"""images.py

This module contains image processing routines for the user_photos application.

"""
import datetime
import logging
from io import BytesIO
import os.path
import uuid

from django.conf import settings
from PIL import Image
from boto.s3.connection import S3Connection
from boto.s3.key import Key


logger = logging.getLogger(__name__)


def process_file(f, user):
    """Perform processing on the given uploaded image file:

    * The image is resized if necessary
    * A thumbnail version is created
    * The image and thumbnail are uploaded to an S3 bucket
    * The image and thumbnail URLs are returned as a tuple

    """
    logger.info('Processing image file for {}: {}'.format(user.username, f.name))

    unique_key = uuid.uuid4().hex
    ext = os.path.splitext(f.name)[1]
    filename = '/tmp/' + unique_key + ext
    with open(filename, 'wb') as fp:
        for chunk in f.chunks():
            fp.write(chunk)

    # Resize image if necessary
    image = Image.open(filename)
    if image.size > settings.USER_PHOTOS_MAX_SIZE:
        logger.debug('Resizing from {} to {}'.format(image.size, settings.USER_PHOTOS_MAX_SIZE))
        image.thumbnail(settings.USER_PHOTOS_MAX_SIZE, Image.ANTIALIAS)
        image.save(filename)

    # Create thumbnail
    logger.debug('Creating thumbnail')
    image = Image.open(filename)
    image.thumbnail(settings.USER_PHOTOS_THUMB_SIZE, Image.ANTIALIAS)
    thumb = BytesIO()
    image.save(thumb, format=image.format)

    # Upload both images to S3
    logger.debug('Getting connection / bucket')
    conn = S3Connection(settings.USER_PHOTOS_ACCESS_KEY,
                        settings.USER_PHOTOS_SECRET_KEY)
    bucket = conn.get_bucket(settings.USER_PHOTOS_BUCKET, validate=False)

    now = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')

    logging.debug('Uploading image')
    k1 = Key(bucket)
    k1.key = unique_key + ext
    k1.set_metadata('user', user.username)
    k1.set_metadata('date', now)
    k1.set_contents_from_filename(filename)

    logging.debug('Uploading thumbnail')
    k2 = Key(bucket)
    k2.key = '{}t{}'.format(unique_key, ext)
    k2.set_metadata('user', user.username)
    k2.set_metadata('date', now)
    k2.set_contents_from_string(thumb.getvalue())

    logging.debug('Making public')
    k1.make_public()
    k2.make_public()

    os.remove(filename)

    logger.info('Completed processing image file for {}: {}'.format(user.username, f.name))

    url_base = '{}/{}/'.format(settings.USER_PHOTOS_BASE_URL,
                               settings.USER_PHOTOS_BUCKET)

    return (url_base + k1.key, url_base + k2.key)