#!/usr/bin/env python3

import functools
import importlib
import logging
import os
import sys
from inspect import stack
from typing import List

import config
import logging_utils
from argparse_utils import ActionNoYes

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


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.',
)
args.add_argument(
    '--dump_all_objects',
    action=ActionNoYes,
    default=False,
    help='Should we dump the Python import tree before main?',
)
args.add_argument(
    '--audit_import_events',
    action=ActionNoYes,
    default=False,
    help='Should we audit all import events?',
)
args.add_argument(
    '--run_profiler',
    action=ActionNoYes,
    default=False,
    help='Should we run cProfile on this code?',
)
args.add_argument(
    '--trace_memory',
    action=ActionNoYes,
    default=False,
    help='Should we record/report on memory utilization?',
)

original_hook = sys.excepthook


def handle_uncaught_exception(exc_type, exc_value, exc_tb):
    """
    Top-level exception handler for exceptions that make it past any exception
    handlers in the python code being run.  Logs the error and stacktrace then
    maybe attaches a debugger.

    """
    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, maybe debug.
            import traceback

            traceback.print_exception(exc_type, exc_value, exc_tb)
            if config.config['debug_unhandled_exceptions']:
                import pdb

                logger.info("Invoking the debugger...")
                pdb.pm()
            else:
                original_hook(exc_type, exc_value, exc_tb)


class ImportInterceptor(importlib.abc.MetaPathFinder):
    def __init__(self):
        import collect.trie

        self.module_by_filename_cache = {}
        self.repopulate_modules_by_filename()
        self.tree = collect.trie.Trie()
        self.tree_node_by_module = {}

    def repopulate_modules_by_filename(self):
        self.module_by_filename_cache.clear()
        for mod in sys.modules:
            if hasattr(sys.modules[mod], '__file__'):
                fname = getattr(sys.modules[mod], '__file__')
            else:
                fname = 'unknown'
            self.module_by_filename_cache[fname] = mod

    def should_ignore_filename(self, filename: str) -> bool:
        return 'importlib' in filename or 'six.py' in filename

    def find_module(self, fullname, path):
        raise Exception(
            "This method has been deprecated since Python 3.4, please upgrade."
        )

    def find_spec(self, loaded_module, path=None, target=None):
        s = stack()
        for x in range(3, len(s)):
            filename = s[x].filename
            if self.should_ignore_filename(filename):
                continue

            loading_function = s[x].function
            if filename in self.module_by_filename_cache:
                loading_module = self.module_by_filename_cache[filename]
            else:
                self.repopulate_modules_by_filename()
                loading_module = self.module_by_filename_cache.get(filename, 'unknown')

            path = self.tree_node_by_module.get(loading_module, [])
            path.extend([loaded_module])
            self.tree.insert(path)
            self.tree_node_by_module[loading_module] = path

            msg = f'*** Import {loaded_module} from {filename}:{s[x].lineno} in {loading_module}::{loading_function}'
            logger.debug(msg)
            print(msg)
            return
        msg = f'*** Import {loaded_module} from ?????'
        logger.debug(msg)
        print(msg)

    def invalidate_caches(self):
        pass

    def find_importer(self, module: str):
        if module in self.tree_node_by_module:
            node = self.tree_node_by_module[module]
            return node
        return []


# Audit import events?  Note: this runs early in the lifetime of the
# process (assuming that import bootstrap happens early); config has
# (probably) not yet been loaded or parsed the commandline.  Also,
# some things have probably already been imported while we weren't
# watching so this information may be incomplete.
#
# Also note: move bootstrap up in the global import list to catch
# more import events and have a more complete record.
import_interceptor = None
for arg in sys.argv:
    if arg == '--audit_import_events':
        import_interceptor = ImportInterceptor()
        sys.meta_path.insert(0, import_interceptor)


def dump_all_objects() -> None:
    global import_interceptor
    messages = {}
    all_modules = sys.modules
    for obj in object.__subclasses__():
        if not hasattr(obj, '__name__'):
            continue
        klass = obj.__name__
        if not hasattr(obj, '__module__'):
            continue
        class_mod_name = obj.__module__
        if class_mod_name in all_modules:
            mod = all_modules[class_mod_name]
            if not hasattr(mod, '__name__'):
                mod_name = class_mod_name
            else:
                mod_name = mod.__name__
            if hasattr(mod, '__file__'):
                mod_file = mod.__file__
            else:
                mod_file = 'unknown'
            if import_interceptor is not None:
                import_path = import_interceptor.find_importer(mod_name)
            else:
                import_path = 'unknown'
            msg = f'{class_mod_name}::{klass} ({mod_file})'
            if import_path != 'unknown' and len(import_path) > 0:
                msg += f' imported by {import_path}'
            messages[f'{class_mod_name}::{klass}'] = msg
    for x in sorted(messages.keys()):
        logger.debug(messages[x])
        print(messages[x])


def initialize(entry_point):
    """
    Remember to initialize config, initialize logging, set/log a random
    seed, etc... before running main.

    """

    @functools.wraps(entry_point)
    def initialize_wrapper(*args, **kwargs):
        # Hook top level unhandled exceptions, maybe invoke debugger.
        if sys.excepthook == sys.__excepthook__:
            sys.excepthook = handle_uncaught_exception

        # Try to figure out the name of the program entry point.  Then
        # parse configuration (based on cmdline flags, environment vars
        # etc...)
        if (
            '__globals__' in entry_point.__dict__
            and '__file__' in entry_point.__globals__
        ):
            config.parse(entry_point.__globals__['__file__'])
        else:
            config.parse(None)

        if config.config['trace_memory']:
            import tracemalloc

            tracemalloc.start()

        # Initialize logging... and log some remembered messages from
        # config module.
        logging_utils.initialize_logging(logging.getLogger())
        config.late_logging()

        # Maybe log some info about the python interpreter itself.
        logger.debug(
            f'Platform: {sys.platform}, maxint=0x{sys.maxsize:x}, byteorder={sys.byteorder}'
        )
        logger.debug(f'Python interpreter version: {sys.version}')
        logger.debug(f'Python implementation: {sys.implementation}')
        logger.debug(f'Python C API version: {sys.api_version}')
        logger.debug(f'Python path: {sys.path}')

        # 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}'
            logger.debug(msg)
            print(msg)
        random.seed(random_seed)

        # Do it, invoke the user's code.  Pay attention to how long it takes.
        logger.debug(f'Starting {entry_point.__name__} (program entry point)')
        ret = None
        import stopwatch

        if config.config['run_profiler']:
            import cProfile
            from pstats import SortKey

            with stopwatch.Timer() as t:
                cProfile.runctx(
                    "ret = entry_point(*args, **kwargs)",
                    globals(),
                    locals(),
                    None,
                    SortKey.CUMULATIVE,
                )
        else:
            with stopwatch.Timer() as t:
                ret = entry_point(*args, **kwargs)

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

        if config.config['trace_memory']:
            snapshot = tracemalloc.take_snapshot()
            top_stats = snapshot.statistics('lineno')
            print()
            print("--trace_memory's top 10 memory using files:")
            for stat in top_stats[:10]:
                print(stat)

        if config.config['dump_all_objects']:
            dump_all_objects()

        if config.config['audit_import_events']:
            global import_interceptor
            if import_interceptor is not None:
                print(import_interceptor.tree)

        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 it doesn't return cleanly, call attention to the return value.
        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