konova/intervention/models.py

"""
Author: Michel Peltriaux
Organization: Struktur- und Genehmigungsdirektion Nord, Rhineland-Palatinate, Germany
Contact: michel.peltriaux@sgdnord.rlp.de
Created on: 17.11.20

"""
from django.contrib.auth.models import User
from django.contrib.gis.db import models
from django.db import transaction
from django.utils import timezone
from django.utils.timezone import now

from intervention.settings import INTERVENTION_IDENTIFIER_LENGTH, INTERVENTION_IDENTIFIER_TEMPLATE
from konova.models import BaseObject, Geometry, UuidModel
from konova.utils import generators
from konova.utils.generators import generate_random_string
from organisation.models import Organisation
from user.models import UserActionLogEntry


class ResponsibilityData(UuidModel):
    """
    Holds intervention data about responsible organizations and their file numbers for this case

    """
    registration_office = models.ForeignKey(Organisation, on_delete=models.SET_NULL, null=True, related_name="+")
    registration_file_number = models.CharField(max_length=1000, blank=True, null=True)
    conservation_office = models.ForeignKey(Organisation, on_delete=models.SET_NULL, null=True, related_name="+")
    conservation_file_number = models.CharField(max_length=1000, blank=True, null=True)
    handler = models.CharField(max_length=500, null=True, blank=True, help_text="Refers to 'Eingriffsverursacher'")


class LegalData(UuidModel):
    """
    Holds intervention legal data such as important dates, laws or responsible handler
    """
    # Refers to "zugelassen am"
    registration_date = models.DateField(null=True, blank=True, help_text="Refers to 'Zugelassen am'")

    # Refers to "Bestandskraft am"
    binding_date = models.DateField(null=True, blank=True, help_text="Refers to 'Bestandskraft am'")

    process_type = models.CharField(max_length=500, null=True, blank=True)
    law = models.CharField(max_length=500, null=True, blank=True)


class Intervention(BaseObject):
    """
    Interventions are e.g. construction sites where nature used to be.
    """
    responsible = models.OneToOneField(
        ResponsibilityData,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='+',
        help_text="Holds data on responsible organizations ('Zulassungsbehörde', 'Eintragungsstelle')"
    )
    legal = models.OneToOneField(
        LegalData,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='+',
        help_text="Holds data on legal dates or law"
    )
    geometry = models.ForeignKey(Geometry, null=True, blank=True, on_delete=models.SET_NULL)
    documents = models.ManyToManyField("konova.Document", blank=True)

    # Checks - Refers to "Genehmigen" but optional
    checked = models.OneToOneField(
        UserActionLogEntry,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        help_text="Holds data on user and timestamp of this action",
        related_name="+"
    )

    # Refers to "verzeichnen"
    recorded = models.OneToOneField(
        UserActionLogEntry,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        help_text="Holds data on user and timestamp of this action",
        related_name="+"
    )

    # Holds which intervention is simply a newer version of this dataset
    next_version = models.ForeignKey("Intervention", null=True, blank=True, on_delete=models.DO_NOTHING)

    # Users having access on this object
    users = models.ManyToManyField(User)
    access_token = models.CharField(
        max_length=255,
        null=True,
        blank=True,
        help_text="Used for sharing access",
    )

    def __str__(self):
        return "{} ({})".format(self.identifier, self.title)

    def delete(self, *args, **kwargs):
        """ Custom delete functionality

        Does not delete from database but sets a timestamp for being deleted on and which user deleted the object

        Args:
            *args ():
            **kwargs ():

        Returns:

        """
        _now = timezone.now()
        _user = kwargs.get("user", None)

        with transaction.atomic():
            # "Delete" related compensations as well
            coms = self.compensations.all()
            for com in coms:
                com.deleted_on = _now
                com.deleted_by = _user
                com.save()

            self.deleted_on = _now
            self.deleted_by = _user
            self.save()

    @staticmethod
    def _generate_new_identifier() -> str:
        """ Generates a new identifier for the intervention object

        Returns:
            str
        """
        curr_month = str(now().month)
        curr_year = str(now().year)
        rand_str = generate_random_string(
            length=INTERVENTION_IDENTIFIER_LENGTH,
            only_numbers=True,
        )
        _str = "{}{}{}".format(curr_month, curr_year, rand_str)
        return INTERVENTION_IDENTIFIER_TEMPLATE.format(_str)

    def generate_access_token(self, make_unique: bool = False, rec_depth: int = 5):
        """ Creates a new access token for the intervention

        Tokens are not used for identification of a table row. The share logic checks the intervention id as well
        as the given token. Therefore two different interventions can hold the same access_token without problems.
        For (possible) future changes to the share logic, the make_unique parameter may be used for checking whether
        the access_token is already used in any intervention. If so, tokens will be generated as long as a free token
        can be found.

        Args:
            make_unique (bool): Perform check on uniqueness over all intervention entries
            rec_depth (int): How many tries for generating a free random token (only if make_unique)

        Returns:

        """
        # Make sure we won't end up in an infinite loop of trying to generate access_tokens
        rec_depth = rec_depth - 1
        if rec_depth < 0 and make_unique:
            raise RuntimeError(
                "Access token generating for {} does not seem to find a free random token! Aborted!".format(self.id)
            )

        # Create random token
        token = generators.generate_random_string(15)
        token_used_in = Intervention.objects.filter(access_token=token)
        # Make sure the token is not used anywhere as access_token, yet.
        # Make use of QuerySet lazy method for checking if it exists or not.
        if token_used_in and make_unique:
            self.generate_access_token(make_unique, rec_depth)
        else:
            self.access_token = token
            self.save()

    def save(self, *args, **kwargs):
        if self.identifier is None or len(self.identifier) == 0:
            # Create new identifier
            new_id = self._generate_new_identifier()
            while Intervention.objects.filter(identifier=new_id).exists():
                new_id = self._generate_new_identifier()
            self.identifier = new_id
        super().save(*args, **kwargs)

    def has_access(self, user: User):
        """ Access check

        Checks whether a given user has access to this intervention

        Args:
            user ():

        Returns:

        """
        return self.users.filter(username=user.username).exists()