konova/konova/models.py

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

"""
import os
import uuid

from django.contrib.auth.models import User
from django.core.exceptions import ObjectDoesNotExist
from django.utils import timezone
from django.utils.timezone import now
from django.utils.translation import gettext_lazy as _
from django.contrib.gis.db.models import MultiPolygonField
from django.db import models, transaction

from compensation.settings import COMPENSATION_IDENTIFIER_TEMPLATE, COMPENSATION_IDENTIFIER_LENGTH, \
    ECO_ACCOUNT_IDENTIFIER_TEMPLATE, ECO_ACCOUNT_IDENTIFIER_LENGTH
from ema.settings import EMA_ACCOUNT_IDENTIFIER_LENGTH, EMA_ACCOUNT_IDENTIFIER_TEMPLATE
from intervention.settings import INTERVENTION_IDENTIFIER_LENGTH, INTERVENTION_IDENTIFIER_TEMPLATE
from konova.settings import INTERVENTION_REVOCATION_DOC_PATH
from konova.utils import generators
from konova.utils.generators import generate_random_string
from user.models import UserActionLogEntry, UserAction


class UuidModel(models.Model):
    """
    Encapsules identifying via uuid
    """
    id = models.UUIDField(
        primary_key=True,
        default=uuid.uuid4,
        editable=False,
    )

    class Meta:
        abstract = True


class BaseResource(UuidModel):
    """
    A basic resource model, which defines attributes for every derived model
    """
    created = models.ForeignKey(
        UserActionLogEntry,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='+'
    )
    modified = models.ForeignKey(
        UserActionLogEntry,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='+',
        help_text="Last modified"
    )

    class Meta:
        abstract = True

    def delete(self, using=None, keep_parents=False):
        """ Base deleting of a resource

        Args:
            using ():
            keep_parents ():

        Returns:

        """
        try:
            self.created.delete()
        except (ObjectDoesNotExist, AttributeError) as e:
            # Object does not exist anymore - we can skip this
            pass
        super().delete()


class BaseObject(BaseResource):
    """
    A basic object model, which specifies BaseResource.

    Mainly used for intervention, compensation, ecoaccount
    """
    identifier = models.CharField(max_length=1000, null=True, blank=True)
    title = models.CharField(max_length=1000, null=True, blank=True)
    deleted = models.ForeignKey(UserActionLogEntry, on_delete=models.SET_NULL, null=True, blank=True, related_name='+')
    comment = models.TextField(null=True, blank=True)
    log = models.ManyToManyField(UserActionLogEntry, blank=True, help_text="Keeps all user actions of an object", editable=False)

    class Meta:
        abstract = True

    def mark_as_deleted(self, user: User):
        """ Mark an entry as deleted

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

        Args:
            user (User): The performing user

        Returns:

        """
        if self.deleted:
            # Nothing to do here
            return

        with transaction.atomic():
            action = UserActionLogEntry.objects.create(
                user=user,
                action=UserAction.DELETED,
                timestamp=timezone.now()
            )
            self.deleted = action
            self.log.add(action)
            self.save()

    def add_log_entry(self, action: UserAction, user: User, comment: str):
        """ Wraps adding of UserActionLogEntry to self.log

        Args:
            action (UserAction): The performed UserAction
            user (User): Performing user

        Returns:

        """
        user_action = UserActionLogEntry.objects.create(
            user=user,
            action=action,
            comment=comment
        )
        self.log.add(user_action)

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

        Checks whether a given user has access to this object

        Args:
            user ():

        Returns:

        """
        if hasattr(self, "users"):
            return self.users.filter(id=user.id)
        else:
            return User.objects.none()

    def generate_new_identifier(self) -> str:
        """ Generates a new identifier for the intervention object

        Returns:
            str
        """
        from compensation.models import Compensation, EcoAccount
        from intervention.models import Intervention
        from ema.models import Ema

        definitions = {
            Intervention: {
                "length": INTERVENTION_IDENTIFIER_LENGTH,
                "template": INTERVENTION_IDENTIFIER_TEMPLATE,
            },
            Compensation: {
                "length": COMPENSATION_IDENTIFIER_LENGTH,
                "template": COMPENSATION_IDENTIFIER_TEMPLATE,
            },
            EcoAccount: {
                "length": ECO_ACCOUNT_IDENTIFIER_LENGTH,
                "template": ECO_ACCOUNT_IDENTIFIER_TEMPLATE,
            },
            Ema: {
                "length": EMA_ACCOUNT_IDENTIFIER_LENGTH,
                "template": EMA_ACCOUNT_IDENTIFIER_TEMPLATE,
            },
        }

        if self.__class__ not in definitions:
            # Not defined, yet. Create fallback identifier for this case
            return generate_random_string(10)

