🚧(backend) generate pin code for existing rooms

To ensure consistency, generate a pin code for existing
rooms in db.

Not sure of this approach.

src/backend/core/api/serializers.py

@@ -141,6 +141,13 @@ class RoomSerializer(serializers.ModelSerializer):
                 ),
             }
 
+            # Todo - discuss this part, retrieve phone number from a setting? Dynamically?
+            # Todo - is it the right place?
+            # Todo - discuss the method `to_representation` which is quite dirty IMO
+            pin_code = self.instance.pin_code
+            if pin_code is not None:
+                output["livekit"]["sip"] = {"pin_code": pin_code, "phone_number": "wip"}
+
         output["is_administrable"] = is_admin
 
         return output

src/backend/core/migrations/0010_alter_resourceaccess_options_alter_user_options.py

@@ -0,0 +1,21 @@
+# Generated by Django 5.1.4 on 2025-01-12 22:30
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0009_alter_recording_status'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='resourceaccess',
+            options={'ordering': ('-created_at',), 'verbose_name': 'Resource access', 'verbose_name_plural': 'Resource accesses'},
+        ),
+        migrations.AlterModelOptions(
+            name='user',
+            options={'ordering': ('-created_at',), 'verbose_name': 'user', 'verbose_name_plural': 'users'},
+        ),
+    ]

src/backend/core/migrations/0011_room_pin_code.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.1.4 on 2025-01-12 22:34
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0010_alter_resourceaccess_options_alter_user_options'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='room',
+            name='pin_code',
+            field=models.CharField(blank=True, help_text="Unique n-digit code that identifies this room. Automatically generated on creation. Displayed with '#' suffix.", max_length=100, null=True, unique=True, verbose_name='Room PIN code'),
+        ),
+    ]

src/backend/core/migrations/0012_generate_room_pin_code.py

@@ -0,0 +1,34 @@
+from django.db import migrations
+import random
+
+
+def generate_pin_for_rooms(apps, schema_editor):
+    """Generate unique 9-digit PIN codes for existing rooms.
+
+    The PIN code is required for upcoming SIP telephony features.
+    """
+    Room = apps.get_model('core', 'Room')
+    rooms_without_pin = Room.objects.filter(pin_code__isnull=True)
+
+    def generate_pin():
+        while True:
+            pin = str(random.randint(0, 999999999)).zfill(9)
+            if not Room.objects.filter(pin_code=pin).exists():
+                return pin
+
+    for room in rooms_without_pin:
+        room.pin_code = generate_pin()
+        room.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('core', '0011_room_pin_code'),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            generate_pin_for_rooms,
+            reverse_code=migrations.RunPython.noop
+        ),
+    ]

src/backend/core/models.py

@@ -11,13 +11,15 @@ from django.contrib.auth import models as auth_models
 from django.contrib.auth.base_user import AbstractBaseUser
 from django.core import mail, validators
 from django.core.exceptions import PermissionDenied, ValidationError
-from django.db import models
+from django.db import IntegrityError, models
 from django.utils.functional import lazy
 from django.utils.text import capfirst, slugify
 from django.utils.translation import gettext_lazy as _
 
 from timezone_field import TimeZoneField
 
+from core import utils
+
 logger = getLogger(__name__)
 
 
@@ -361,13 +363,23 @@ class Room(Resource):
         primary_key=True,
     )
     slug = models.SlugField(max_length=100, blank=True, null=True, unique=True)
-
     configuration = models.JSONField(
         blank=True,
         default=dict,
         verbose_name=_("Visio room configuration"),
         help_text=_("Values for Visio parameters to configure the room."),
     )
+    pin_code = models.CharField(
+        max_length=100,
+        unique=True,
+        blank=True,
+        null=True,
+        verbose_name=_("Room PIN code"),
+        help_text=_(
+            "Unique n-digit code that identifies this room. Automatically generated on creation."
+            " Displayed with '#' suffix."
+        ),
+    )
 
     class Meta:
         db_table = "meet_room"
@@ -378,6 +390,23 @@ class Room(Resource):
     def __str__(self):
         return capfirst(self.name)
 
+    def save(self, *args, **kwargs):
+        """Generate a unique n-digit pin code for new rooms.
+
+        This uses the DB to ensure uniqueness of the code. Better than checking separately
+        with the DB and then saving, which introduces a race condition.
+        """
+
+        if self.pk or self.pin_code:
+            return super().save(*args, **kwargs)
+
+        while True:
+            try:
+                self.pin_code = utils.generate_pin_code(n=settings.ROOM_PIN_CODE_LENGTH)
+                return super().save(*args, **kwargs)
+            except IntegrityError:
+                continue
+
     def clean_fields(self, exclude=None):
         """
         Automatically generate the slug from the name and make sure it does not look like a UUID.

src/backend/core/utils.py

@@ -15,6 +15,11 @@ from django.conf import settings
 from livekit.api import AccessToken, VideoGrants
 
 
+def generate_pin_code(n: int) -> str:
+    """Generate a n-digit pin code"""
+    return f"{''.join([str(random.randint(0, 9)) for _ in range(n)])}"
+
+
 def generate_color(identity: str) -> str:
     """Generates a consistent HSL color based on a given identity string.
 

src/backend/meet/settings.py

@@ -483,6 +483,18 @@ class Base(Configuration):
     )
     BREVO_API_CONTACT_ATTRIBUTES = values.DictValue({"VISIO_USER": True})
 
+    # SIP Telephony
+    ROOM_PIN_CODE_LENGTH = values.PositiveIntegerValue(
+        9,  # this value cannot exceed 100 digits due to database constraints
+        environ_name="ROOM_PIN_CODE_LENGTH",
+        environ_prefix=None,
+    )
+    ROOM_PIN_CODE_GENERATION_MAX_RETRY = values.PositiveIntegerValue(
+        3,
+        environ_name="ROOM_PIN_CODE_GENERATION_MAX_RETRY",
+        environ_prefix=None,
+    )
+
     # pylint: disable=invalid-name
     @property
     def ENVIRONMENT(self):