from multiprocessing.process import current_process
from multiprocessing.queues import Queue

from django import db
from django.utils.translation import gettext_lazy as _

import django_q.tasks
from django_q.brokers import Broker, get_broker
from django_q.conf import Conf, logger, setproctitle
from django_q.models import Success, Task
from django_q.signals import post_execute
from django_q.signing import SignedPackage
from django_q.utils import close_old_django_connections, get_func_repr

try:
    import setproctitle
except ModuleNotFoundError:
    setproctitle = None


def monitor(result_queue: Queue, broker: Broker = None):
    """
    Gets finished tasks from the result queue and saves them to Django
    :type broker: brokers.Broker
    :type result_queue: multiprocessing.Queue
    """
    if not broker:
        broker = get_broker()
    proc_name = current_process().name
    if setproctitle:
        setproctitle.setproctitle(f"qcluster {proc_name} monitor")
    logger.info(
        _("%(name)s monitoring at %(id)s")
        % {"name": proc_name, "id": current_process().pid}
    )
    for task in iter(result_queue.get, "STOP"):
        # save the result
        if task.get("cached", False):
            save_cached(task, broker)
        else:
            save_task(task, broker)
        # acknowledge result
        ack_id = task.pop("ack_id", False)
        if ack_id and (task["success"] or task.get("ack_failure", False)):
            broker.acknowledge(ack_id)
        # signal execution done
        post_execute.send(sender="django_q", task=task)
        # log the result
        info_name = get_func_repr(task["func"])
        if task["success"]:
            # log success
            logger.info(
                _("Processed '%(info_name)s' (%(task_name)s)")
                % {"info_name": info_name, "task_name": task["name"]}
            )
        else:
            # log failure
            logger.error(
                _("Failed '%(info_name)s' (%(task_name)s) - %(task_result)s")
                % {
                    "info_name": info_name,
                    "task_name": task["name"],
                    "task_result": task["result"],
                }
            )
    logger.info(_("%(name)s stopped monitoring results") % {"name": proc_name})


def save_task(task, broker: Broker):
    """
    Saves the task package to Django or the cache
    :param task: the task package
    :type broker: brokers.Broker
    """
    # SAVE LIMIT < 0 : Don't save success
    if not task.get("save", Conf.SAVE_LIMIT >= 0) and task["success"]:
        return
    # enqueues next in a chain
    if task.get("chain", None):
        django_q.tasks.async_chain(
            task["chain"],
            group=task["group"],
            cached=task["cached"],
            sync=task["sync"],
            broker=broker,
        )
    # SAVE LIMIT > 0: Prune database, SAVE_LIMIT 0: No pruning
    close_old_django_connections()

    try:
        filters = {}
        if (
            Conf.SAVE_LIMIT_PER
            and Conf.SAVE_LIMIT_PER in {"group", "name", "func"}
            and Conf.SAVE_LIMIT_PER in task
        ):
            value = task[Conf.SAVE_LIMIT_PER]
            if Conf.SAVE_LIMIT_PER == "func":
                value = get_func_repr(value)
            filters[Conf.SAVE_LIMIT_PER] = value

        with db.transaction.atomic(using=db.router.db_for_write(Success)):
            last = Success.objects.filter(**filters).select_for_update().last()
            if (
                task["success"]
                and 0 < Conf.SAVE_LIMIT <= Success.objects.filter(**filters).count()
            ):
                last.delete()

        # check if this task has previous results
        try:
            existing_task = Task.objects.get(id=task["id"], name=task["name"])
            # only update the result if it hasn't succeeded yet
            if not existing_task.success:
                existing_task.stopped = task["stopped"]
                existing_task.result = task["result"]
                existing_task.success = task["success"]
                existing_task.attempt_count = existing_task.attempt_count + 1
                existing_task.save()

            if (
                Conf.MAX_ATTEMPTS > 0
                and existing_task.attempt_count >= Conf.MAX_ATTEMPTS
            ):
                broker.acknowledge(task["ack_id"])

        except Task.DoesNotExist:
            # convert func to string
            func = get_func_repr(task["func"])
            Task.objects.create(
                id=task["id"],
                name=task["name"],
                func=func,
                hook=task.get("hook"),
                args=task["args"],
                kwargs=task["kwargs"],
                cluster=task.get("cluster"),
                started=task["started"],
                stopped=task["stopped"],
                result=task["result"],
                group=task.get("group"),
                success=task["success"],
                attempt_count=1,
            )
    except Exception:
        logger.exception("Could not save task result")


def save_cached(task, broker: Broker):
    task_key = f'{broker.list_key}:{task["id"]}'
    timeout = task["cached"]
    if timeout is True:
        timeout = None
    try:
        group = task.get("group", None)
        iter_count = task.get("iter_count", 0)
        # if it's a group append to the group list
        if group:
            group_key = f"{broker.list_key}:{group}:keys"
            group_list = broker.cache.get(group_key) or []
            # if it's an iter group, check if we are ready
            if iter_count and len(group_list) == iter_count - 1:
                group_args = f"{broker.list_key}:{group}:args"
                # collate the results into a Task result
                results = [
                    SignedPackage.loads(broker.cache.get(k))["result"]
                    for k in group_list
                ]
                results.append(task["result"])
                task["result"] = results
                task["id"] = group
                task["args"] = SignedPackage.loads(broker.cache.get(group_args))
                task.pop("iter_count", None)
                task.pop("group", None)
                if task.get("iter_cached", None):
                    task["cached"] = task.pop("iter_cached", None)
                    save_cached(task, broker=broker)
                else:
                    save_task(task, broker)
                broker.cache.delete_many(group_list)
                broker.cache.delete_many([group_key, group_args])
                return
            # save the group list
            group_list.append(task_key)
            broker.cache.set(group_key, group_list, timeout)
            # async_task next in a chain
            if task.get("chain", None):
                django_q.tasks.async_chain(
                    task["chain"],
                    group=group,
                    cached=task["cached"],
                    sync=task["sync"],
                    broker=broker,
                )
        # save the task
        broker.cache.set(task_key, SignedPackage.dumps(task), timeout)
    except Exception:
        logger.exception("Could not save task result")