import json
import traceback
from contextvars import copy_context
import asyncio
from functools import partial

from _plotly_utils.utils import PlotlyJSONEncoder

from dash._callback_context import context_value
from dash._utils import AttributeDict
from dash.exceptions import PreventUpdate
from dash.background_callback._proxy_set_props import ProxySetProps
from dash.background_callback.managers import BaseBackgroundCallbackManager


class CeleryManager(BaseBackgroundCallbackManager):
    """Manage background execution of callbacks with a celery queue."""

    def __init__(self, celery_app, cache_by=None, expire=None):
        """
        Background callback manager that runs callback logic on a celery task queue,
        and stores results using a celery result backend.

        :param celery_app:
            A celery.Celery application instance that must be configured with a
            result backend. See the celery documentation for information on
            configuration options.
        :param cache_by:
            A list of zero-argument functions.  When provided, caching is enabled and
            the return values of these functions are combined with the callback
            function's input arguments, triggered inputs and source code to generate cache keys.
        :param expire:
            If provided, a cache entry will be removed when it has not been accessed
            for ``expire`` seconds.  If not provided, the lifetime of cache entries
            is determined by the default behavior of the celery result backend.
        """
        try:
            import celery  # type: ignore[reportMissingImports]; pylint: disable=import-outside-toplevel,import-error
            from celery.backends.base import (  # type: ignore[reportMissingImports]; pylint: disable=import-outside-toplevel,import-error
                DisabledBackend,
            )
        except ImportError as missing_imports:
            raise ImportError(
                """\
CeleryManager requires extra dependencies which can be installed doing

    $ pip install "dash[celery]"\n"""
            ) from missing_imports

        if not isinstance(celery_app, celery.Celery):
            raise ValueError("First argument must be a celery.Celery object")

        if isinstance(celery_app.backend, DisabledBackend):
            raise ValueError("Celery instance must be configured with a result backend")

        self.handle = celery_app
        self.expire = expire
        super().__init__(cache_by)

    def terminate_job(self, job):
        if job is None:
            return

        self.handle.control.terminate(job)

    def terminate_unhealthy_job(self, job):
        task = self.get_task(job)
        if task and task.status in ("FAILURE", "REVOKED"):
            return self.terminate_job(job)
        return False

    def job_running(self, job):
        future = self.get_task(job)
        return future and future.status in (
            "PENDING",
            "RECEIVED",
            "STARTED",
            "RETRY",
            "PROGRESS",
        )

    def make_job_fn(self, fn, progress, key=None):
        return _make_job_fn(fn, self.handle, progress, key)

    def get_task(self, job):
        if job:
            return self.handle.AsyncResult(job)

        return None

    def clear_cache_entry(self, key):
        self.handle.backend.delete(key)

    def call_job_fn(self, key, job_fn, args, context):
        task = job_fn.delay(key, self._make_progress_key(key), args, context)
        return task.task_id

    def get_progress(self, key):
        progress_key = self._make_progress_key(key)
        progress_data = self.handle.backend.get(progress_key)
        if progress_data:
            self.handle.backend.delete(progress_key)
            return json.loads(progress_data)

        return None

    def result_ready(self, key):
        return self.handle.backend.get(key) is not None

    def get_result(self, key, job):
        # Get result value
        result = self.handle.backend.get(key)
        if result is None:
            return self.UNDEFINED

        result = json.loads(result)

        # Clear result if not caching
        if self.cache_by is None:
            self.clear_cache_entry(key)
        else:
            if self.expire:
                # Set/update expiration time
                self.handle.backend.expire(key, self.expire)
        self.clear_cache_entry(self._make_progress_key(key))

        self.terminate_job(job)
        return result

    def get_updated_props(self, key):
        updated_props = self.handle.backend.get(self._make_set_props_key(key))
        if updated_props is None:
            return {}

        self.clear_cache_entry(key)

        return json.loads(updated_props)


def _make_job_fn(fn, celery_app, progress, key):  # pylint: disable=too-many-statements
    cache = celery_app.backend

    @celery_app.task(name=f"background_callback_{key}")
    def job_fn(
        result_key, progress_key, user_callback_args, context=None
    ):  # pylint: disable=too-many-statements
        def _set_progress(progress_value):
            if not isinstance(progress_value, (list, tuple)):
                progress_value = [progress_value]

            cache.set(progress_key, json.dumps(progress_value, cls=PlotlyJSONEncoder))

        maybe_progress = [_set_progress] if progress else []

        def _set_props(_id, props):
            cache.set(
                f"{result_key}-set_props",
                json.dumps({_id: props}, cls=PlotlyJSONEncoder),
            )

        ctx = copy_context()

        def run():
            c = AttributeDict(**context)  # type: ignore[reportCallIssue]
            c.ignore_register_page = False
            c.updated_props = ProxySetProps(_set_props)
            context_value.set(c)
            errored = False
            user_callback_output = None  # to help type checking
            try:
                if isinstance(user_callback_args, dict):
                    user_callback_output = fn(*maybe_progress, **user_callback_args)
                elif isinstance(user_callback_args, (list, tuple)):
                    user_callback_output = fn(*maybe_progress, *user_callback_args)
                else:
                    user_callback_output = fn(*maybe_progress, user_callback_args)
            except PreventUpdate:
                # Put NoUpdate dict directly to avoid circular imports.
                errored = True
                cache.set(
                    result_key,
                    json.dumps(
                        {"_dash_no_update": "_dash_no_update"}, cls=PlotlyJSONEncoder
                    ),
                )
            except Exception as err:  # pylint: disable=broad-except
                errored = True
                cache.set(
                    result_key,
                    json.dumps(
                        {
                            "background_callback_error": {
                                "msg": str(err),
                                "tb": traceback.format_exc(),
                            }
                        },
                    ),
                )

            if not errored:
                cache.set(
                    result_key, json.dumps(user_callback_output, cls=PlotlyJSONEncoder)
                )

        async def async_run():
            c = AttributeDict(**context)
            c.ignore_register_page = False
            c.updated_props = ProxySetProps(_set_props)
            context_value.set(c)
            errored = False
            try:
                if isinstance(user_callback_args, dict):
                    user_callback_output = await fn(
                        *maybe_progress, **user_callback_args
                    )
                elif isinstance(user_callback_args, (list, tuple)):
                    user_callback_output = await fn(
                        *maybe_progress, *user_callback_args
                    )
                else:
                    user_callback_output = await fn(*maybe_progress, user_callback_args)
            except PreventUpdate:
                # Put NoUpdate dict directly to avoid circular imports.
                errored = True
                cache.set(
                    result_key,
                    json.dumps(
                        {"_dash_no_update": "_dash_no_update"}, cls=PlotlyJSONEncoder
                    ),
                )
            except Exception as err:  # pylint: disable=broad-except
                errored = True
                cache.set(
                    result_key,
                    json.dumps(
                        {
                            "background_callback_error": {
                                "msg": str(err),
                                "tb": traceback.format_exc(),
                            }
                        },
                    ),
                )

            if asyncio.iscoroutine(user_callback_output):
                user_callback_output = await user_callback_output

            if not errored:
                cache.set(
                    result_key, json.dumps(user_callback_output, cls=PlotlyJSONEncoder)
                )

        if asyncio.iscoroutinefunction(fn):
            func = partial(ctx.run, async_run)
            asyncio.run(func())
        else:
            ctx.run(run)

    return job_fn


class CeleryLongCallbackManager(CeleryManager):
    """Deprecated: use `from dash import CeleryManager` instead."""
