#!/usr/bin/env python3

import functools
import logging
import os
import sys

# This module is commonly used by others in here and should avoid
# taking any unnecessary dependencies back on them.

from argparse_utils import ActionNoYes
import config
import logging_utils

logger = logging.getLogger(__name__)

args = config.add_commandline_args(
    f'Bootstrap ({__file__})',
    'Args related to python program bootstrapper and Swiss army knife')
args.add_argument(
    '--debug_unhandled_exceptions',
    action=ActionNoYes,
    default=False,
    help='Break into pdb on top level unhandled exceptions.'
)
args.add_argument(
    '--show_random_seed',
    action=ActionNoYes,
    default=False,
    help='Should we display (and log.debug) the global random seed?'
)
args.add_argument(
    '--set_random_seed',
    type=int,
    nargs=1,
    default=None,
    metavar='SEED_INT',
    help='Override the global random seed with a particular number.'
)

original_hook = sys.excepthook


def handle_uncaught_exception(exc_type, exc_value, exc_tb):
    global original_hook
    msg = f'Unhandled top level exception {exc_type}'
    logger.exception(msg)
    print(msg, file=sys.stderr)
    if issubclass(exc_type, KeyboardInterrupt):
        sys.__excepthook__(exc_type, exc_value, exc_tb)
        return
    else:
        if (
                not sys.stderr.isatty() or
                not sys.stdin.isatty()
        ):
            # stdin or stderr is redirected, just do the normal thing
            original_hook(exc_type, exc_value, exc_tb)
        else:
            # a terminal is attached and stderr is not redirected, debug.
            if config.config['debug_unhandled_exceptions']:
                import traceback
                import pdb
                traceback.print_exception(exc_type, exc_value, exc_tb)
                logger.info("Invoking the debugger...")
                pdb.pm()
            else:
                original_hook(exc_type, exc_value, exc_tb)


def initialize(entry_point):

    """Remember to initialize config and logging before running main."""
    @functools.wraps(entry_point)
    def initialize_wrapper(*args, **kwargs):
        if sys.excepthook == sys.__excepthook__:
            sys.excepthook = handle_uncaught_exception
        if (
                '__globals__' in entry_point.__dict__ and
                '__file__' in entry_point.__globals__
        ):
            config.parse(entry_point.__globals__['__file__'])
        else:
            config.parse(None)

        logging_utils.initialize_logging(logging.getLogger())

        config.late_logging()

        # Allow programs that don't bother to override the random seed
        # to be replayed via the commandline.
        import random
        random_seed = config.config['set_random_seed']
        if random_seed is not None:
            random_seed = random_seed[0]
        else:
            random_seed = int.from_bytes(os.urandom(4), 'little')

        if config.config['show_random_seed']:
            msg = f'Global random seed is: {random_seed}'
            print(msg)
            logger.debug(msg)
        random.seed(random_seed)

        logger.debug(f'Starting {entry_point.__name__} (program entry point)')

        ret = None
        import stopwatch
        with stopwatch.Timer() as t:
            ret = entry_point(*args, **kwargs)
        logger.debug(
            f'{entry_point.__name__} (program entry point) returned {ret}.'
        )

        walltime = t()
        (utime, stime, cutime, cstime, elapsed_time) = os.times()
        logger.debug('\n'
                     f'user: {utime}s\n'
                     f'system: {stime}s\n'
                     f'child user: {cutime}s\n'
                     f'child system: {cstime}s\n'
                     f'machine uptime: {elapsed_time}s\n'
                     f'walltime: {walltime}s')
        if ret is not None and ret != 0:
            logger.error(f'Exit {ret}')
        else:
            logger.debug(f'Exit {ret}')
        sys.exit(ret)
    return initialize_wrapper