import functools

import win32api
import win32evtlog
import win32evtlogutil

error = win32api.error  # The error the evtlog module raises.


class EventLog(object):
    def __init__(self, name="Application", machine_name=None):
        self.machine_name = machine_name
        self.name = name
        self.formatter = functools.partial(
            win32evtlogutil.FormatMessage, logType=self.name
        )

    def __enter__(self):
        if hasattr(self, 'handle'):
            raise ValueError("Overlapping attempts to use this log context")
        self.handle = win32evtlog.OpenEventLog(self.machine_name, self.name)
        return self

    def __exit__(self, *args):
        win32evtlog.CloseEventLog(self.handle)
        del self.handle

    _default_flags = (
        win32evtlog.EVENTLOG_BACKWARDS_READ | win32evtlog.EVENTLOG_SEQUENTIAL_READ
    )

    def get_records(self, flags=_default_flags):
        with self:
            while True:
                objects = win32evtlog.ReadEventLog(self.handle, flags, 0)
                if not objects:
                    break
                for item in objects:
                    yield item

    def __iter__(self):
        return self.get_records()

    def format_record(self, record):
        return self.formatter(record)

    def format_records(self, records=None):
        if records is None:
            records = self.get_records()
        return map(self.format_record, records)