import random

from pyramid.response import Response, FileResponse
from pyramid.view import view_config
from sqlalchemy.exc import DBAPIError
from .models import Picture


@view_config(route_name='random')
def random_view(request):
    try:
        chosen = weighted_choice(request.dbsession.query(Picture.id, Picture.weight).all())
        item = request.dbsession.query(Picture).filter(Picture.id == chosen).first()
    except DBAPIError:
        return Response("", content_type='text/plain', status=500)
    directories = request.registry.settings['directories'].splitlines()
    repo, path = item.uri.split(':', 1)
    location = [i for i in directories if i.startswith(repo)][0]
    file = location[len(repo) + 1:] + path
    return FileResponse(file, request=request)


def weighted_choice(choices):
    total = sum(w for c, w in choices)
    r = random.uniform(0, total)
    upto = 0
    for c, w in choices:
        upto += w
        if upto >= r:
            return c
    assert False, "Shouldn't get here"