        _now = now()
        curr_month = str(_now.month)
        curr_year = str(_now.year)
        rand_str = generate_random_string(
            length=definitions[self.__class__]["length"],
            use_numbers=True,
            use_letters_lc=False,
            use_letters_uc=True,
        )
        _str = "{}{}-{}".format(curr_month, curr_year, rand_str)
        return definitions[self.__class__]["template"].format(_str)


class DeadlineType(models.TextChoices):
    """
    Django 3.x way of handling enums for models
    """
    FINISHED = "finished", _("Finished")
    MAINTAIN = "maintain", _("Maintain")
    CONTROL = "control", _("Control")
    OTHER = "other", _("Other")


class Deadline(BaseResource):
    """
    Defines a deadline, which can be used to define dates with a semantic meaning
    """

    type = models.CharField(max_length=255, null=True, blank=True, choices=DeadlineType.choices)
    date = models.DateField(null=True, blank=True)
    comment = models.CharField(max_length=1000, null=True, blank=True)

    def __str__(self):
        return self.type

    @property
    def type_humanized(self):
        """ Returns humanized version of enum

        Used for template rendering

        Returns:

        """
        choices = DeadlineType.choices
        for choice in choices:
            if choice[0] == self.type:
                return choice[1]
        return None


def generate_document_file_upload_path(instance, filename):
    """ Generates the file upload path for certain document instances

    Documents derived from AbstractDocument need specific upload paths for their related models.

    Args:
        instance (): The document instance
        filename (): The filename

    Returns:

    """
    from compensation.models import CompensationDocument, EcoAccountDocument
    from ema.models import EmaDocument
    from intervention.models import InterventionDocument, RevocationDocument
    from konova.settings import ECO_ACCOUNT_DOC_PATH, EMA_DOC_PATH, \
        COMPENSATION_DOC_PATH, \
        INTERVENTION_DOC_PATH

    # Map document types to paths on the hard drive
    path_map = {
        InterventionDocument: INTERVENTION_DOC_PATH,
        CompensationDocument: COMPENSATION_DOC_PATH,
        EmaDocument: EMA_DOC_PATH,
        RevocationDocument: INTERVENTION_REVOCATION_DOC_PATH,
        EcoAccountDocument: ECO_ACCOUNT_DOC_PATH,
    }
    path = path_map.get(instance.__class__, None)
    if path is None:
        raise NotImplementedError("Unidentified document type: {}".format(instance.__class__))

    # RevocationDocument needs special treatment, since these files need to be stored in a subfolder of the related
    # instance's (Revocation) legaldata interventions folder
    if instance.__class__ is RevocationDocument:
        path = path.format(instance.intervention.id)
    else:
        path = path.format(instance.instance.id)
    return path + filename


class AbstractDocument(BaseResource):
    """
    Documents can be attached to compensation or intervention for uploading legal documents or pictures.
    """
    title = models.CharField(max_length=500, null=True, blank=True)
    date_of_creation = models.DateField()
    file = models.FileField()
    comment = models.TextField()

    class Meta:
        abstract = True

    def delete(self, using=None, keep_parents=False):
        """ Custom delete function to remove the real file from the hard drive

        Args:
            using ():
            keep_parents ():

        Returns:

        """
        try:
            os.remove(self.file.file.name)
        except FileNotFoundError:
            # File seems to missing anyway - continue!
            pass
        super().delete(using=using, keep_parents=keep_parents)


class Geometry(BaseResource):
    """
    Outsourced geometry model so multiple versions of the same object can refer to the same geometry if it is not changed
    """
    from konova.settings import DEFAULT_SRID
    geom = MultiPolygonField(null=True, blank=True, srid=DEFAULT_SRID)


class RecordableObject(models.Model):
    """ Wraps record related fields and functionality

    """
    # 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="+"
    )

    class Meta:
        abstract = True

    def set_unrecorded(self, user: User):
        """ Perform unrecording

        Args:
            user (User): Performing user

        Returns:

        """
        action = UserActionLogEntry.objects.create(
            user=user,
            action=UserAction.UNRECORDED
        )
        self.recorded = None
        self.save()
        self.log.add(action)

    def set_recorded(self, user: User):
        """ Perform recording

        Args:
            user (User): Performing user

        Returns:

        """
        action = UserActionLogEntry.objects.create(
            user=user,
            action=UserAction.RECORDED
        )
        self.recorded = action
        self.save()
        self.log.add(action)

    def toggle_recorded(self, user: User):
        """ Un/Record intervention

        Args:
            user (User): Performing user

        Returns:

        """
        if not self.recorded:
            self.set_recorded(user)
        else:
            self.set_unrecorded(user)


class CheckableObject(models.Model):
    # 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="+"
    )
    class Meta:
        abstract = True

    def set_unchecked(self, user: User):
        """ Perform unrecording

        Args:

        Returns:

        """
        self.checked = None
        self.save()

    def set_checked(self, user: User):
        """ Perform checking

        Args:
            user (User): Performing user

        Returns:

        """
        action = UserActionLogEntry.objects.create(
            user=user,
            action=UserAction.CHECKED
        )
        self.checked = action
        self.save()
        self.log.add(action)

    def toggle_checked(self, user: User):
        """ Un/Record intervention

        Args:
            user (User): Performing user

        Returns:

        """
        if not self.checked:
            self.set_checked(user)
        else:
            self.set_unchecked(user)


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

    class Meta:
        abstract = True

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

        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, True, True, False)
        # Check dynamically wheter there is another instance of that model, which holds this random access token
        _model = self._meta.concrete_model
        token_used_in = _model.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()