from django.db import models
from django.contrib.auth.models import User, Group

from ..models.courses import Course
from ..models.aircrafts import Aircraft

class Student(models.Model):
    id = models.AutoField(
        primary_key=True
    )

    email = models.EmailField(
        null=False,
        db_index=True
    )

    phone = models.CharField(
        null=True,
        max_length=16
    )

    name = models.CharField(
        null=False,
        max_length=32
    )

    surname = models.CharField(
        null=False,
        max_length=32
    )

    course = models.ForeignKey(
        Course,
        on_delete=models.DO_NOTHING,
        null=True
    )

    active = models.BooleanField(
        null=False,
        default=True
    )

    user = models.OneToOneField(
        User, 
        on_delete=models.CASCADE, 
        null=True, 
        blank=True
    )

    aircrafts = models.ManyToManyField(
        Aircraft
    )

    def default_password(self) -> str:  # Maximum 4 digits for passowrd
        return f"{self.name.lower()[0]}{self.surname.lower()}{self.id % 10000}"
    
    def default_username(self) -> str:
        if self.pk and self.user:
            return self.user.username
        else:
            return ""

    # Override save method to add user for login upon Student creation
    def save(self, *args, **kwargs):
        creating: bool = self.pk is None
        super().save(*args, **kwargs)
        if creating and not self.user:
            username: str = f"{self.name.lower()}.{self.surname.lower()}"
            # Avoid username conflict with progressive number
            base_username = username
            counter: int = 1
            while User.objects.filter(username=username).exists():
                username = f"{base_username}{counter}"
                counter += 1
            # Create user
            user: User = User.objects.create_user(
                first_name=self.name,
                last_name=self.surname,
                username=username,
                email=self.email,
                password=self.default_password(),
                is_staff=True # allows access to admin page
            )

            student_group, _ = Group.objects.get_or_create(name="StudentGroup")
            user.groups.add(student_group)
            self.user = user
            self.save()

    def __str__(self):
        return f"{self.surname} {self.name[0]}. => {self.course}"