papiez_ipsum/src/papiezator/pope_utils.py

from papiezator.models import Pope, PopeImage, PerfectPope, DECIMAL_PLACES
from PIL import Image
from io import BytesIO
from django.core.exceptions import ObjectDoesNotExist
from random import choice
from django.http import HttpResponse
from papiezator.papiezator_settings import (
    REDIS_TTL, SAGE_REDIS, POPE_SPAN,
    POPE_CHOICE_RANGE
)

try:
    from redis import Redis
    from redis.exceptions import ConnectionError as RedisConnectionError
    redis = Redis()
except ImportError:
    redis = None


def unpopable(width, height):
    if width == 0 or height == 0:
        return True
    if (width+height) >= 9001:
        return True
    return False


#========  your friendly decorators  :3  ======================================
def redis_me(func):
    def inner(*args, **kwargs):
        import ipdb; ipdb.set_trace()
        if not redis or SAGE_REDIS:
            return func(*args, **kwargs)

        # FIXME: perhaps some better key value?
        key = (func.__name__, args)
        try:
            image = redis.get(key)
            if not image:
                image = func(*args, **kwargs)
                redis.set(key, image)
            redis.expire(key, REDIS_TTL)
            return image

        except RedisConnectionError:
            return func(*args, **kwargs)

    return inner


def habemus_papam(func):
    """Your friendly, pointless decorator ;3

    """

    def inner(aspect_ratio, pope):
        pp = PerfectPope.objects.filter(aspect_ratio=aspect_ratio, pope=pope)
        if pp: return pp[0].image

        PopeImage = func(aspect_ratio, pope)
        pp = PerfectPope(aspect_ratio=aspect_ratio, image=PopeImage, pope=pope)
        pp.save()
        return PopeImage

    return inner


def http_return_image(func):
    def inner(*args, **kwargs):
        image = func(*args, **kwargs)
        if image:
            return HttpResponse(image, content_type="image/jpeg")
        else:
            return HttpResponse("Jan Paweł II spadał z rowerka")
    return inner


# =============================================================================


@redis_me
def get_pope(width, height, pope_id):
    width, height = int(width), int(height)
    if not unpopable(width, height):
        pope = pope_or_death(Pope, id=pope_id)

        if pope:
            aspect_ratio = round(width/height, DECIMAL_PLACES)
            pope_image = select_best_pope(aspect_ratio, pope)

            if pope_image:
                return read_pope(width, height, pope_image)

    return None


@habemus_papam
def select_best_pope(aspect_ratio, pope, random=True):
    """ (float, Pope) -> PopeImage

    """
    # popes below and above this ratio
    popes = []

    popes.extend(
        PopeImage.objects.filter(
            aspect_ratio__lte=aspect_ratio,
            pope=pope).order_by('-aspect_ratio')[0:POPE_SPAN]
    )

    popes.extend(
        PopeImage.objects.filter(
            aspect_ratio__gte=aspect_ratio,
            pope=pope).order_by('aspect_ratio')[0:POPE_SPAN]
    )

    if popes:
        p = sorted(
            popes,
            key=lambda x: abs(aspect_ratio - x.aspect_ratio)
        )

        if random: return choice(p[:POPE_CHOICE_RANGE])
        else: return p[0]

    else: return None


def read_pope(width, height, pope_image):
    """ (int, int, PopeImage) -> bytes
    get pope for display
    """
    im = Image.open(pope_image.path)
    im = im.resize((width, height))
    f = BytesIO()   # FIXME: ceriously.
    im.save(f, "jpeg")
    f.seek(0)
    return f.read()


def parse_pope(path):
    im = Image.open(path)
    width, height = im.size
    aspect_ratio = round(width/height, DECIMAL_PLACES)
    return PopeImage(
        path=path,
        width=width,
        height=height,
        aspect_ratio=aspect_ratio
    )


def pope_or_death(p, **kwargs):
    try:
        x = p.objects.get(**kwargs)
    except ObjectDoesNotExist:
        x = None
    return x