# app/tasks/thumbnail.py
"""
Thumbnail generation tasks.

Handles generating thumbnails for images and videos,
both individually and in bulk.
"""
import logging
from datetime import datetime

from app.celery_app import celery
from app import db
from app.models import ImageRecord, ImportTask

log = logging.getLogger('celery.tasks.thumbnail')


@celery.task(bind=True, name='app.tasks.thumbnail.generate_thumbnail_task',
             max_retries=2, default_retry_delay=30)
def generate_thumbnail_task(self, image_id: int, overwrite: bool = False):
    """
    Generate thumbnail for a single image/video.

    Args:
        image_id: ID of the ImageRecord
        overwrite: Whether to overwrite existing thumbnail

    Returns:
        dict with status and thumbnail path
    """
    from app.utils.image_importer import generate_thumbnail, generate_video_thumbnail_mirrored

    record = ImageRecord.query.get(image_id)
    if not record:
        log.warning(f"Image {image_id} not found")
        return {'error': 'Image not found'}

    try:
        filepath = record.filepath
        if not filepath:
            return {'error': 'No filepath'}

        # Check if thumbnail already exists and we're not overwriting
        if record.thumb_path and not overwrite:
            import os
            if os.path.exists(record.thumb_path):
                return {'status': 'exists', 'thumb_path': record.thumb_path}

        log.debug(f"Generating thumbnail for: {filepath}")

        is_video = filepath.lower().endswith(('.mp4', '.mov', '.webm', '.avi', '.mkv'))

        if is_video:
            thumb_path = generate_video_thumbnail_mirrored(filepath)
        else:
            thumb_path = generate_thumbnail(filepath, overwrite=overwrite)

        if thumb_path:
            record.thumb_path = thumb_path
            db.session.commit()
            log.info(f"Generated thumbnail: {thumb_path}")
            return {'status': 'success', 'thumb_path': thumb_path}
        else:
            return {'status': 'failed', 'error': 'Thumbnail generation returned None'}

    except Exception as e:
        db.session.rollback()
        log.error(f"Thumbnail generation failed for {image_id}: {e}", exc_info=True)
        raise self.retry(exc=e)


@celery.task(name='app.tasks.thumbnail.regenerate_all_thumbnails')
def regenerate_all_thumbnails(batch_size: int = 100, overwrite: bool = True):
    """
    Queue thumbnail regeneration for all images.

    Processes images in batches to avoid memory issues.

    Args:
        batch_size: Number of images to process per batch
        overwrite: Whether to overwrite existing thumbnails

    Returns:
        dict with count of queued tasks
    """
    log.info("Starting bulk thumbnail regeneration")

    count = 0
    last_id = 0

    while True:
        records = ImageRecord.query.filter(
            ImageRecord.id > last_id,
            ImageRecord.filepath.isnot(None)
        ).order_by(ImageRecord.id.asc()).limit(batch_size).all()

        if not records:
            break

        for record in records:
            generate_thumbnail_task.delay(record.id, overwrite=overwrite)
            count += 1

        last_id = records[-1].id
        log.info(f"Queued {count} thumbnail tasks so far...")

    log.info(f"Thumbnail regeneration complete: queued {count} tasks")
    return {'queued': count}


@celery.task(name='app.tasks.thumbnail.regenerate_missing_thumbnails')
def regenerate_missing_thumbnails(batch_size: int = 100):
    """
    Generate thumbnails only for images that don't have them.

    Args:
        batch_size: Number of images to process per batch

    Returns:
        dict with count of queued tasks
    """
    import os

    log.info("Checking for missing thumbnails")

    count = 0
    last_id = 0

    while True:
        records = ImageRecord.query.filter(
            ImageRecord.id > last_id,
            ImageRecord.filepath.isnot(None)
        ).order_by(ImageRecord.id.asc()).limit(batch_size).all()

        if not records:
            break

        for record in records:
            # Check if thumbnail is missing
            needs_thumb = False
            if not record.thumb_path:
                needs_thumb = True
            elif not os.path.exists(record.thumb_path):
                needs_thumb = True

            if needs_thumb:
                generate_thumbnail_task.delay(record.id, overwrite=False)
                count += 1

        last_id = records[-1].id

    log.info(f"Missing thumbnail check complete: queued {count} tasks")
    return {'queued': count}