"""This module defines a parser for syslog."""

from aminer.parsing.DateTimeModelElement import DateTimeModelElement
from aminer.parsing.FixedDataModelElement import FixedDataModelElement
from aminer.parsing.SequenceModelElement import SequenceModelElement
from aminer.parsing.VariableByteDataModelElement import VariableByteDataModelElement


def get_model(time_model=None):
    """Return the model for parsing a standard syslog preamble including
    timestamp and hostname.

    @param time_model when not none, the given model element is used for parsing timestamps. Otherwise a standard DateTimeModelElement
    with format b"%b %d %H:%M:%S" is created. CAVEAT: the standard model may not work when log data timestamp locale does not match
    host or shell environment locale. See MultiLocaleDatetime_modelElement instead.
    """
    if time_model is None:
        time_model = DateTimeModelElement("time", b"%b %d %H:%M:%S", start_year=2020)
    host_name_model = VariableByteDataModelElement("host", b"-.01234567890abcdefghijklmnopqrstuvwxyz")
    model = SequenceModelElement("syslog", [
        time_model,
        FixedDataModelElement("sp0", b" "),
        host_name_model,
        FixedDataModelElement("sp1", b" ")
    ])
    return model
