import asyncio
import importlib
import inspect
import json
import time
from typing import Any, Callable, Dict, Optional, Sequence

from ..Convention.Runtime.Architecture import Architecture
from ..Convention.Runtime.GlobalConfig import ConsoleFrontColor, ProjectConfig
from ..CoreModules.database import (
    STATUS_COMPLETED,
    STATUS_FAILED,
    STATUS_PENDING,
    STATUS_RUNNING,
    Database,
    get_db,
)


class ClockScheduler:
    _instance: Optional["ClockScheduler"] = None

    def __init__(self) -> None:
        self._db: Database = get_db()
        self._config: ProjectConfig = Architecture.Get(ProjectConfig)
        self._logger = self._config
        self._tick_ms = max(int(self._config.FindItem("scheduler_tick_ms", 1000)), 10)
        self._batch_size = max(int(self._config.FindItem("scheduler_max_batch", 50)), 1)
        self._loop_task: Optional[asyncio.Task] = None
        self._running = False
        self._lock = asyncio.Lock()
        Architecture.Register(ClockScheduler, self, lambda: None)
        self._config.SaveProperties()

    @classmethod
    def instance(cls) -> "ClockScheduler":
        if not Architecture.Contains(ClockScheduler):
            cls._instance = ClockScheduler()
        return Architecture.Get(ClockScheduler)

    async def start(self) -> None:
        async with self._lock:
            if self._running:
                return
            self._running = True
            self._db.reset_running_tasks()
            self._loop_task = asyncio.create_task(self._run_loop())
            self._logger.Log(
                "Info",
                f"{ConsoleFrontColor.GREEN}ClockScheduler started with tick {self._tick_ms} ms{ConsoleFrontColor.RESET}",
            )

    async def stop(self) -> None:
        async with self._lock:
            if not self._running:
                return
            self._running = False
            if self._loop_task:
                self._loop_task.cancel()
                try:
                    await self._loop_task
                except asyncio.CancelledError:
                    pass
                self._loop_task = None
            self._logger.Log(
                "Info",
                f"{ConsoleFrontColor.GREEN}ClockScheduler stopped{ConsoleFrontColor.RESET}",
            )

    def register_task(
        self,
        plugin_module: str,
        plugin_class: Optional[str],
        callback_name: str,
        delay_ms: int,
        *,
        args: Optional[Sequence[Any]] = None,
        kwargs: Optional[Dict[str, Any]] = None,
    ) -> int:
        execute_at = int(time.time() * 1000) + max(delay_ms, 0)
        payload = json.dumps({
            "args": list(args) if args else [],
            "kwargs": kwargs or {},
        })
        task_id = self._db.create_scheduled_task(
            plugin_module,
            plugin_class,
            callback_name,
            payload,
            execute_at,
        )
        self._logger.Log(
            "Info",
            f"{ConsoleFrontColor.LIGHTCYAN_EX}Scheduled task {task_id} for {plugin_module}.{callback_name} at {execute_at}{ConsoleFrontColor.RESET}",
        )
        return task_id

    async def _run_loop(self) -> None:
        try:
            while self._running:
                await self._process_due_tasks()
                await asyncio.sleep(self._tick_ms / 1000)
        except asyncio.CancelledError:
            pass
        finally:
            self._running = False

    async def _process_due_tasks(self) -> None:
        now_ms = int(time.time() * 1000)
        tasks = self._db.get_due_tasks(now_ms, self._batch_size)
        for task in tasks:
            task_id = int(task["id"])
            attempts = int(task["attempts"])
            try:
                self._db.update_task_status(task_id, STATUS_RUNNING, attempts=attempts)
                await self._execute_task(task)
                self._db.update_task_status(task_id, STATUS_COMPLETED, attempts=attempts)
            except Exception as exc:  # pylint: disable=broad-except
                message = f"{type(exc).__name__}: {exc}"
                self._logger.Log(
                    "Error",
                    f"{ConsoleFrontColor.RED}Task {task_id} failed: {message}{ConsoleFrontColor.RESET}",
                )
                self._db.update_task_status(
                    task_id,
                    STATUS_FAILED,
                    attempts=attempts + 1,
                    last_error=message,
                )

    async def _execute_task(self, task: Any) -> None:
        plugin_module = task["plugin_module"]
        plugin_class = task["plugin_class"]
        callback_name = task["callback_name"]
        payload_raw = task["payload"]
        args, kwargs = self._decode_payload(payload_raw)
        callback = self._resolve_callback(plugin_module, plugin_class, callback_name)
        result = callback(*args, **kwargs)
        if inspect.isawaitable(result):
            await result

    def _resolve_callback(
        self,
        plugin_module: str,
        plugin_class: Optional[str],
        callback_name: str,
    ) -> Callable[..., Any]:
        module = importlib.import_module(plugin_module)
        if plugin_class:
            target_class = getattr(module, plugin_class)
            if Architecture.Contains(target_class):
                instance = Architecture.Get(target_class)
            else:
                instance = target_class()
            callback = getattr(instance, callback_name)
        else:
            callback = getattr(module, callback_name)
        return callback

    def _decode_payload(self, payload_raw: Optional[str]) -> tuple[list[Any], Dict[str, Any]]:
        if not payload_raw:
            return [], {}
        try:
            payload_obj = json.loads(payload_raw)
            args = payload_obj.get("args", [])
            kwargs = payload_obj.get("kwargs", {})
            if not isinstance(args, list) or not isinstance(kwargs, dict):
                raise ValueError("Invalid payload structure")
            return args, kwargs
        except Exception as exc:  # pylint: disable=broad-except
            self._logger.Log(
                "Warning",
                f"{ConsoleFrontColor.YELLOW}Failed to decode payload: {exc}{ConsoleFrontColor.RESET}",
            )
            return [], {}


def get_clock_scheduler() -> ClockScheduler:
    return ClockScheduler.instance()


__all__ = ["ClockScheduler", "get_clock_scheduler"]