"""
    Full-text searching of logs
"""

import datetime, calendar, pytz

import HyperEstraier as hype

import log_line

class LogSearchError (Exception) :
    """
        General search error
    """

    pass

class NoResultsFound (LogSearchError) :
    """
        No results found
    """

    pass

class LogSearchIndex (object) :
    """
        An index on the logs for a group of channels.

        This uses Hyper Estraier to handle searching, whereby each log line is a document (yes, I have a powerful server).

        These log documents have the following attributes:
            @uri        - channel/date/line
            @channel    - channel id
            @type       - the LogType id
            @timestamp  - UTC timestamp
            @source     - nickname

        Each document then has a single line of data, which is the log message itself
    """

    def __init__ (self, path, mode='r') :
        """
            Open the database, with the given mode:
                r       - read-only
                w       - read-write, create if not exists
                a       - read-write, do not create
                *       - read-write, truncate and create new
        """
        
        # mapping of { mode -> flags }
        mode_to_flag = {
            'r':    hype.Database.DBREADER,
            'w':    hype.Database.DBWRITER | hype.Database.DBCREAT,
            'a':    hype.Database.DBWRITER,
            '*':    hype.Database.DBWRITER | hype.Database.DBCREAT | hype.Database.DBTRUNC,
        }

        # look up flags
        flags = mode_to_flag[mode]
        
        # make instance
        self.db = hype.Database()
        
        # open
        if not self.db.open(path, flags) :
            raise Exception("Index open failed: %s, mode=%s, flags=%#06x: %s" % (path, mode, flags, self.db.err_msg(self.db.error())))

    def insert (self, channel, lines) :
        """
            Adds a sequence of LogLines from the given LogChannel to the index, and return the number of added items
        """
        
        # validate the LogChannel
        assert channel.name

        count = 0
        
        # iterate
        for line in lines :
            # validate the LogLine
            assert line.offset
            assert line.timestamp

            # create new document
            doc = hype.Document()

            # line date
            date = line.timestamp.date()

            # convert to UTC timestamp
            utc_timestamp = calendar.timegm(line.timestamp.utctimetuple())

            # ensure that it's not 1900
            assert date.year != 1900

            # add URI
            doc.add_attr('@uri',        "%s/%s/%d" % (channel.id, date.strftime('%Y-%m-%d'), line.offset))

            # add channel id
            doc.add_attr('@channel',    channel.id)

            # add type
            doc.add_attr('@type',       str(line.type))

            # add UTC timestamp
            doc.add_attr('@timestamp',  str(utc_timestamp))

            # add source attribute?
            if line.source :
                doc.add_attr('@source', str(line.source))
            
            # add data text
            doc.add_text(line.data.encode('utf8'))

            # put
            # XXX: what does this flag mean?
            if not self.db.put_doc(doc, hype.Database.PDCLEAN) :
                raise Exeception("Index put_doc failed")
            
            # count
            count += 1
        
        # return
        return count

    def search_cond (self, cond) :
        """
            Search using a raw hype.Condition. Raises NoResultsFound if there aren't any results
        """

        # execute search, unused 'flags' arg stays zero
        results = self.db.search(cond, 0)

        # no results?
        if not results :
            raise NoResultsFound()

        # iterate over the document IDs
        for doc_id in results :
            # load document, this throws an exception...
            # option constants are hype.Database.GDNOATTR/GDNOTEXT
            doc = self.db.get_doc(doc_id, 0)

            # load the attributes/text
            channel_id  = doc.attr('@channel')
            type        = int(doc.attr('@type'))
            timestamp   = datetime.datetime.fromtimestamp(int(doc.attr('@timestamp')), pytz.utc)
            source      = doc.attr('@source')
            data        = doc.cat_texts().decode('utf8')

            # build+yield to as LogLine
            # XXX: ignore channel_id for now
            yield log_line.LogLine(None, type, timestamp, source, data)
    
    def search (self, options=None, channel=None, phrase=None, order=None, max=None, skip=None) :
        """
            Search with flexible parameters

                options     - bitmask of hype.Condition.*
                channel     - LogChannel object
                phrase      - the search query phrase
                order       - order attribute expression
                max         - number of results to return
                skip        - number of results to skip
        """

        # build condition
        cond = hype.Condition()
        
        if options :
            # set options
            cond.set_options(options)
        
        if channel :
            # add channel attribute
            cond.add_attr("@channel STREQ %s" % (channel.id, ))
        
        if phrase :
            # add phrase
            cond.set_phrase(phrase)
        
        if order :
            # set order
            cond.set_order(order)
        
        if max :
            # set max
            cond.set_max(max)

        if skip :
            # set skip
            cond.set_skip(skip)

        # execute
        return self.search_cond(cond)

    def search_simple (self, channel, query, count=None, offset=None) :
        """
            Search for lines from the given channel for the given simple query
        """
        
        # use search(), backwards
        results = list(self.search(
            # simplified phrase
            options     = hype.Condition.SIMPLE,

            # specific channel
            channel     = channel,

            # given phrase
            phrase      = query,

            # order by timestamp
            order       = "@timestamp NUMD",

            # count/offset
            max         = count,
            skip        = offset,
        ))
        
        # reverse
        return reversed(results)