terom@2: import logging; log = logging.getLogger('pvl.syslog.filter')
terom@2: 
terom@2: import re # XXX
terom@2: import os.path, fnmatch
terom@2: 
terom@2: class SyslogFilter (object) :
terom@2:     """
terom@2:         Match syslog messages fields against given patterns.
terom@2:     """
terom@2:     
terom@2:     @classmethod
terom@2:     def build (cls, **filters) :
terom@2:         """
terom@2:             Match using given non-None fields.
terom@2:         """
terom@2: 
terom@2:         # drop None's
terom@2:         return cls(dict((attr, regex) for attr, regex in filters.iteritems() if regex is not None))
terom@2: 
terom@2:     def __init__ (self, filters) :
terom@2:         """
terom@2:             Match using given { field: regex }.
terom@2:         """
terom@2: 
terom@2:         self.filters = filters
terom@2: 
terom@2:     def match_glob (self, attr, glob, value=None) :
terom@2:         """
terom@2:             Match prog as glob.
terom@2:         """
terom@2:         
terom@2:         if not glob :
terom@2:             return { attr: value }
terom@2: 
terom@2:         if not value :
terom@2:             # require
terom@2:             return False
terom@2: 
terom@2:         # normalize
terom@2:         value = value.strip()
terom@2: 
terom@2:         # match
terom@2:         if fnmatch.fnmatch(value, glob) :
terom@2:             return { attr: value }
terom@2:         else :
terom@2:             return False
terom@2:  
terom@2:     match_facility = match_glob
terom@2: 
terom@2:     def match_prog (self, attr, glob, prog=None) :
terom@2:         """
terom@2:             Match prog as glob.
terom@2:         """
terom@2: 
terom@2:         if prog :
terom@2:             # normalize
terom@2:             prog = prog.strip().lower()
terom@2:     
terom@2:             if prog.startswith('/') :
terom@2:                 # leaves postfix/* intact, but fixes /usr/bin/cron
terom@2:                 _, prog = os.path.split(prog)
terom@2: 
terom@2:         # match
terom@2:         return self.match_glob(attr, glob, prog)
terom@2: 
terom@2:     REGEX_TYPE = type(re.compile(''))
terom@2: 
terom@2:     def match_regex (self, attr, regex, value=None) :
terom@2:         """
terom@2:             Match given value against given pattern.
terom@2:         """
terom@2: 
terom@2:         if not regex :
terom@2:             return { attr: value }
terom@2: 
terom@2:         if not value :
terom@2:             # XXX: optional = match empty string?
terom@2:             value = ''
terom@2:         else :
terom@2:             # normalize; XXX: unicode?
terom@2:             value = str(value).strip()
terom@2:         
terom@2:         # match
terom@2:         match = regex.match(value)
terom@2: 
terom@2:         if not match :
terom@2:             return False
terom@2: 
terom@2:         # as match-values
terom@2:         matches = { attr: match.group(0) } # whole match
terom@2:         matches.update(match.groupdict())
terom@2: 
terom@2:         # TODO match.expand?
terom@2: 
terom@2:         return matches
terom@2: 
terom@2:     def filter (self, item) :
terom@2:         """
terom@2:             Match given item. Returns any matched values (including regexp capture groups) across all fields.
terom@2:         """
terom@2: 
terom@2:         match = None
terom@2:         matches = {}
terom@2: 
terom@2:         for attr in self.filters :
terom@2:             # filter
terom@2:             filter = self.filters[attr]
terom@2: 
terom@2:             # lookup match-func
terom@2:             match = getattr(self, 'match_{attr}'.format(attr=attr), None)
terom@2: 
terom@2:             if match :
terom@2:                 pass
terom@2: 
terom@2:             elif isinstance(filter, self.REGEX_TYPE) :
terom@2:                 match = self.match_regex
terom@2: 
terom@2:             else :
terom@2:                 match = self.match_glob
terom@2: 
terom@2:             # apply match
terom@2:             if attr in item :
terom@2:                 match = match(attr, filter, item[attr])
terom@2:             else :
terom@2:                 match = match(attr, filter)
terom@2: 
terom@2:             log.debug("%s: %s", attr, match)
terom@2: 
terom@2:             if match :
terom@2:                 # match
terom@2:                 matches.update(match)
terom@2:             
terom@2:             else :
terom@2:                 # reject
terom@2:                 return
terom@2:         
terom@2:         # test last match
terom@2:         if match is None :
terom@2:             # empty filter -> all None
terom@2:             return True
terom@2:         else :
terom@2:             return matches
terom@2: 
terom@2:     def process (self, items) :
terom@2:         for item in items:
terom@2:             match = self.filter(item)
terom@2: 
terom@2:             if match :
terom@2:                 yield item
terom@2:     
terom@2:     __call__ = process
terom@2: 
terom@2:     def __nonzero__ (self) :
terom@2:         return bool(self.filters)
terom@2: 
terom@2:     def __repr__ (self) :
terom@2:         return repr(self.filters)