import os
import uuid
from werkzeug.utils import secure_filename
from PIL import Image


def allowed_file(filename, allowed_extensions):
    """Check if file has allowed extension"""
    return '.' in filename and \
           filename.rsplit('.', 1)[1].lower() in allowed_extensions


def save_image(file, upload_folder, allowed_extensions):
    """
    Save uploaded image file with validation

    Args:
        file: FileStorage object from Flask request
        upload_folder: Directory to save images
        allowed_extensions: Set of allowed file extensions

    Returns:
        str: Relative path to saved image, or None if validation fails

    Raises:
        ValueError: If file validation fails
    """
    if not file or file.filename == '':
        raise ValueError("No file provided")

    if not allowed_file(file.filename, allowed_extensions):
        raise ValueError(f"File type not allowed. Allowed types: {', '.join(allowed_extensions)}")

    # Verify it's actually an image
    try:
        img = Image.open(file.stream)
        img.verify()
        file.stream.seek(0)  # Reset stream after verification
    except Exception as e:
        raise ValueError(f"Invalid image file: {str(e)}")

    # Generate unique filename
    original_filename = secure_filename(file.filename)
    extension = original_filename.rsplit('.', 1)[1].lower()
    unique_filename = f"{uuid.uuid4()}.{extension}"

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

    # Save file
    filepath = os.path.join(upload_folder, unique_filename)
    file.save(filepath)

    # Return relative path (for storing in database)
    return f"/static/images/{unique_filename}"


def delete_image(image_path, base_folder):
    """
    Delete an image file

    Args:
        image_path: Relative path to image (e.g., /static/images/abc123.jpg)
        base_folder: Base folder for the application
    """
    if not image_path:
        return

    # Remove leading slash and construct full path
    relative_path = image_path.lstrip('/')
    full_path = os.path.join(base_folder, relative_path)

    try:
        if os.path.exists(full_path):
            os.remove(full_path)
    except Exception as e:
        # Log error but don't fail the operation
        print(f"Error deleting image {full_path}: {str(e)}")