import datetime
import pathlib
import uuid

from django.conf import settings
from django.core.validators import FileExtensionValidator
from django.db import models, transaction
from django.urls import reverse
from django.utils.translation import gettext as _


class UserModel(models.Model):
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        verbose_name=_("User"),
        editable=False,
    )

    class Meta:
        abstract = True


class CustomModel(UserModel):
    @property
    def adding(self):
        return self._state.adding

    class Meta:
        abstract = True


class Account(CustomModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=64, default=_("Account"), verbose_name=_("Name"))
    icon = models.CharField(
        max_length=64, default="building-columns", verbose_name=_("Icon")
    )

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return reverse("account", kwargs={"pk": self.pk})

    def get_delete_url(self):
        return reverse("del_account", kwargs={"pk": self.pk})

    @property
    def transactions(self):
        return Transaction.objects.filter(account=self)

    @property
    def snapshots(self):
        return Snapshot.objects.filter(account=self)

    class Meta:
        ordering = ["name"]
        verbose_name = _("Account")
        verbose_name_plural = _("Accounts")


class AccountModel(CustomModel):
    account = models.ForeignKey(
        Account,
        on_delete=models.CASCADE,
        verbose_name=_("Account"),
    )

    class Meta:
        abstract = True


class Category(CustomModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(
        max_length=64, default=_("Category"), verbose_name=_("Name")
    )
    icon = models.CharField(max_length=64, default="folder", verbose_name=_("Icon"))
    budget = models.BooleanField(default=True, verbose_name=_("Budget"))

    def __str__(self):
        return self.name

    def get_absolute_url(self):
        return reverse("category", kwargs={"pk": self.pk})

    def get_delete_url(self):
        return reverse("del_category", kwargs={"pk": self.pk})

    @property
    def transactions(self):
        return Transaction.objects.filter(category=self)

    class Meta:
        ordering = ["name"]
        verbose_name = _("Category")
        verbose_name_plural = _("Categories")


def snapshot_path(instance, filename):
    return pathlib.Path("snapshots", str(instance.id)).with_suffix(".pdf")


class Snapshot(AccountModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    date = models.DateField(default=datetime.date.today, verbose_name=_("End date"))
    start_date = models.DateField(
        default=datetime.date.today, verbose_name=_("Start date")
    )
    value = models.DecimalField(
        max_digits=12, decimal_places=2, default=0, verbose_name=_("End value")
    )
    start_value = models.DecimalField(
        max_digits=12, decimal_places=2, default=0, verbose_name=_("Start value")
    )
    diff = models.DecimalField(
        max_digits=12,
        decimal_places=2,
        default=0,
        verbose_name=_("Difference"),
        editable=False,
    )
    sum = models.DecimalField(
        max_digits=12,
        decimal_places=2,
        default=0,
        verbose_name=_("Transaction difference"),
        editable=False,
    )
    file = models.FileField(
        upload_to=snapshot_path,
        validators=[FileExtensionValidator(["pdf"])],
        verbose_name=_("File"),
        max_length=256,
        blank=True,
        default="",
    )

    def __str__(self):
        return _("%(date)s statement") % {"date": self.date}

    def save(self, *args, **kwargs):
        if Snapshot.objects.filter(id=self.id).exists():
            _prever = Snapshot.objects.get(id=self.id)
            if _prever.file and _prever.file != self.file:
                pathlib.Path(_prever.file.path).unlink(missing_ok=True)

        with transaction.atomic():
            for trans in self.transaction_set.all():
                trans.save()

        self.diff = self.value - self.start_value
        super().save(*args, **kwargs)

    def update_sum(self):
        self.sum = self.transaction_set.aggregate(sum=models.Sum("value")).get("sum", 0)
        super().save()

    def delete(self, *args, only_super=False, **kwargs):
        if self.file:
            self.file.delete()

    def get_absolute_url(self):
        return reverse("snapshot", kwargs={"pk": self.pk})

    def get_delete_url(self):
        return reverse("del_snapshot", kwargs={"pk": self.pk})

    class Meta:
        ordering = ["-date"]
        verbose_name = _("Statement")
        verbose_name_plural = _("Statements")


class Transaction(CustomModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(
        max_length=256, default=_("Transaction"), verbose_name=_("Name")
    )
    description = models.TextField(null=True, blank=True, verbose_name=_("Description"))
    value = models.DecimalField(
        max_digits=12, decimal_places=2, default=0, verbose_name=_("Value")
    )
    date = models.DateField(default=datetime.date.today, verbose_name=_("Date"))
    real_date = models.DateField(blank=True, null=True, verbose_name=_("Real date"))
    trader = models.CharField(
        max_length=128, blank=True, null=True, verbose_name=_("Trader")
    )
    payment = models.CharField(
        max_length=128, blank=True, null=True, verbose_name=_("Payment")
    )
    category = models.ForeignKey(
        Category,
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
        verbose_name=_("Category"),
    )
    snapshot = models.ForeignKey(
        Snapshot,
        on_delete=models.CASCADE,
        verbose_name=_("Statement"),
    )
    account = models.ForeignKey(
        Account,
        on_delete=models.CASCADE,
        verbose_name=_("Account"),
        editable=False,
    )

    def save(self, *args, **kwargs):
        self.account = self.snapshot.account
        super().save(*args, **kwargs)
        self.snapshot.update_sum()

    def __str__(self):
        return f"{self.date} – {self.name}"

    def get_absolute_url(self):
        return reverse("transaction", kwargs={"pk": self.pk})

    def get_delete_url(self):
        return reverse("del_transaction", kwargs={"pk": self.pk})

    @property
    def invoices(self):
        return Invoice.objects.filter(transaction=self)

    @property
    def has_invoice(self):
        return self.invoices.count() > 0

    class Meta:
        ordering = ["-date"]
        verbose_name = _("Transaction")
        verbose_name_plural = _("Transactions")


def invoice_path(instance, filename):
    return pathlib.Path("invoices", str(instance.id)).with_suffix(".pdf")


class Invoice(CustomModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(
        max_length=256, default=_("Invoice"), verbose_name=_("Name")
    )
    file = models.FileField(
        upload_to=invoice_path,
        validators=[FileExtensionValidator(["pdf"])],
        verbose_name=_("File"),
        max_length=128,
    )
    transaction = models.ForeignKey(
        Transaction, on_delete=models.CASCADE, editable=False
    )

    def __str__(self):
        if hasattr(self, "transaction"):
            return f"{self.name} – {self.transaction.name}"
        return self.name

    def delete(self, *args, **kwargs):
        self.file.delete()
        super().delete(*args, **kwargs)

    def get_absolute_url(self):
        return reverse(
            "invoice", kwargs={"transaction_pk": self.transaction.pk, "pk": self.pk}
        )

    def get_delete_url(self):
        return reverse(
            "del_invoice", kwargs={"transaction_pk": self.transaction.pk, "pk": self.pk}
        )

    class Meta:
        verbose_name = _("Invoice")
        verbose_name_plural = _("Invoices")