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"""

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    Miscellaneous things

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"""

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import datetime, calendar, pytz

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import os, errno

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from qmsk.web.urltree import URLType

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class URLChannelName (URLType) :

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    """

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        Handle LogChannel names in URLs. Deals with instances of LogChannel

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    """

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    def __init__ (self, channels) :

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        """

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            Use the given { name -> LogChannel } dict

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        """

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        self.channels = channels

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    def parse (self, chan_name) :

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        """

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            chan_name -> LogChannel

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        """

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        return self.channels[chan_name]

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    def build (self, chan) :

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        """

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            LogChannel -> chan_name

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        """

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        return chan.id

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class URLDateType (URLType) :

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    """

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        Handle dates in URLs as shortened UTC datetime timestamps

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    """

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    # percision = hour

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    SCALE = 60 * 60

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    def __init__ (self, date_fmt) :

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        """

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            Format/parse dates using the given format

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        """

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        self.date_fmt = date_fmt

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    def parse (self, sts_str) :

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        """

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            short_timestamp_str -> datetime.datetime

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        """

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        # scale -> from_utc + return

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        return from_utc_timestamp(int(sts_str) * self.SCALE)

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    def build (self, dtz) :

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        """

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            datetime.datetime -> short_timestamp_str

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        """

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        # force it to be interpreted as UTC

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        dt_utc = dtz.replace(tzinfo=pytz.utc)

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        # scale the UTC timestamp

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        sts = to_utc_timestamp(dt_utc) / self.SCALE

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        # str

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        return str(sts)

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class URLTimestampType (URLType) :

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    """

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        Handles an integer UNIX timestamp as an UTC datetime

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    """

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    def parse (self, timestamp_str) :

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        """

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            timestamp_str -> pytz.utc datetime.datetime

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        """

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        return from_utc_timestamp(int(timestamp_str))

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    def build (self, dtz) :

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        """

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            pytz.utc datetime.datetime -> timestamp_str

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        """

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        return str(to_utc_timestamp(dtz))

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def from_utc_timestamp (timestamp) :

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    """

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        Converts a UNIX timestamp into a datetime.datetime

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    """

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    return datetime.datetime.utcfromtimestamp(timestamp).replace(tzinfo=pytz.utc)

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def to_utc_timestamp (dt) :

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    """

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        Converts a datetime.datetime into a UNIX timestamp

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    """

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    return calendar.timegm(dt.utctimetuple())

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def mtime (path, ignore_missing=False) :

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    """

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        Gets the mtime for the given path as an UTC datetime, or None, if the file doesn't exist and ignore_missing

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    """

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    try :

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        # stat

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        st = os.stat(path)

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    # trap IOError

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    except os.error, e :

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        # ENOENT?

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        if ignore_missing and e.errno == errno.ENOENT :

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            return None

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        else :

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            raise

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    else :

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        # decode

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        return from_utc_timestamp(st.st_mtime)

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