class Project(models.Model):
    """Project entity representing a paid project for a customer."""
    name = models.CharField(max_length=200, db_index=True)
    customer = models.ForeignKey(Customer, on_delete=models.PROTECT)
    active = models.BooleanField(default=True)
    code = models.CharField(max_length=200, db_index=True, blank=True, null=False, editable=False)

    created_on = models.DateTimeField(auto_now_add=True)
    updated_on = models.DateTimeField(auto_now=True)

    def get_code_default(self) -> str:
        return f"P{self.customer.id}-{self.id}"

    # Override save function to populate self.code
    # We need to double save, because code is derived from pk but pk is None until object is saved
    def save(self, *args, **kwargs):
        created = not self.pk

        if created:
            # if initial creation, save instance to generate pk
            super().save(*args, **kwargs)

            # if instance doesn't have `code` generate it
        if not self.code:
            self.code = self.get_code_default()

        # save, saved in any case
        return super().save(*args, **kwargs)

    def __str__(self):
        return f"{self.customer.name} - {self.name} ({self.code})"


class ProjectCode(models.Model):
    name = models.CharField(max_length=200, db_index=True)
    code = models.CharField(max_length=200, unique=True, db_index=True, blank=True, null=False, editable=False)
    project = models.ForeignKey(Project, on_delete=models.PROTECT)
    active = models.BooleanField(default=True)
    rate = models.DecimalField(blank=True, null=True, max_digits=10, decimal_places=2)
    max_hours = models.IntegerField(blank=True, null=True)
    date_start = models.DateField(blank=True, null=True)
    date_end = models.DateField(blank=True, null=True)

    created_on = models.DateTimeField(auto_now_add=True)
    updated_on = models.DateTimeField(auto_now=True)

    def get_code_default(self) -> str:
        return f"PC-{self.project.customer.id}-{self.project.id}-{self.id}"

    # Override save function to populate self.code
    # We need to double save, because code is derived from pk but pk is None until object is saved
    def save(self, *args, **kwargs):
        created = not self.pk

        if created:
            # if initial creation, save instance to generate pk
            super().save(*args, **kwargs)

            # if instance doesn't have `code` generate it
        if not self.code:
            self.code = self.get_code_default()

        # save, saved in any case
        return super().save(*args, **kwargs)