konova/compensation/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.core.validators import MinValueValidator, MaxValueValidator
from django.db import transaction
from django.utils import timezone
from django.utils.timezone import now
from django.utils.translation import gettext_lazy as _

from compensation.settings import COMPENSATION_IDENTIFIER_LENGTH, COMPENSATION_IDENTIFIER_TEMPLATE
from intervention.models import Intervention, ResponsibilityData
from konova.models import BaseObject, BaseResource, Geometry, UuidModel
from konova.utils.generators import generate_random_string
from user.models import UserActionLogEntry


class Payment(BaseResource):
    """
    Holds data on a payment for an intervention (alternative to a classic compensation)
    """
    amount = models.FloatField(validators=[MinValueValidator(limit_value=0.00)])
    due_on = models.DateField(null=True)
    comment = models.CharField(
        max_length=1000,
        null=True,
        blank=True,
        help_text="Refers to german money transfer 'Verwendungszweck'",
    )
    intervention = models.ForeignKey(
        Intervention,
        null=True,
        blank=True,
        on_delete=models.CASCADE,
        related_name='payments'
    )


class CompensationState(UuidModel):
    """
    Compensations must define the state of an area before and after the compensation.
    """
    biotope_type = models.CharField(max_length=500, null=True, blank=True)
    surface = models.FloatField()

    def __str__(self):
        return "{} | {} m²".format(self.biotope_type, self.surface)


class UnitChoices(models.TextChoices):
    """
    Predefines units for selection
    """
    cm = "cm", _("cm")
    m = "m", _("m")
    km = "km", _("km")
    qm = "qm", _("m²")
    ha = "ha", _("ha")
    st = "pcs", _("Pieces")  # pieces


class CompensationAction(BaseResource):
    """
    Compensations include actions like planting trees, refreshing rivers and so on.
    """
    action_type = models.CharField(max_length=500, null=True, blank=True)
    amount = models.FloatField()
    unit = models.CharField(max_length=100, null=True, blank=True, choices=UnitChoices.choices)
    comment = models.TextField(blank=True, null=True, help_text="Additional comment")

    def __str__(self):
        return "{} | {} {}".format(self.action_type, self.amount, self.unit)

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

        Used for template rendering

        Returns:

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


class AbstractCompensation(BaseObject):
    """
    Abstract compensation model which holds basic attributes, shared by subclasses like the regular Compensation
    or EcoAccount.

    """
    responsible = models.OneToOneField(
        ResponsibilityData,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        help_text="Holds data on responsible organizations ('Zulassungsbehörde', 'Eintragungsstelle') and handler",
    )

    before_states = models.ManyToManyField(CompensationState, blank=True, related_name='+', help_text="Refers to 'Ausgangszustand Biotop'")
    after_states = models.ManyToManyField(CompensationState, blank=True, related_name='+', help_text="Refers to 'Zielzustand Biotop'")
    actions = models.ManyToManyField(CompensationAction, blank=True, help_text="Refers to 'Maßnahmen'")

    deadlines = models.ManyToManyField("konova.Deadline", blank=True, related_name="+")

    geometry = models.ForeignKey(Geometry, null=True, blank=True, on_delete=models.SET_NULL)
    documents = models.ManyToManyField("konova.Document", blank=True)

    # Holds a successor for this data
    next_version = models.ForeignKey("Compensation", null=True, blank=True, on_delete=models.DO_NOTHING)

    class Meta:
        abstract = True


class Compensation(AbstractCompensation):
    """
    Regular compensation, linked to an intervention
    """
    intervention = models.ForeignKey(
        Intervention,
        on_delete=models.CASCADE,
        null=True,
        blank=True,
        related_name='compensations'
    )

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

    @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=COMPENSATION_IDENTIFIER_LENGTH,
            only_numbers=True,
        )
        _str = "{}{}{}".format(curr_month, curr_year, rand_str)
        return COMPENSATION_IDENTIFIER_TEMPLATE.format(_str)

    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 Compensation.objects.filter(identifier=new_id).exists():
                new_id = self._generate_new_identifier()
            self.identifier = new_id
        super().save(*args, **kwargs)


class EcoAccount(AbstractCompensation):
    """
    An eco account is a kind of 'prepaid' compensation. It can be compared to an account that already has been filled
    with some kind of currency. From this account one is able to 'withdraw' currency for current projects.
    """
    # Users having access on this object
    # Not needed in regular Compensation since their access is defined by the linked intervention's access
    users = models.ManyToManyField(
        User,
        help_text="Users having access (shared with)"
    )

    # 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="+"
    )

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


class EcoAccountWithdraw(BaseResource):
    """
    A withdraw object for eco accounts
    """
    account = models.ForeignKey(
        EcoAccount,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        help_text="Withdrawn from",
        related_name="withdraws",
    )
    surface = models.FloatField(
        null=True,
        blank=True,
        help_text="Amount withdrawn (m²)",
        validators=[
            MinValueValidator(limit_value=0.00),
        ]
    )
    intervention = models.ForeignKey(
        Intervention,
        on_delete=models.CASCADE,
        null=True,
        blank=True,
        help_text="Withdrawn for",
        related_name="withdraws",
    )

    def __str__(self):
        return "{} of {}".format(self.surface, self.account)