import logging
from datetime import datetime
from typing import Callable, Optional
from uuid import uuid4

from celery import shared_task
from celery.utils.functional import LRUCache

from epdb.logic import SPathway
from epdb.models import EPModel, JobLog, Node, Package, Pathway, Setting, User

logger = logging.getLogger(__name__)
ML_CACHE = LRUCache(3)  # Cache the three most recent ML models to reduce load times.


def get_ml_model(model_pk: int):
    if model_pk not in ML_CACHE:
        ML_CACHE[model_pk] = EPModel.objects.get(id=model_pk)
    return ML_CACHE[model_pk]


def dispatch_eager(user: "User", job: Callable, *args, **kwargs):
    try:
        x = job(*args, **kwargs)
        log = JobLog()
        log.user = user
        log.task_id = uuid4()
        log.job_name = job.__name__
        log.status = "SUCCESS"
        log.done_at = datetime.now()
        log.task_result = str(x) if x else None
        log.save()

        return x
    except Exception as e:
        logger.exception(e)
        raise e


def dispatch(user: "User", job: Callable, *args, **kwargs):
    try:
        x = job.delay(*args, **kwargs)
        log = JobLog()
        log.user = user
        log.task_id = x.task_id
        log.job_name = job.__name__
        log.status = "INITIAL"
        log.save()

        return x.result
    except Exception as e:
        logger.exception(e)
        raise e


@shared_task(queue="background")
def mul(a, b):
    return a * b


@shared_task(queue="predict")
def predict_simple(model_pk: int, smiles: str):
    mod = get_ml_model(model_pk)
    res = mod.predict(smiles)
    return res


@shared_task(queue="background")
def send_registration_mail(user_pk: int):
    pass


@shared_task(bind=True, queue="model")
def build_model(self, model_pk: int):
    mod = EPModel.objects.get(id=model_pk)

    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="RUNNING", task_result=mod.url)

    try:
        mod.build_dataset()
        mod.build_model()
    except Exception as e:
        if JobLog.objects.filter(task_id=self.request.id).exists():
            JobLog.objects.filter(task_id=self.request.id).update(
                status="FAILED", task_result=mod.url
            )

        raise e

    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="SUCCESS", task_result=mod.url)

    return mod.url


@shared_task(bind=True, queue="model")
def evaluate_model(self, model_pk: int, multigen: bool, package_pks: Optional[list] = None):
    packages = None

    if package_pks:
        packages = Package.objects.filter(pk__in=package_pks)

    mod = EPModel.objects.get(id=model_pk)
    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="RUNNING", task_result=mod.url)

    try:
        mod.evaluate_model(multigen, eval_packages=packages)
    except Exception as e:
        if JobLog.objects.filter(task_id=self.request.id).exists():
            JobLog.objects.filter(task_id=self.request.id).update(
                status="FAILED", task_result=mod.url
            )

        raise e

    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="SUCCESS", task_result=mod.url)

    return mod.url


@shared_task(queue="model")
def retrain(model_pk: int):
    mod = EPModel.objects.get(id=model_pk)
    mod.retrain()


@shared_task(bind=True, queue="predict")
def predict(
    self,
    pw_pk: int,
    pred_setting_pk: int,
    limit: Optional[int] = None,
    node_pk: Optional[int] = None,
) -> Pathway:
    pw = Pathway.objects.get(id=pw_pk)
    setting = Setting.objects.get(id=pred_setting_pk)
    # If the setting has a model add/restore it from the cache
    if setting.model is not None:
        setting.model = get_ml_model(setting.model.pk)

    pw.kv.update(**{"status": "running"})
    pw.save()

    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="RUNNING", task_result=pw.url)

    try:
        # regular prediction
        if limit is not None:
            spw = SPathway(prediction_setting=setting, persist=pw)
            level = 0
            while not spw.done:
                spw.predict_step(from_depth=level)
                level += 1

                # break in case we are in incremental mode
                if limit != -1:
                    if level >= limit:
                        break

        elif node_pk is not None:
            n = Node.objects.get(id=node_pk, pathway=pw)
            spw = SPathway.from_pathway(pw)
            spw.predict_step(from_node=n)
        else:
            raise ValueError("Neither limit nor node_pk given!")

    except Exception as e:
        pw.kv.update({"status": "failed"})
        pw.save()

        if JobLog.objects.filter(task_id=self.request.id).exists():
            JobLog.objects.filter(task_id=self.request.id).update(
                status="FAILED", task_result=pw.url
            )

        raise e

    pw.kv.update(**{"status": "completed"})
    pw.save()

    if JobLog.objects.filter(task_id=self.request.id).exists():
        JobLog.objects.filter(task_id=self.request.id).update(status="SUCCESS", task_result=pw.url)

    return pw.url