from django.db import models
from core.apps.management.models import Device

class Expense(models.Model):
    class ExpenseType(models.TextChoices):
        RENT = "rent", "Ijara"
        SALARY = "salary", "Maosh"
        UTILITIES = "utilities", "Kommunal to‘lovlar"
        MAINTENANCE = "maintenance", "Texnik xizmat"
        FOOD = "food", "Oziq-ovqat"
        TRANSPORT = "transport", "Yo'lkira"
        BUY_TOYS = "buy_toys", "Oʻyinchoqlar sotib olish"
        OTHER = "other", "Boshqa"

    amount = models.DecimalField(max_digits=12, decimal_places=2)
    expense_type = models.CharField(
        max_length=20,
        choices=ExpenseType.choices,
        default=ExpenseType.OTHER,
    )

    # Conditional fields
    employee = models.ForeignKey("accounts.User", related_name="salaries", null=True, blank=True, on_delete=models.PROTECT)
    device = models.ForeignKey(Device, null=True, blank=True, on_delete=models.PROTECT)

    created_by = models.ForeignKey("accounts.User", on_delete=models.PROTECT)
    confirmed_by = models.ForeignKey(
        "accounts.User", on_delete=models.PROTECT,
        null=True, blank=True, related_name="confirmed_expenses"
    )

    is_confirmed = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)

    def clean(self):
        from django.core.exceptions import ValidationError

        # Salary requires employee
        if self.expense_type == self.ExpenseType.SALARY and not self.employee:
            raise ValidationError({"employee": "Employee must be set for Salary expenses."})

        # Device required for rent/utilities/maintenance
        if self.expense_type in [
            self.ExpenseType.RENT,
            self.ExpenseType.MAINTENANCE
        ] and not self.device:
            raise ValidationError({"device": "Device must be set for this type of expense."})