from django.core.exceptions import ValidationError
from django.db import models
from django.db.models import Q
import datetime
from core.models.base import BaseModel
from core.models.account import AccountAddress

class Labor(BaseModel):
    """Labor records for accounts"""
    account_address = models.ForeignKey(
        AccountAddress,
        on_delete=models.PROTECT,
        related_name='labors',
        verbose_name="Account Service Address",
        null=True
    )
    amount = models.DecimalField(max_digits=10, decimal_places=2)
    start_date = models.DateField()
    end_date = models.DateField(blank=True, null=True)

    class Meta:
        ordering = ['-start_date']
        indexes = [
            models.Index(fields=['account_address', 'start_date']),
        ]
        verbose_name = "Labor"
        verbose_name_plural = "Labors"

    def __str__(self):
        return f"{self.account_address.account.name} - {self.account_address.name} - ${self.amount}"

    def clean(self):
        super().clean()

        # Basic date validity
        if self.end_date and self.start_date > self.end_date:
            raise ValidationError({'end_date': "End date must be after start date"})

        # Optional: amount validation
        if self.amount is None or self.amount < 0:
            raise ValidationError({'amount': "Amount must be a non-negative value"})

        # Overlap prevention within the same account_address
        start = self.start_date
        end = self.end_date or datetime.date.max

        qs = Labor.objects.filter(account_address=self.account_address)
        if self.pk:
            qs = qs.exclude(pk=self.pk)

        overlaps = qs.filter(
            Q(end_date__isnull=True, start_date__lte=end) |
            Q(end_date__isnull=False, start_date__lte=end, end_date__gte=start)
        )

        if overlaps.exists():
            raise ValidationError("Labor rate dates overlap with an existing labor rate for this address.")