from __future__ import absolute_import

from typing import Callable
from typing import Optional


class uWSGIConfigError(Exception):
    """uWSGI configuration error.

    This is raised when uwsgi configuration is incompatible with the library.
    """


class uWSGIConfigDeprecationWarning(DeprecationWarning):
    """uWSGI configuration deprecation warning.

    This is raised when uwsgi configuration is incompatible with the library,
    and future versions of the library plans to raise an error and stop
    supporting the configuration.
    """


class uWSGIMasterProcess(Exception):
    """The process is uWSGI master process."""


def should_register_atexit() -> bool:
    """Check if Python atexit handlers should be registered under uwsgi.

    Returns False if running under uwsgi with --skip-atexit, True otherwise.
    This respects the user's explicit request to skip atexit handlers, which
    is important because running complex operations (like HTTP uploads) during
    atexit can cause heap corruption during process shutdown.
    """
    try:
        import uwsgi

        return not uwsgi.opt.get("skip-atexit")
    except (ImportError, AttributeError):
        # Not running under uwsgi or uwsgi.opt not available
        return True


def check_uwsgi(worker_callback: Optional[Callable] = None, atexit: Optional[Callable] = None) -> None:
    """Check whetever uwsgi is running and what needs to be done.

    :param worker_callback: Callback function to call in uWSGI worker processes.
    """
    try:
        import uwsgi
    except ImportError:
        return

    if not hasattr(uwsgi, "opt"):
        msg = "Unable to access uwsgi options. Please make sure that the --import=ddtrace.auto option is set"
        raise uWSGIConfigError(msg)

    if not (uwsgi.opt.get("enable-threads") or int(uwsgi.opt.get("threads") or 0)):
        msg = "enable-threads option must be set to true, or a positive number of threads must be set"
        raise uWSGIConfigError(msg)

    if (
        hasattr(uwsgi, "version_info")
        and uwsgi.version_info < (2, 0, 30)
        and (uwsgi.opt.get("lazy-apps") or uwsgi.opt.get("lazy"))
        and not uwsgi.opt.get("skip-atexit")
    ):
        msg = "skip-atexit option must be set when lazy-apps or lazy is set for \
            uwsgi<2.0.30, see https://github.com/unbit/uwsgi/pull/2726. We plan \
            to raise an error in ddtrace 4.x release."
        raise uWSGIConfigDeprecationWarning(msg)

    # If uwsgi has more than one process, it is running in prefork operational mode: uwsgi is going to fork multiple
    # sub-processes.
    # If lazy-app is enabled, then the app is loaded in each subprocess independently. This is fine.
    # If it's not enabled, then the app will be loaded in the master process, and uwsgi will `fork()` abruptly,
    # bypassing Python sanity checks. We need to handle this case properly.
    # The proper way to handle that is to allow to register a callback function to run in the subprocess at their
    # startup, and warn the caller that this is the master process and that (probably) nothing should be done.
    if uwsgi.numproc > 1 and not uwsgi.opt.get("lazy-apps") and uwsgi.worker_id() == 0:
        if not uwsgi.opt.get("master"):
            # Having multiple workers without the master process is not supported:
            # the postfork hooks are not available, so there's no way to start a different profiler in each
            # worker
            raise uWSGIConfigError("master option must be enabled when multiple processes are used")

        # Register the function to be called in child process at startup
        if worker_callback is not None:
            try:
                import uwsgidecorators
            except ImportError:
                raise uWSGIConfigError("Running under uwsgi but uwsgidecorators cannot be imported")
            uwsgidecorators.postfork(worker_callback)

        if atexit is not None:
            original_atexit = getattr(uwsgi, "atexit", None)

            def _atexit():
                try:
                    atexit()
                except Exception:
                    pass

                if original_atexit is not None:
                    original_atexit()

            uwsgi.atexit = _atexit

        raise uWSGIMasterProcess()