import os
import requests
import logging
from typing import Optional
from pathlib import Path

class PushoverError(Exception):
    """Custom exception for Pushover-related errors"""
    pass

def notify(
    message: str,
    title: Optional[str] = None,
    attachment: Optional[Path] = None,
    priority: int = 0
) -> bool:
    """
    Send a push notification via Pushover API.

    Args:
        message: The message to send
        title: Optional title (defaults to hostname)
        attachment: Optional file path to attach (supports images, PDFs etc)
        priority: Message priority (-2 to 2, default 0)
                 -2: Lowest, -1: Low, 0: Normal, 1: High, 2: Emergency

    Returns:
        bool: True if successful, False if failed

    Raises:
        PushoverError: If environment variables are missing or API call fails
    """
    # Check for required environment variables
    app_token = os.environ.get('PUSHOVER_APP_TOKEN')
    user_token = os.environ.get('PUSHOVER_USER_TOKEN')

    if not app_token or not user_token:
        raise PushoverError("Missing required environment variables: PUSHOVER_APP_TOKEN, PUSHOVER_USER_TOKEN")

    # Default title to hostname if not specified
    if title is None:
        title = os.uname().nodename

    # Prepare the POST data
    data = {
        'token': app_token,
        'user': user_token,
        'message': message,
        'title': title,
        'priority': priority
    }

    files = {}

    # Handle attachment if provided
    if attachment:
        if not attachment.exists():
            raise PushoverError(f"Attachment file does not exist: {attachment}")

        # Check file size (Pushover limit is 5MB)
        if attachment.stat().st_size > 5 * 1024 * 1024:
            raise PushoverError("Attachment exceeds Pushover's 5MB limit")

        files = {'attachment': open(attachment, 'rb')}

    try:
        response = requests.post(
            'https://api.pushover.net/1/messages.json',
            data=data,
            files=files,
            timeout=10
        )
        response.raise_for_status()
        return True

    except requests.exceptions.RequestException as e:
        logging.error(f"Failed to send Pushover notification: {str(e)}")
        return False

    finally:
        # Make sure we close the file if it was opened
        if files and 'attachment' in files:
            files['attachment'].close()

# Optional: Add rate limiting functionality
class RateLimiter:
    """Simple rate limiter for notifications"""
    def __init__(self, cooldown_seconds: int = 300):
        self.last_notification = {}
        self.cooldown = cooldown_seconds

    def can_notify(self, category: str) -> bool:
        """Check if enough time has passed since last notification in this category"""
        import time
        now = time.time()
        if category not in self.last_notification:
            self.last_notification[category] = now
            return True

        if now - self.last_notification[category] >= self.cooldown:
            self.last_notification[category] = now
            return True

        return False