""" set group membership based on client hostnames """

import os
import re
import sys
import Bcfg2.Server.Lint
import Bcfg2.Server.Plugin
from Bcfg2.Utils import PackedDigitRange


class PatternInitializationError(Exception):
    """Raised when creating a PatternMap object fails."""


class PatternMap(object):
    """Handler for a single pattern or range."""

    def __init__(self, pattern, rangestr, groups):
        self.pattern = pattern
        self.rangestr = rangestr
        self.groups = groups
        try:
            if pattern is not None:
                self._re = re.compile(pattern)
                self.process = self.process_re
            elif rangestr is not None:
                if '\\' in rangestr:
                    raise PatternInitializationError(
                        "Backslashes are not allowed in NameRanges")
                range_finder = r'\[\[[\d\-,]+\]\]'
                self.process = self.process_range
                self._re = re.compile(r'^' + re.sub(range_finder, r'(\d+)',
                                                    rangestr))
                dmatcher = re.compile(re.sub(range_finder,
                                             r'\[\[([\d\-,]+)\]\]',
                                             rangestr))
                self.dranges = [PackedDigitRange(x)
                                for x in dmatcher.match(rangestr).groups()]
            else:
                raise PatternInitializationError("No pattern or range given")
        except re.error:
            raise PatternInitializationError(
                "Could not compile pattern regex: %s" % sys.exc_info()[1])

    def process_range(self, name):
        """match the given hostname against a range-based NameRange."""
        match = self._re.match(name)
        if not match:
            return None
        digits = match.groups()
        for grp in range(len(digits)):
            if not self.dranges[grp].includes(digits[grp]):
                return None
        return self.groups

    def process_re(self, name):
        """match the given hostname against a regex-based NamePattern."""
        match = self._re.search(name)
        if not match:
            return None
        ret = []
        sub = match.groups()
        for group in self.groups:
            newg = group
            for idx in range(len(sub)):
                newg = newg.replace('$%s' % (idx + 1), sub[idx])
            ret.append(newg)
        return ret

    def __str__(self):
        return "%s: %s %s" % (self.__class__.__name__, self.pattern,
                              self.groups)


class PatternFile(Bcfg2.Server.Plugin.XMLFileBacked):
    """representation of GroupPatterns config.xml."""
    __identifier__ = None
    create = 'GroupPatterns'

    def __init__(self, filename, core=None):
        Bcfg2.Server.Plugin.XMLFileBacked.__init__(self, filename,
                                                   should_monitor=True)
        self.core = core
        self.patterns = []

    def Index(self):
        Bcfg2.Server.Plugin.XMLFileBacked.Index(self)
        if (self.core and
                self.core.metadata_cache_mode in ['cautious', 'aggressive']):
            self.core.metadata_cache.expire()
        self.patterns = []
        for entry in self.xdata.xpath('//GroupPattern'):
            try:
                groups = [g.text for g in entry.findall('Group')]
                for pat_ent in entry.findall('NamePattern'):
                    pat = pat_ent.text
                    self.patterns.append(PatternMap(pat, None, groups))
                for range_ent in entry.findall('NameRange'):
                    rng = range_ent.text
                    self.patterns.append(PatternMap(None, rng, groups))
            except PatternInitializationError:
                self.logger.error("GroupPatterns: Failed to initialize "
                                  "pattern %s: %s" % (entry.text,
                                                      sys.exc_info()[1]))

    def process_patterns(self, hostname):
        """ return a list of groups that should be added to the given
        client based on patterns that match the hostname """
        ret = []
        for pattern in self.patterns:
            grps = pattern.process(hostname)
            if grps is not None:
                ret.extend(grps)
        return ret


class GroupPatterns(Bcfg2.Server.Plugin.Plugin,
                    Bcfg2.Server.Plugin.Connector):
    """set group membership based on client hostnames."""

    def __init__(self, core):
        Bcfg2.Server.Plugin.Plugin.__init__(self, core)
        Bcfg2.Server.Plugin.Connector.__init__(self)
        self.config = PatternFile(os.path.join(self.data, 'config.xml'),
                                  core=core)

    def get_additional_groups(self, metadata):
        return self.config.process_patterns(metadata.hostname)