meet/src/backend/core/models.py

"""
Declare and configure the models for the Meet core application
"""

import uuid
from logging import getLogger
from typing import List

from django.conf import settings
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.utils.functional import lazy
from django.utils.text import capfirst, slugify
from django.utils.translation import gettext_lazy as _

from timezone_field import TimeZoneField

logger = getLogger(__name__)


class RoleChoices(models.TextChoices):
    """Role choices."""

    MEMBER = "member", _("Member")
    ADMIN = "administrator", _("Administrator")
    OWNER = "owner", _("Owner")

    @classmethod
    def check_administrator_role(cls, role):
        """Check if a role is administrator."""
        return role in [cls.ADMIN, cls.OWNER]

    @classmethod
    def check_owner_role(cls, role):
        """Check if a role is owner."""
        return role == cls.OWNER


class RecordingStatusChoices(models.TextChoices):
    """Enumeration of possible states for a recording operation."""

    INITIATED = "initiated", _("Initiated")
    ACTIVE = "active", _("Active")
    STOPPED = "stopped", _("Stopped")
    SAVED = "saved", _("Saved")
    ABORTED = "aborted", _("Aborted")
    FAILED_TO_START = "failed_to_start", _("Failed to Start")
    FAILED_TO_STOP = "failed_to_stop", _("Failed to Stop")

    @classmethod
    def is_final(cls, status):
        """Determine if the recording status represents a final state.

        A final status indicates the recording flow has completed, either
        successfully or unsuccessfully.
        """

        return status in {
            cls.STOPPED,
            cls.SAVED,
            cls.ABORTED,
            cls.FAILED_TO_START,
            cls.FAILED_TO_STOP,
        }

    @classmethod
    def is_unsuccessful(cls, status):
        """Determine if the recording status represents an unsuccessful state."""
        return status in {cls.ABORTED, cls.FAILED_TO_START, cls.FAILED_TO_STOP}


class RecordingModeChoices(models.TextChoices):
    """Recording mode choices."""

    SCREEN_RECORDING = "screen_recording", _("SCREEN_RECORDING")
    TRANSCRIPT = "transcript", _("TRANSCRIPT")


class BaseModel(models.Model):
    """
    Serves as an abstract base model for other models, ensuring that records are validated
    before saving as Django doesn't do it by default.

    Includes fields common to all models: a UUID primary key and creation/update timestamps.
    """

    id = models.UUIDField(
        verbose_name=_("id"),
        help_text=_("primary key for the record as UUID"),
        primary_key=True,
        default=uuid.uuid4,
        editable=False,
    )
    created_at = models.DateTimeField(
        verbose_name=_("created on"),
        help_text=_("date and time at which a record was created"),
        auto_now_add=True,
        editable=False,
    )
    updated_at = models.DateTimeField(
        verbose_name=_("updated on"),
        help_text=_("date and time at which a record was last updated"),
        auto_now=True,
        editable=False,
    )

    class Meta:
        abstract = True

    def save(self, *args, **kwargs):
        """Call `full_clean` before saving."""
        self.full_clean()
        super().save(*args, **kwargs)


class User(AbstractBaseUser, BaseModel, auth_models.PermissionsMixin):
    """User model to work with OIDC only authentication."""

    sub_validator = validators.RegexValidator(
        regex=r"^[\w.@+-]+\Z",
        message=_(
            "Enter a valid sub. This value may contain only letters, "
            "numbers, and @/./+/-/_ characters."
        ),
    )

    sub = models.CharField(
        _("sub"),
        help_text=_(
            "Required. 255 characters or fewer. Letters, numbers, and @/./+/-/_ characters only."
        ),
        max_length=255,
        unique=True,
        validators=[sub_validator],
        blank=True,
        null=True,
    )
    email = models.EmailField(_("identity email address"), blank=True, null=True)

