"""Image processing utilities - thumbnail generation."""

import contextlib
import io
from uuid import UUID

from PIL import Image as PILImage

from app.core.storage import get_storage_client

# Thumbnail sizes (width in pixels, height proportional)
THUMBNAIL_SIZES = {
    "low": 800,  # For slow connections
    "medium": 1600,  # For medium connections
    "high": 3200,  # For fast connections
}


def generate_thumbnails(image_id: UUID, original_path: str, contents: bytes) -> dict[str, str]:
    """
    Generate thumbnails at different resolutions.

    Args:
        image_id: Image ID for naming thumbnails
        original_path: Path to original image
        contents: Original image contents

    Returns:
        Dictionary mapping quality level to thumbnail storage path
    """
    storage = get_storage_client()
    thumbnail_paths = {}

    # Load original image
    image = PILImage.open(io.BytesIO(contents))

    # Convert to RGB if necessary (for JPEG compatibility)
    if image.mode in ("RGBA", "LA", "P"):
        # Create white background for transparent images
        background = PILImage.new("RGB", image.size, (255, 255, 255))
        if image.mode == "P":
            image = image.convert("RGBA")
        background.paste(image, mask=image.split()[-1] if image.mode in ("RGBA", "LA") else None)
        image = background
    elif image.mode != "RGB":
        image = image.convert("RGB")

    # Get original dimensions
    orig_width, orig_height = image.size

    # Generate thumbnails for each size
    for quality, max_width in THUMBNAIL_SIZES.items():
        # Skip if original is smaller than thumbnail size
        if orig_width <= max_width:
            thumbnail_paths[quality] = original_path
            continue

        # Calculate proportional height
        ratio = max_width / orig_width
        new_height = int(orig_height * ratio)

        # Resize image
        thumbnail = image.resize((max_width, new_height), PILImage.Resampling.LANCZOS)

        # Convert to WebP for better compression
        output = io.BytesIO()
        thumbnail.save(output, format="WEBP", quality=85, method=6)
        output.seek(0)

        # Generate storage path
        thumbnail_path = f"thumbnails/{quality}/{image_id}.webp"

        # Upload to MinIO
        storage.put_object(
            bucket_name="webref",
            object_name=thumbnail_path,
            data=output,
            length=len(output.getvalue()),
            content_type="image/webp",
        )

        thumbnail_paths[quality] = thumbnail_path

    return thumbnail_paths


async def delete_thumbnails(thumbnail_paths: dict[str, str]) -> None:
    """
    Delete thumbnails from storage.

    Args:
        thumbnail_paths: Dictionary of quality -> path
    """
    storage = get_storage_client()
    for path in thumbnail_paths.values():
        with contextlib.suppress(Exception):
            # Log error but continue
            storage.remove_object(bucket_name="webref", object_name=path)