building-interactive-voice-response-ivr-system-python-django-twilio

models.py

from django.db import models


class Theater(models.Model):

    class Meta:
        verbose_name = 'Theater'
        verbose_name_plural = 'Theaters'

    name = models.CharField(max_length=50)
    address = models.TextField()
    digits = models.PositiveSmallIntegerField(unique=True)

    def __str__(self) -> str:
        return self.name


class Movie(models.Model):

    class Meta:
        verbose_name = 'Movie'
        verbose_name_plural = 'Movies'

    title = models.CharField(max_length=50)
    digits = models.PositiveSmallIntegerField(unique=True)

    def __str__(self) -> str:
        return self.title


class Show(models.Model):

    class Meta:
        verbose_name = 'Show'
        verbose_name_plural = 'Shows'

    movie = models.ForeignKey(Movie, on_delete=models.CASCADE)
    theater = models.ForeignKey(Theater, on_delete=models.CASCADE)
    starts_at = models.DateTimeField()

views.py

import datetime

from django.core.exceptions import SuspiciousOperation
from django.http import HttpRequest, HttpResponse
from django.conf import settings
from django.utils import timezone
from django.shortcuts import reverse
from django.views.decorators.csrf import csrf_exempt
from django.views.decorators.http import require_POST
from twilio.request_validator import RequestValidator
from twilio.twiml.voice_response import VoiceResponse

from .models import Theater, Movie, Show


request_validator = RequestValidator(settings.TWILIO_AUTH_TOKEN)


def validate_django_request(request: HttpRequest):
    try:
        signature = request.META['HTTP_X_TWILIO_SIGNATURE']
    except KeyError:
        is_valid_twilio_request = False
    else:
        is_valid_twilio_request = request_validator.validate(
            signature = signature,
            uri = request.get_raw_uri(),
            params = request.POST,
        )
    if not is_valid_twilio_request:
        # Invalid request from Twilio
        raise SuspiciousOperation()


@require_POST
@csrf_exempt
def choose_theater(request: HttpRequest) -> HttpResponse:
    validate_django_request(request)
    vr = VoiceResponse()
    vr.say('Welcome to movie info!')

    with vr.gather(
        action=reverse('choose-movie'),
        finish_on_key='#',
        timeout=20,
    ) as gather:
        gather.say('Please choose a theater and press #')
        theaters = (
            Theater.objects
            .filter(digits__isnull=False)
            .order_by('digits')
        )
        for theater in theaters:
            gather.say(f'For {theater.name} at {theater.address} press {theater.digits}')

    vr.say('We did not receive your selection')
    vr.redirect('')

    return HttpResponse(str(vr), content_type='text/xml')


@require_POST
@csrf_exempt
def choose_movie(request: HttpRequest) -> HttpResponse:
    validate_django_request(request)
    vr = VoiceResponse()

    digits = request.POST.get('Digits')
    try:
        theater = Theater.objects.get(digits=digits)

    except Theater.DoesNotExist:
        vr.say('Please select a theater from the list.')
        vr.redirect(reverse('choose-theater'))

    else:
        with vr.gather(
            action=f'{reverse("list-showtimes")}?theater={theater.id}',
            finish_on_key='#',
            timeout=20,
        ) as gather:
            gather.say('Please choose a movie and press #')
            movies = (
                Movie.objects
                .filter(digits__isnull=False)
                .order_by('digits')
            )
            for movie in movies:
                gather.say(f'For {movie.title} press {movie.digits}')

        vr.say('We did not receive your selection')
        vr.redirect(reverse('choose-theater'))

    return HttpResponse(str(vr), content_type='text/xml')


@require_POST
@csrf_exempt
def list_showtimes(request: HttpRequest) -> HttpResponse:
    validate_django_request(request)
    vr = VoiceResponse()

    digits = request.POST.get('Digits')
    theater = Theater.objects.get(id=request.GET['theater'])

    # Validate the user selection
    try:
        movie = Movie.objects.get(id=digits)

    except Movie.DoesNotExist:
        vr.say('Please select a movie from the list.')
        vr.redirect(f'{reverse("choose-movie")}?theater={theater.id}')

    else:
        # User selected movie and theater, search shows in the next 12 hours:
        from_time = timezone.now()
        until_time = from_time + datetime.timedelta(hours=12)
        shows = list(
            Show.objects.filter(
                theater=theater,
                movie=movie,
                starts_at__range=(from_time, until_time),
            ).order_by('starts_at')
        )
        if len(shows) == 0:
            vr.say('Sorry, the movie is not playing any time soon in this theater.')
        else:
            showtimes = ', '.join(show.starts_at.time().strftime('%I:%M%p') for show in shows)
            vr.say(f'The movie {movie.title} will be playing at {theater.name} at {showtimes}')

        vr.say('Thank you for using movie info!')
        vr.hangup()

    return HttpResponse(str(vr), content_type='text/xml')