"""Temporary file writer for audio downloads"""

import os
import tempfile
from typing import Optional, List

import aiofiles
from fastapi import HTTPException
from loguru import logger

from ..core.config import settings


async def cleanup_temp_files() -> None:
    """Clean up old temp files"""
    try:
        if not await aiofiles.os.path.exists(settings.temp_file_dir):
            await aiofiles.os.makedirs(settings.temp_file_dir, exist_ok=True)
            return

        # Get all temp files with stats
        files = []
        total_size = 0
        
        # Use os.scandir for sync iteration, but aiofiles.os.stat for async stats
        for entry in os.scandir(settings.temp_file_dir):
            if entry.is_file():
                stat = await aiofiles.os.stat(entry.path)
                files.append((entry.path, stat.st_mtime, stat.st_size))
                total_size += stat.st_size

        # Sort by modification time (oldest first)
        files.sort(key=lambda x: x[1])

        # Remove files if:
        # 1. They're too old
        # 2. We have too many files
        # 3. Directory is too large
        current_time = (await aiofiles.os.stat(settings.temp_file_dir)).st_mtime
        max_age = settings.max_temp_dir_age_hours * 3600

        for path, mtime, size in files:
            should_delete = False
            
            # Check age
            if current_time - mtime > max_age:
                should_delete = True
                logger.info(f"Deleting old temp file: {path}")
            
            # Check count limit
            elif len(files) > settings.max_temp_dir_count:
                should_delete = True
                logger.info(f"Deleting excess temp file: {path}")
            
            # Check size limit
            elif total_size > settings.max_temp_dir_size_mb * 1024 * 1024:
                should_delete = True
                logger.info(f"Deleting to reduce directory size: {path}")
            
            if should_delete:
                try:
                    await aiofiles.os.remove(path)
                    total_size -= size
                    logger.info(f"Deleted temp file: {path}")
                except Exception as e:
                    logger.warning(f"Failed to delete temp file {path}: {e}")

    except Exception as e:
        logger.warning(f"Error during temp file cleanup: {e}")


class TempFileWriter:
    """Handles writing audio chunks to a temp file"""
    
    def __init__(self, format: str):
        """Initialize temp file writer
        
        Args:
            format: Audio format extension (mp3, wav, etc)
        """
        self.format = format
        self.temp_file = None
        self._finalized = False
        
    async def __aenter__(self):
        """Async context manager entry"""
        # Clean up old files first
        await cleanup_temp_files()
            
        # Create temp file with proper extension
        await aiofiles.os.makedirs(settings.temp_file_dir, exist_ok=True)
        temp = tempfile.NamedTemporaryFile(
            dir=settings.temp_file_dir,
            delete=False,
            suffix=f".{self.format}",
            mode='wb'
        )
        self.temp_file = await aiofiles.open(temp.name, mode='wb')
        self.temp_path = temp.name
        temp.close()  # Close sync file, we'll use async version
        
        # Generate download path immediately
        self.download_path = f"/download/{os.path.basename(self.temp_path)}"
        return self
        
    async def __aexit__(self, exc_type, exc_val, exc_tb):
        """Async context manager exit"""
        try:
            if self.temp_file and not self._finalized:
                await self.temp_file.close()
                self._finalized = True
        except Exception as e:
            logger.error(f"Error closing temp file: {e}")
        
    async def write(self, chunk: bytes) -> None:
        """Write a chunk of audio data
        
        Args:
            chunk: Audio data bytes to write
        """
        if self._finalized:
            raise RuntimeError("Cannot write to finalized temp file")
            
        await self.temp_file.write(chunk)
        await self.temp_file.flush()
        
    async def finalize(self) -> str:
        """Close temp file and return download path
        
        Returns:
            Path to use for downloading the temp file
        """
        if self._finalized:
            raise RuntimeError("Temp file already finalized")
            
        await self.temp_file.close()
        self._finalized = True
        
        return f"/download/{os.path.basename(self.temp_path)}"