shiftregister/shiftregister/app/models.py

from django.db import models
import secrets
from django.shortcuts import reverse
from datetime import timedelta
from django.utils import timezone
from django.db.models import F, Count, Q, ExpressionWrapper


class Room(models.Model):
    name = models.CharField(max_length=200, primary_key=True)
    required_helpers = models.IntegerField()

    def __str__(self):
        return self.name


class Shift(models.Model):
    room = models.ForeignKey(Room, on_delete=models.RESTRICT)
    start_at = models.DateTimeField()
    duration = models.DurationField()
    # todo: add helper amount override field
    def __str__(self):
        return f"{self.room.name}: {self.start_at}"
    def has_ended(self):
        return (self.start_at + self.duration) < timezone.now()
    def is_running(self):
        return  (self.start_at <=timezone.now()) and (not self.has_ended())


class Helper(models.Model):
    # todo: add propper phone number validation, maybe even country code?
    phone = models.CharField(max_length=200, primary_key=True)
    name = models.CharField(max_length=200)
    # change this to a generic state variable to allow for number blocking/account deactivation?
    number_validated = models.BooleanField(default=False)

    def __str__(self):
        return self.name

    def send_confirmation(self):
        (token, created) = LoginToken.objects.get_or_create(helper=self)
        text = f"Hallo {self.name}, hier ist dein Registrierungslink zum Kontaktfestival http://short.url{token.get_absolute_url()}"
        msg = Message(to=self, text=text)
        msg.save()
        return token
    
    # current or next shift
    def important_shift(self):
        ret = ShiftRegistration.objects.annotate(
                shift_end=ExpressionWrapper(
                    F("shift__start_at") + F("shift__duration"),
                    output_field=models.DateTimeField(),
                )).filter(helper=self, shift_end__gte=timezone.now()).order_by("shift__start_at").first()
        if ret:
            return ret.shift



class ShiftRegistration(models.Model):
    class Meta:
        unique_together = (("shift", "helper"),)

    # use restrict for now as Model.delete is not called
    shift = models.ForeignKey(Shift, on_delete=models.RESTRICT)
    helper = models.ForeignKey(Helper, on_delete=models.CASCADE)

    def can_cancel(self):
        return self.shift.start_at > (timezone.now() + timedelta(hours=4))


class Message(models.Model):
    # remove limit and send long messages in multiple messages?
    text = models.CharField(max_length=160)
    to = models.ForeignKey(Helper, on_delete=models.CASCADE)

    def __str__(self):
        return f"{self.to.name}: {self.text}"


def gen_token():
    return secrets.token_urlsafe(20)


class LoginToken(models.Model):
    id = models.CharField(
        max_length=20, primary_key=True, default=gen_token, editable=False
    )
    helper = models.ForeignKey(Helper, on_delete=models.CASCADE)

    def get_absolute_url(self):
        return reverse("token_login", kwargs={"token": self.id})