import os
import shutil
from fastapi import UploadFile, HTTPException, status
from pathlib import Path
from typing import BinaryIO

from app.core.config import settings
from app.models.file import File


class FileService:
    """Service for handling file operations."""

    @staticmethod
    async def save_file(upload_file: UploadFile) -> tuple[str, str, int]:
        """
        Save an uploaded file to disk.

        Args:
            upload_file: The uploaded file

        Returns:
            Tuple of (unique_filename, file_path, file_size)

        Raises:
            HTTPException: If file size exceeds the maximum allowed size
        """
        # Generate a unique filename to prevent collisions
        original_filename = upload_file.filename or "unnamed_file"
        unique_filename = File.generate_unique_filename(original_filename)

        # Define the path where the file will be saved
        file_path = settings.FILE_STORAGE_DIR / unique_filename

        # Check file size
        # First, we need to get the file size
        upload_file.file.seek(0, os.SEEK_END)
        file_size = upload_file.file.tell()
        upload_file.file.seek(0)  # Reset file position

        if file_size > settings.MAX_FILE_SIZE:
            raise HTTPException(
                status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
                detail=f"File size exceeds the maximum allowed size of {settings.MAX_FILE_SIZE} bytes",
            )

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

        return unique_filename, str(file_path), file_size

    @staticmethod
    def get_file_path(filename: str) -> Path:
        """
        Get the full path for a file.

        Args:
            filename: The filename to retrieve

        Returns:
            Path object pointing to the file
        """
        return settings.FILE_STORAGE_DIR / filename

    @staticmethod
    def file_exists(filename: str) -> bool:
        """
        Check if a file exists on disk.

        Args:
            filename: The filename to check

        Returns:
            True if the file exists, False otherwise
        """
        file_path = FileService.get_file_path(filename)
        return file_path.exists() and file_path.is_file()

    @staticmethod
    def delete_file(filename: str) -> bool:
        """
        Delete a file from disk.

        Args:
            filename: The filename to delete

        Returns:
            True if the file was deleted, False otherwise
        """
        file_path = FileService.get_file_path(filename)
        if file_path.exists() and file_path.is_file():
            file_path.unlink()
            return True
        return False

    @staticmethod
    def get_file_content(filename: str) -> BinaryIO:
        """
        Get file content as a binary file object.

        Args:
            filename: The filename to retrieve

        Returns:
            File object opened in binary mode

        Raises:
            HTTPException: If the file does not exist
        """
        file_path = FileService.get_file_path(filename)
        if not file_path.exists() or not file_path.is_file():
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="File not found",
            )

        return open(file_path, "rb")