# This file is part of photo21
# Copyright (C) 2022  Amicale des élèves de l'ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later

import logging
import os

from django.core.files.base import ContentFile
from io import BytesIO
from PIL import Image
import av

logger = logging.getLogger("photologue.utils")


def is_photo(file_obj):
    """Return True if file_obj is a valid image readable by Pillow."""
    try:
        Image.open(file_obj).verify()
        file_obj.seek(0)
        return True
    except Exception:
        file_obj.seek(0)
        return False


def is_video(file_obj):
    """Return True if file_obj is a valid video container (has at least one video stream)."""
    try:
        container = av.open(file_obj)
        ok = len(container.streams.video) > 0
        container.close()
        file_obj.seek(0)
        return ok
    except Exception:
        file_obj.seek(0)
        return False


def generate_video_thumbnail(video):
    """Extract the first frame of a video file and save it as the video thumbnail."""
    try:
        container = av.open(video.file.path)
        frame = next(container.decode(video=0))
        img = frame.to_image()
        rotation = frame.rotation
        container.close()
        if rotation:
            img = img.rotate(rotation, expand=True)
    except Exception:
        logger.error("Failed to extract video frame for thumbnail", exc_info=True)
        return

    try:
        buffer = BytesIO()
        img.save(buffer, "JPEG", quality=70, optimize=True)
        # Preserve directory structure: strip the "videos/" storage prefix so that
        # get_video_storage_path places the thumb alongside the video file.
        rel = video.file.name[len("videos/"):] if video.file.name.startswith("videos/") else video.file.name
        thumb_name = os.path.splitext(rel)[0] + "_thumb.jpg"
        video.thumbnail.save(thumb_name, ContentFile(buffer.getvalue()), save=True)
    except Exception:
        logger.error("Failed to save video thumbnail", exc_info=True)