    # Unlike the "email" field which stores the email coming from the OIDC token, this field
    # stores the email used by staff users to log in to the admin site
    admin_email = models.EmailField(
        _("admin email address"), unique=True, blank=True, null=True
    )

    language = models.CharField(
        max_length=10,
        choices=lazy(lambda: settings.LANGUAGES, tuple)(),
        default=settings.LANGUAGE_CODE,
        verbose_name=_("language"),
        help_text=_("The language in which the user wants to see the interface."),
    )
    timezone = TimeZoneField(
        choices_display="WITH_GMT_OFFSET",
        use_pytz=False,
        default=settings.TIME_ZONE,
        help_text=_("The timezone in which the user wants to see times."),
    )
    is_device = models.BooleanField(
        _("device"),
        default=False,
        help_text=_("Whether the user is a device or a real user."),
    )
    is_staff = models.BooleanField(
        _("staff status"),
        default=False,
        help_text=_("Whether the user can log into this admin site."),
    )
    is_active = models.BooleanField(
        _("active"),
        default=True,
        help_text=_(
            "Whether this user should be treated as active. "
            "Unselect this instead of deleting accounts."
        ),
    )

    objects = auth_models.UserManager()

    USERNAME_FIELD = "admin_email"
    REQUIRED_FIELDS = []

    class Meta:
        db_table = "meet_user"
        verbose_name = _("user")
        verbose_name_plural = _("users")

    def __str__(self):
        return self.email or self.admin_email or str(self.id)

    def email_user(self, subject, message, from_email=None, **kwargs):
        """Email this user."""
        if not self.email:
            raise ValueError("User has no email address.")
        mail.send_mail(subject, message, from_email, [self.email], **kwargs)

    def get_teams(self):
        """
        Get list of teams in which the user is, as a list of strings.
        Must be cached if retrieved remotely.
        """
        return []

    @property
    def email_anonymized(self):
        """Anonymize the email address by replacing the local part with asterisks."""
        if not self.email:
            return ""
        return f"***@{self.email.split('@')[1]}"


def get_resource_roles(resource: models.Model, user: User) -> List[str]:
    """
    Get all roles assigned to a user for a specific resource, including team-based roles.

    Args:
        resource: The resource to check permissions for
        user: The user to get roles for

    Returns:
        List of role strings assigned to the user
    """
    if not user.is_authenticated:
        return []

    # Use pre-annotated roles if available from viewset optimization
    if hasattr(resource, "user_roles"):
        return resource.user_roles or []

    try:
        return list(
            resource.accesses.filter_user(user)
            .values_list("role", flat=True)
            .distinct()
        )
    except (IndexError, models.ObjectDoesNotExist):
        return []


class Resource(BaseModel):
    """Model to define access control"""

    is_public = models.BooleanField(default=settings.RESOURCE_DEFAULT_IS_PUBLIC)
    users = models.ManyToManyField(
        User,
        through="ResourceAccess",
        through_fields=("resource", "user"),
        related_name="resources",
    )

    class Meta:
        db_table = "meet_resource"
        verbose_name = _("Resource")
        verbose_name_plural = _("Resources")

    def __str__(self):
        try:
            return self.name
        except AttributeError:
            return f"Resource {self.id!s}"

    def get_role(self, user):
        """
        Determine the role of a given user in this resource.
        """
        if not user or not user.is_authenticated:
            return None

        role = None
        for access in self.accesses.filter(user=user):
            if access.role == RoleChoices.OWNER:
                return RoleChoices.OWNER
            if access.role == RoleChoices.ADMIN:
                role = RoleChoices.ADMIN
            if access.role == RoleChoices.MEMBER and role != RoleChoices.ADMIN:
                role = RoleChoices.MEMBER
        return role

    def is_administrator(self, user):
        """
        Check if a user is administrator of the resource.

        Users carrying the "owner" role are considered as administrators a fortiori.
        """
        return RoleChoices.check_administrator_role(self.get_role(user))

    def is_owner(self, user):
        """Check if a user is owner of the resource."""
        return RoleChoices.check_owner_role(self.get_role(user))


class ResourceAccess(BaseModel):
    """Link table between resources and users"""

    resource = models.ForeignKey(
        Resource,
        on_delete=models.CASCADE,
        related_name="accesses",
    )
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name="accesses")
    role = models.CharField(
        max_length=20, choices=RoleChoices.choices, default=RoleChoices.MEMBER
    )

