from django.contrib.auth import get_user_model
from django.db import models


class LockerBank(models.Model):
    name = models.CharField(max_length=200)
    location = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)
    rows = models.PositiveIntegerField()
    columns = models.PositiveIntegerField()
    # TODO: add constraint for unique first letter?

    def __str__(self):
        return f"{self.name} ({self.columns}x{self.rows})"

    @property
    def initial(self):
        return self.name[0].upper()

    @property
    def iter_doors(self):
        for row in range(self.rows):
            for column in range(self.columns):
                # TODO: filter could be optimized
                yield chr(row + ord("A")), column + 1, self.rentals.filter(
                    row=row, column=column
                )


class LockerRental(models.Model):
    locker_bank = models.ForeignKey(
        LockerBank, on_delete=models.CASCADE, related_name="rentals"
    )
    user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
    row = models.PositiveIntegerField()
    column = models.PositiveIntegerField()
    # TODO: add check constraint to ensure that row and column are within locker_bank bounds
    # TODO: add unique constraint on (bank, row, column)?

    @property
    def address(self) -> str:
        return f"{self.locker_bank.name}-{self.locker_bank.initial}{chr(self.row + ord('A'))}{self.column}"

    def __str__(self):
        return f"{self.user}: {self.address}"