import os
import shutil
from abc import ABC, abstractmethod
from pathlib import Path
from typing import Tuple

from fastapi import UploadFile

from app.core.config import settings


class StorageProvider(ABC):
    """Base abstract class for storage providers."""
    upload_folder: Path
    @abstractmethod
    async def save_file(self, file: UploadFile, destination: str) -> str:
        """Save a file to storage and return the relative path."""
        pass

    @abstractmethod
    def generate_presigned_url(self, file_path: str,
                               filename: str,
                               content_type: str,
                               expires_in: int = 300) -> Tuple[str, str]:
        """
        Generate a presigned URL for file upload.
        Returns: (upload_url, file_url)
        """
        pass

    @abstractmethod
    def get_file_url(self, file_path: str) -> str:
        """Get the URL for accessing a file."""
        pass


class LocalStorageProvider(StorageProvider):
    """Local filesystem storage provider."""

    def __init__(self, upload_folder: str, files_url_path: str):
        self.upload_folder = Path(upload_folder)
        self.files_url_path = files_url_path

        # Ensure upload directory exists
        os.makedirs(self.upload_folder, exist_ok=True)

    async def save_file(self, file: UploadFile, destination: str) -> str:
        """Save an uploaded file to the local filesystem."""
        # Ensure destination directory exists
        dest_path = self.upload_folder / destination
        os.makedirs(dest_path.parent, exist_ok=True)

        # Save the file
        with open(dest_path, "wb") as buffer:
            shutil.copyfileobj(file.file, buffer)

        # Return the relative path
        return destination

    def generate_presigned_url(self, file_path: str,
                               filename: str,
                               content_type: str,
                               expires_in: int = 300) -> Tuple[str, str]:
        """
        Generate a token-based upload URL for local storage.
        This simulates presigned URLs for local storage.
        """
        from app.utils.security import create_upload_token

        # Generate a unique token for this upload
        token = create_upload_token(file_path, content_type, expires_in)

        # The upload URL is to our custom upload endpoint
        upload_url = f"{settings.API_VERSION_STR}/uploads/{token}"

        # The file URL is where the file will be accessible after upload
        file_url = f"{self.files_url_path}/{file_path}"

        return upload_url, file_url

    def get_file_url(self, file_path: str) -> str:
        """Get the URL for accessing a file."""
        return f"{self.files_url_path}/{file_path}"