    class Meta:
        db_table = "meet_resource_access"
        verbose_name = _("Resource access")
        verbose_name_plural = _("Resource accesses")
        constraints = [
            models.UniqueConstraint(
                fields=["user", "resource"],
                name="resource_access_unique_user_resource",
                violation_error_message=_(
                    "Resource access with this User and Resource already exists."
                ),
            ),
        ]

    def __str__(self):
        role = capfirst(self.get_role_display())
        try:
            resource = self.resource.name
        except AttributeError:
            resource = f"resource {self.resource_id!s}"

        return f"{role:s} role for {self.user!s} on {resource:s}"

    def save(self, *args, **kwargs):
        """Make sure we keep at least one owner for the resource."""
        if self.pk and self.role != RoleChoices.OWNER:
            accesses = self._meta.model.objects.filter(
                resource=self.resource, role=RoleChoices.OWNER
            ).only("pk")
            if len(accesses) == 1 and accesses[0].pk == self.pk:
                raise PermissionDenied("A resource should keep at least one owner.")
        return super().save(*args, **kwargs)

    def delete(self, *args, **kwargs):
        """Disallow deleting the last of the Mohicans."""
        if (
            self.role == RoleChoices.OWNER
            and self._meta.model.objects.filter(
                resource=self.resource, role=RoleChoices.OWNER
            ).count()
            == 1
        ):
            raise PermissionDenied("A resource should keep at least one owner.")
        return super().delete(*args, **kwargs)


class Room(Resource):
    """Model for one room"""

    name = models.CharField(max_length=500)
    resource = models.OneToOneField(
        Resource,
        on_delete=models.CASCADE,
        parent_link=True,
        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."),
    )

    class Meta:
        db_table = "meet_room"
        ordering = ("name",)
        verbose_name = _("Room")
        verbose_name_plural = _("Rooms")

    def __str__(self):
        return capfirst(self.name)

    def clean_fields(self, exclude=None):
        """
        Automatically generate the slug from the name and make sure it does not look like a UUID.

        We don't want any overlapping between the `slug` and the `id` fields because they can
        both be used to get a room detail view on the API.
        """
        self.slug = slugify(self.name)
        try:
            uuid.UUID(self.slug)
        except ValueError:
            pass
        else:
            raise ValidationError({"name": f'Room name "{self.name:s}" is reserved.'})
        super().clean_fields(exclude=exclude)


class BaseAccessManager(models.Manager):
    """Base manager for handling resource access control."""

    def filter_user(self, user):
        """Filter accesses for a given user, including both direct and team-based access."""
        return self.filter(models.Q(user=user) | models.Q(team__in=user.get_teams()))


class BaseAccess(BaseModel):
    """Base model for accesses to handle resources."""

    user = models.ForeignKey(
        User,
        on_delete=models.CASCADE,
        null=True,
        blank=True,
    )
    team = models.CharField(max_length=100, blank=True)
    role = models.CharField(
        max_length=20, choices=RoleChoices.choices, default=RoleChoices.MEMBER
    )

    objects = BaseAccessManager()

    class Meta:
        abstract = True

    def _get_abilities(self, resource, user):
        """
        Compute and return abilities for a given user taking into account
        the current state of the object.
        """

        roles = get_resource_roles(resource, user)

        is_owner = RoleChoices.OWNER in roles
        has_privileges = is_owner or RoleChoices.ADMIN in roles

        # Default values for unprivileged users
        set_role_to = set()
        can_delete = False

        # Special handling when modifying an owner's access
        if self.role == RoleChoices.OWNER:
            # Prevent orphaning the resource
            can_delete = (
                is_owner
                and resource.accesses.filter(role=RoleChoices.OWNER).count() > 1
            )
            if can_delete:
                set_role_to = {RoleChoices.ADMIN, RoleChoices.OWNER, RoleChoices.MEMBER}
        elif has_privileges:
            can_delete = True
            set_role_to = {RoleChoices.ADMIN, RoleChoices.MEMBER}
            if is_owner:
                set_role_to.add(RoleChoices.OWNER)

