)
            if match:
                groups.append(match.group("groupname"))
                dlines.remove(line)
        return (groups, ProbeData("\n".join(dlines)))

    def get_additional_groups(self, metadata):
        return self.probestore.get_groups(metadata.hostname)

    def get_additional_data(self, metadata):
        return self.probestore.get_data(metadata.hostname)