import json
import os
from typing import Callable, Optional

import yaml
from astropy import table, time

from ._dag_utils import (
    force_string,
    override_common_keys,
    generate_sha1_from_time,
)
from ..dfs import DFS
from ._dispatcher import Dispatcher

DAG_CONFIG_DIR = os.path.join(
    os.path.dirname(os.path.dirname(__file__)),
    "dag_config",
)


class BaseDAG:
    """Base class for all Directed Acyclic Graph (DAG) implementations.

    This class provides core functionality for DAG configuration, message generation,
    and task scheduling.
    """

    @staticmethod
    def generate_sha1():
        """Generate a unique SHA1 hash based on current timestamp.

        Returns
        -------
        str
            SHA1 hash string
        """
        return generate_sha1_from_time(verbose=False)

    @staticmethod
    def generate_dag_group_run(
        dag_group: str = "default-dag-group",
        batch_id: str = "default-batch",
        priority: int | str = 1,
    ):
        """Generate a DAG group run configuration.

        Parameters
        ----------
        dag_group : str, optional
            Group identifier (default: "-")
        batch_id : str, optional
            Batch identifier (default: "-")
        priority : int | str, optional
            Execution priority (default: 1)

        Returns
        -------
        dict
            Dictionary containing:
            - dag_group: Original group name
            - dag_group_run: Generated SHA1 identifier
            - batch_id: Batch identifier
            - priority: Execution priority
        """
        return dict(
            dag_group=dag_group,
            dag_group_run=BaseDAG.generate_sha1(),
            batch_id=batch_id,
            priority=priority,
            created_time=time.Time.now().isot,
        )

    @staticmethod
    def force_string(d: dict):
        return force_string(d)


class Level2DAG(BaseDAG):
    """Level 2 DAG base class.

    Base class for all Level 2 Directed Acyclic Graph (DAG) implementations.

    This class provides core functionality for DAG configuration, message generation,
    and task scheduling.
    """

    def __init__(self):
        pass

    def schedule(self, plan_basis: table.Table, data_basis: table.Table):
        """Schedule the DAG for execution.

        Parameters
        ----------
        plan_basis : table.Table
            Plan basis table
        data_basis : table.Table
            Data basis table
        """
        pass

    def generate_dag_run(self):
        """Generate a DAG run configuration.

        Returns
        -------
        dict
            Dictionary containing DAG run configuration
        """
        pass


class Level1DAG(BaseDAG):
    """Level 1 DAG base class.

    Base class for all Level 1 Directed Acyclic Graph (DAG) implementations.

    This class provides core functionality for DAG configuration, message generation,
    and execution management within the CSST dlist processing system.

    Attributes
    ----------
    dag : str
        Name of the DAG, must exist in DAG_MAP
    dag_cfg : dict
        Configuration loaded from YAML file
    dag_run_template : dict
        Message template structure loaded from JSON file

    Raises
    ------
    AssertionError
        If DAG name is not in DAG_MAP or config name mismatch
    """

    def __init__(
        self,
        dag: str,
        pattern: table.Table,
        dispatcher: Callable,
    ):
        """Initialize a DAG instance with configuration loading.

        Parameters
        ----------
        dag : str
            DAG name, must exist in DAG_MAP
        """
        # Set DAG name
        self.dag = dag
        self.pattern = pattern
        self.dispatcher = dispatcher

        # Load yaml and json config
        yml_path = os.path.join(DAG_CONFIG_DIR, f"{dag}.yml")
        json_path = os.path.join(DAG_CONFIG_DIR, f"default-dag-run.json")  # unified

        with open(yml_path, "r") as f:
            self.dag_cfg = yaml.safe_load(f)
        assert (
            self.dag_cfg["name"] == self.dag
        ), f"{self.dag_cfg['name']} != {self.dag}"  # , f"{dag_cfg} not consistent with definition in .yml file."
        with open(json_path, "r") as f:
            self.dag_run_template = json.load(f)