        # Remove the current role as we don't want to propose it as an option
        set_role_to.discard(self.role)

        return {
            "destroy": can_delete,
            "update": bool(set_role_to),
            "partial_update": bool(set_role_to),
            "retrieve": bool(roles),
            "set_role_to": sorted(r.value for r in set_role_to),
        }


class Recording(BaseModel):
    """Model for recordings that take place in a room"""

    room = models.ForeignKey(
        Room,
        on_delete=models.CASCADE,
        related_name="recordings",
        verbose_name=_("Room"),
    )
    status = models.CharField(
        max_length=20,
        choices=RecordingStatusChoices.choices,
        default=RecordingStatusChoices.INITIATED,
    )
    worker_id = models.CharField(
        max_length=255,
        null=True,
        blank=True,
        verbose_name=_("Worker ID"),
        help_text=_(
            "Enter an identifier for the worker recording."
            "This ID is retained even when the worker stops, allowing for easy tracking."
        ),
    )
    mode = models.CharField(
        max_length=20,
        choices=RecordingModeChoices.choices,
        default=RecordingModeChoices.SCREEN_RECORDING,
        verbose_name=_("Recording mode"),
        help_text=_("Defines the mode of recording being called."),
    )

    class Meta:
        db_table = "meet_recording"
        ordering = ("-created_at",)
        verbose_name = _("Recording")
        verbose_name_plural = _("Recordings")
        constraints = [
            models.UniqueConstraint(
                fields=["room"],
                condition=models.Q(
                    status__in=[
                        RecordingStatusChoices.ACTIVE,
                        RecordingStatusChoices.INITIATED,
                    ]
                ),
                name="unique_initiated_or_active_recording_per_room",
            )
        ]

    def __str__(self):
        return f"Recording {self.id} ({self.status})"

    def get_abilities(self, user):
        """Compute and return abilities for a given user on the recording."""

        roles = set(get_resource_roles(self, user))

        is_owner_or_admin = bool(
            roles.intersection({RoleChoices.OWNER, RoleChoices.ADMIN})
        )

        is_final_status = RecordingStatusChoices.is_final(self.status)

        return {
            "destroy": is_owner_or_admin and is_final_status,
            "partial_update": False,
            "retrieve": is_owner_or_admin,
            "stop": is_owner_or_admin and not is_final_status,
            "update": False,
        }

    def is_savable(self) -> bool:
        """Determine if the recording can be saved based on its current status."""

        return self.status in {
            RecordingStatusChoices.ACTIVE,
            RecordingStatusChoices.STOPPED,
        }


class RecordingAccess(BaseAccess):
    """Relation model to give access to a recording for a user or a team with a role.

    Recording Status Flow:
    1. INITIATED: Initial state when recording is requested
    2. ACTIVE: Recording is currently in progress
    3. STOPPED: Recording has been stopped by user/system
    4. SAVED: Recording has been successfully processed and stored

    Error States:
    - FAILED_TO_START: Worker failed to initialize recording
    - FAILED_TO_STOP: Worker failed during stop operation
    - ABORTED: Recording was terminated before completion

    Warning: Worker failures may lead to database inconsistency between the actual
    recording state and its status in the database.
    """

    recording = models.ForeignKey(
        Recording,
        on_delete=models.CASCADE,
        related_name="accesses",
    )

    class Meta:
        db_table = "meet_recording_access"
        ordering = ("-created_at",)
        verbose_name = _("Recording/user relation")
        verbose_name_plural = _("Recording/user relations")
        constraints = [
            models.UniqueConstraint(
                fields=["user", "recording"],
                condition=models.Q(user__isnull=False),  # Exclude null users
                name="unique_recording_user",
                violation_error_message=_("This user is already in this recording."),
            ),
            models.UniqueConstraint(
                fields=["team", "recording"],
                condition=models.Q(team__gt=""),  # Exclude empty string teams
                name="unique_recording_team",
                violation_error_message=_("This team is already in this recording."),
            ),
            models.CheckConstraint(
                condition=models.Q(user__isnull=False, team="")
                | models.Q(user__isnull=True, team__gt=""),
                name="check_recording_access_either_user_or_team",
                violation_error_message=_("Either user or team must be set, not both."),
            ),
        ]

    def __str__(self):
        return f"{self.user!s} is {self.role:s} in {self.recording!s}"

    def get_abilities(self, user):
        """
        Compute and return abilities for a given user on the recording access.
        """
        return self._get_abilities(self.recording, user)