"""
Task state management
Used to track long-running tasks (e.g. graph building).
"""

import uuid
import threading
from datetime import datetime
from enum import Enum
from typing import Dict, Any, Optional
from dataclasses import dataclass, field

from ..utils.locale import t


class TaskStatus(str, Enum):
    """Task status enum"""
    PENDING = "pending"          # Waiting
    PROCESSING = "processing"    # In progress
    COMPLETED = "completed"      # Completed
    FAILED = "failed"            # Failed


@dataclass
class Task:
    """Task data class"""
    task_id: str
    task_type: str
    status: TaskStatus
    created_at: datetime
    updated_at: datetime
    progress: int = 0              # Total progress percentage 0-100
    message: str = ""              # Status message
    result: Optional[Dict] = None  # Task result
    error: Optional[str] = None    # Error info
    metadata: Dict = field(default_factory=dict)  # Extra metadata
    progress_detail: Dict = field(default_factory=dict)  # Detailed progress info

    def to_dict(self) -> Dict[str, Any]:
        """Convert to dictionary"""
        return {
            "task_id": self.task_id,
            "task_type": self.task_type,
            "status": self.status.value,
            "created_at": self.created_at.isoformat(),
            "updated_at": self.updated_at.isoformat(),
            "progress": self.progress,
            "message": self.message,
            "progress_detail": self.progress_detail,
            "result": self.result,
            "error": self.error,
            "metadata": self.metadata,
        }


class TaskManager:
    """
    Task manager
    Thread-safe task state management
    """

    _instance = None
    _lock = threading.Lock()

    def __new__(cls):
        """Singleton pattern"""
        if cls._instance is None:
            with cls._lock:
                if cls._instance is None:
                    cls._instance = super().__new__(cls)
                    cls._instance._tasks: Dict[str, Task] = {}
                    cls._instance._task_lock = threading.Lock()
        return cls._instance
    
    def create_task(self, task_type: str, metadata: Optional[Dict] = None) -> str:
        """
        Create a new task.

        Args:
            task_type: task type
            metadata: extra metadata

        Returns:
            task ID
        """
        task_id = str(uuid.uuid4())
        now = datetime.now()
        
        task = Task(
            task_id=task_id,
            task_type=task_type,
            status=TaskStatus.PENDING,
            created_at=now,
            updated_at=now,
            metadata=metadata or {}
        )
        
        with self._task_lock:
            self._tasks[task_id] = task
        
        return task_id
    
    def get_task(self, task_id: str) -> Optional[Task]:
        """Get a task"""
        with self._task_lock:
            return self._tasks.get(task_id)
    
    def update_task(
        self,
        task_id: str,
        status: Optional[TaskStatus] = None,
        progress: Optional[int] = None,
        message: Optional[str] = None,
        result: Optional[Dict] = None,
        error: Optional[str] = None,
        progress_detail: Optional[Dict] = None
    ):
        """
        Update task status.

        Args:
            task_id: task ID
            status: new status
            progress: progress
            message: message
            result: result
            error: error info
            progress_detail: detailed progress info
        """
        with self._task_lock:
            task = self._tasks.get(task_id)
            if task:
                task.updated_at = datetime.now()
                if status is not None:
                    task.status = status
                if progress is not None:
                    task.progress = progress
                if message is not None:
                    task.message = message
                if result is not None:
                    task.result = result
                if error is not None:
                    task.error = error
                if progress_detail is not None:
                    task.progress_detail = progress_detail
    
    def complete_task(self, task_id: str, result: Dict):
        """Mark task as complete"""
        self.update_task(
            task_id,
            status=TaskStatus.COMPLETED,
            progress=100,
            message=t('progress.taskComplete'),
            result=result
        )
    
    def fail_task(self, task_id: str, error: str):
        """Mark task as failed"""
        self.update_task(
            task_id,
            status=TaskStatus.FAILED,
            message=t('progress.taskFailed'),
            error=error
        )
    
    def list_tasks(self, task_type: Optional[str] = None) -> list:
        """List tasks"""
        with self._task_lock:
            tasks = list(self._tasks.values())
            if task_type:
                tasks = [t for t in tasks if t.task_type == task_type]
            return [t.to_dict() for t in sorted(tasks, key=lambda x: x.created_at, reverse=True)]
    
    def cleanup_old_tasks(self, max_age_hours: int = 24):
        """Clean up old tasks"""
        from datetime import timedelta
        cutoff = datetime.now() - timedelta(hours=max_age_hours)
        
        with self._task_lock:
            old_ids = [
                tid for tid, task in self._tasks.items()
                if task.created_at < cutoff and task.status in [TaskStatus.COMPLETED, TaskStatus.FAILED]
            ]
            for tid in old_ids:
                del self._tasks[tid]