    def run(
        self,
        # DAG group parameters
        dag_group: str = "default-dag-group",
        batch_id: str = "default-batch",
        priority: int | str = 1,
        # plan filter
        dataset: str | None = None,
        instrument: str | None = None,
        obs_type: str | None = None,
        obs_group: str | None = None,
        obs_id: str | None = None,
        proposal_id: str | None = None,
        # data filter
        detector: str | None = None,
        filter: str | None = None,
        prc_status: str | None = None,
        qc_status: str | None = None,
        # prc paramters
        pmapname: str = "",
        ref_cat: str = "",
        extra_kwargs: Optional[dict] = None,
        # additional parameters
        force_success: bool = False,
        return_details: bool = False,
        return_data_list: bool = False,
        # no custom_id
    ):
        if self.dispatcher is Dispatcher.dispatch_obsgroup:
            assert (
                obs_group is not None
            ), "obs_group is required for obsgroup dispatcher"
            assert obs_id is None, "obs_id is not allowed for obsgroup dispatcher"
            assert detector is None, "detector is not allowed for obsgroup dispatcher"
            assert filter is None, "filter is not allowed for obsgroup dispatcher"
        if extra_kwargs is None:
            extra_kwargs = {}
        dag_group_run = self.generate_dag_group_run(
            dag_group=dag_group,
            batch_id=batch_id,
            priority=priority,
        )
        plan_basis = DFS.dfs1_find_plan_basis(
            dataset=dataset,
            instrument=instrument,
            obs_type=obs_type,
            obs_group=obs_group,
            obs_id=obs_id,
            proposal_id=proposal_id,
        )
        data_basis = DFS.dfs1_find_level0_basis(
            dataset=dataset,
            instrument=instrument,
            obs_type=obs_type,
            obs_group=obs_group,
            obs_id=obs_id,
            detector=detector,
            filter=filter,
            prc_status=prc_status,
            qc_status=qc_status,
        )
        plan_basis, data_basis = self.filter_basis(plan_basis, data_basis)
        dag_run_list = self.schedule(
            dag_group_run=dag_group_run,
            data_basis=data_basis,
            plan_basis=plan_basis,
            force_success=force_success,
            return_data_list=return_data_list,
            # directly passed to dag_run's
            pmapname=pmapname,
            ref_cat=ref_cat,
            extra_kwargs=extra_kwargs,
        )
        if return_details:
            return dag_group_run, dag_run_list
        else:
            return dag_group_run, [_["dag_run"] for _ in dag_run_list]

    def filter_basis(self, plan_basis, data_basis):
        # filter data basis via pattern
        filtered_data_basis = table.join(
            self.pattern,
            data_basis,
            keys=self.pattern.colnames,
            join_type="inner",
        )
        # sort via obs_id
        filtered_data_basis.sort(keys=["dataset", "obs_id", "detector"])
        if len(filtered_data_basis) == 0:
            return plan_basis[:0], filtered_data_basis
        u_data_basis = table.unique(filtered_data_basis["dataset", "obs_id"])
        # filter plan basis via data basis
        filtered_plan_basis = table.join(
            u_data_basis,
            plan_basis,
            keys=["dataset", "obs_id"],
            join_type="inner",
        )
        # sort via obs_id
        filtered_plan_basis.sort(keys=["dataset", "obs_id"])
        return filtered_plan_basis, filtered_data_basis

    def schedule(
        self,
        dag_group_run: dict,  # dag_group, dag_group_run
        data_basis: table.Table,
        plan_basis: table.Table,
        force_success: bool = False,
        return_data_list: bool = False,
        **kwargs,
    ) -> list[dict]:
        """Schedule tasks for DAG execution.

        This method filters plan and data basis, dispatches tasks, and generates
        DAG run messages for successful tasks.

        Parameters
        ----------
        dag_group_run : dict
            DAG group run configuration containing:
            - dag_group: Group identifier
            - dag_group_run: SHA1 identifier for this run
            - batch_id: Batch identifier
            - priority: Execution priority
        data_basis : table.Table
            Table of data records to process
        plan_basis : table.Table
            Table of plan records to execute
        force_success : bool, optional
            If True, generate DAG run messages for all tasks, even if they failed
            (default: False)
        return_data_list : bool, optional
            If True, fill the data_list parameter with the data_basis records
            (default: False)
        **kwargs
            Additional keyword arguments passed to `dag_run`

        Returns
        -------
        list[dict]:
            A tuple containing:
            - List of task dictionaries with DAG run messages added for successful tasks
            - Set of obs_id strings for tasks that failed or were skipped
        """
        # filter plan and data basis
        filtered_plan_basis, filtered_data_basis = self.filter_basis(
            plan_basis, data_basis
        )
        # dispatch tasks
        task_list = self.dispatcher(filtered_plan_basis, filtered_data_basis)
        for this_task in task_list:
            # only convert success tasks
            if force_success or this_task["success"]:
                dag_run = self.generate_dag_run(
                    **dag_group_run,
                    **this_task["task"],
                    **kwargs,
                )
                this_task["dag_run"] = dag_run
                if return_data_list:
                    this_task["dag_run"]["data_list"] = [
                        list(this_task["relevant_data"]["_id"])
                    ]
            else:
                this_task["dag_run"] = None
        return task_list

    def generate_dag_run(self, **kwargs) -> dict:
        """Generate a complete DAG run message.

        Parameters
        ----------
        kwargs : dict
            Additional keyword arguments to override.

        Returns
        -------
        dict
            Complete DAG run message

        Raises
        ------
        AssertionError
            If any key is not in the message template
        """
        # copy template
        dag_run = self.dag_run_template.copy()
        # update values
        dag_run = override_common_keys(dag_run, kwargs)
        # set hash
        dag_run = override_common_keys(
            dag_run,
            {
                "dag": self.dag,
                "dag_run": self.generate_sha1(),
            },
        )
        # It seems that the dag_run_template is already stringified,
        # so we don't need to force_string here.
        # force values to be string
        dag_run = self.force_string(dag_run)
        return dag_run