from django.core.files.storage import FileSystemStorage
from django.conf import settings
from django.core.files.base import File
from django.core.files.move import file_move_safe
from django.core.files.uploadedfile import UploadedFile, TemporaryUploadedFile
import os
import re
from typing import Optional, Any, Union

class MediaStorage(FileSystemStorage):
    _instance = None
    _counters = {}

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        kwargs['location'] = settings.MEDIA_ROOT
        kwargs['base_url'] = settings.MEDIA_URL
        super().__init__(*args, **kwargs)
    
    @classmethod
    def reset_counters(cls):
        """Reset all counters - useful for testing"""
        cls._counters = {}
    
    def get_available_name(self, name: str, max_length: Optional[int] = None) -> str:
        """
        Returns a filename that's free on the target storage system.
        Ensures proper normalization and uniqueness.
        """
        # Get the directory and filename
        directory = os.path.dirname(name)
        filename = os.path.basename(name)
        
        # Create directory if it doesn't exist
        full_dir = os.path.join(self.location, directory)
        os.makedirs(full_dir, exist_ok=True)
        
        # Split filename into root and extension
        file_root, file_ext = os.path.splitext(filename)
        
        # Extract base name without any existing numbers
        base_root = file_root.rsplit('_', 1)[0]
        
        # Use counter for this directory
        dir_key = os.path.join(directory, base_root)
        if dir_key not in self._counters:
            self._counters[dir_key] = 0
        
        self._counters[dir_key] += 1
        counter = self._counters[dir_key]
        
        new_name = f"{base_root}_{counter}{file_ext}"
        return os.path.join(directory, new_name)
    
    def _save(self, name: str, content: Union[File, UploadedFile]) -> str:
        """
        Save the file and set proper permissions
        """
        # Get the full path where the file will be saved
        full_path = self.path(name)
        directory = os.path.dirname(full_path)
        
        # Create the directory if it doesn't exist
        os.makedirs(directory, exist_ok=True)
        
        # Save the file using Django's file handling
        if isinstance(content, TemporaryUploadedFile):
            # This is a TemporaryUploadedFile
            file_move_safe(content.temporary_file_path(), full_path)
        else:
            # This is an InMemoryUploadedFile or similar
            with open(full_path, 'wb') as destination:
                if hasattr(content, 'chunks'):
                    for chunk in content.chunks():
                        destination.write(chunk)
                else:
                    destination.write(content.read())
        
        # Set proper permissions
        os.chmod(full_path, 0o644)
        os.chmod(directory, 0o755)
        
        return name