from datetime import date
import uuid
from django.db import models
from django.forms import ModelForm
from django.core.validators import validate_unicode_slug, FileExtensionValidator


class Category(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(
        max_length=64, validators=[validate_unicode_slug], default="New Category"
    )
    icon = models.CharField(max_length=64, default="folder")

    def __str__(self):
        return self.name

    class Meta:
        ordering = ["name"]


class CategoryForm(ModelForm):
    class Meta:
        model = Category
        fields = ["name", "icon"]


class Transaction(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=256, default="New Transaction")
    description = models.TextField(null=True, blank=True)
    value = models.DecimalField(max_digits=12, decimal_places=2, default=0)
    date = models.DateField(default=date.today)
    trader = models.CharField(max_length=128, blank=True, null=True)
    category = models.ForeignKey(
        Category, on_delete=models.SET_NULL, blank=True, null=True
    )

    def __str__(self):
        res = f"{self.date} {self.name}: {self.value}€"
        if self.category:
            return f"{res} ({self.category})"
        return res

    class Meta:
        ordering = ["-date"]


class TransactionForm(ModelForm):
    class Meta:
        model = Transaction
        fields = ["date", "name", "value", "trader", "category", "description"]


class Invoice(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    name = models.CharField(max_length=256, default="New Invoice")
    file = models.FileField(
        upload_to="invoices/", validators=[FileExtensionValidator(["pdf"])]
    )
    transaction = models.ForeignKey(Transaction, on_delete=models.CASCADE)

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

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


class InvoiceForm(ModelForm):
    class Meta:
        model = Invoice
        fields = ["name", "file"]


class Snapshot(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    date = models.DateField(default=date.today, unique=True)
    value = models.DecimalField(max_digits=12, decimal_places=2, default=0)
    previous = models.OneToOneField(
        "self", on_delete=models.SET_NULL, blank=True, null=True, editable=False
    )
    diff = models.DecimalField(
        max_digits=12, decimal_places=2, default=0, editable=False
    )

    def __str__(self):
        if self.previous is None:
            return f"Snapshot {self.date}: {self.value}€"
        return f"Snapshot {self.date}: {self.value}€ (Previous: {self.previous.date})"

    def save(self, *args, only_super=False, **kwargs):
        if not only_super:
            _prev = (
                self.__class__.objects.order_by("-date")
                .exclude(id=self.id)
                .filter(date__lt=self.date)
                .first()
            )
            print(_prev)

            try:
                _next = self.__class__.objects.exclude(id=self.id).get(previous=_prev)
            except self.__class__.DoesNotExist:
                pass
            else:
                _next.previous = self
                _next.save(only_super=True)

            self.previous = _prev

        if self.previous is None:
            self.diff = 0
        else:
            self.diff = self.value - self.previous.value
        super().save(*args, **kwargs)

    def delete(self, *args, only_super=False, **kwargs):
        if not only_super:
            try:
                _next = self.__class__.objects.get(previous=self)
            except self.__class__.DoesNotExist:
                super().delete(*args, **kwargs)
            else:
                _next.previous = self.previous
                super().delete(*args, **kwargs)
                _next.save(only_super=True)
        else:
            super().delete(*args, **kwargs)

    @property
    def sum(self):
        if self.previous is None:
            return None
        trans = Transaction.objects.filter(
            date__lt=self.date, date__gte=self.previous.date
        ).aggregate(sum=models.Sum("value"))
        return trans["sum"] or 0

    class Meta:
        ordering = ["-date"]


class SnapshotForm(ModelForm):
    class Meta:
        model = Snapshot
        fields = ["date", "value"]