from django.db import models
from django.shortcuts import get_object_or_404
from django.utils import timezone
from decimal import Decimal
from django.urls import reverse, reverse_lazy


class Classroom(models.Model):
    name = models.CharField(max_length=40, blank=True, null=True)

    def __str__(self):
        return self.name


class Student(models.Model):
    first_name = models.CharField(max_length=30, blank=True)
    last_name = models.CharField(max_length=30, blank=True)
    classroom = models.ForeignKey(Classroom,
                                  on_delete=models.DO_NOTHING, blank=True, null=True)
    tution_fee = models.DecimalField(decimal_places=2,
                                     max_digits=12, default=0)
    paid_all = models.BooleanField(default=False)
    active = models.BooleanField(default=True)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ('first_name',)

    def __str__(self):
        return self.full_name

    @property
    def full_name(self):
        "Returns the person's full name."
        return f'{self.first_name} {self.last_name}'

    @property
    def get_tuition_fee(self):
        return self.tution_fee

    @property
    def get_total_paid_fee(self):
        return sum(student.payment for student in self.student_fee.all())

    @property
    def get_remaining_fee(self):
        total_fee = self.get_tuition_fee
        total_paid = self.get_total_paid_fee
        return total_fee - total_paid


class StudentFee(models.Model):
    PaymentTypes = (
        ('monthly', 'Monthly'),
        ('quarterly', 'Quarterly'),
        ('yearly', 'Yearly'),
    )
    student = models.ForeignKey(Student, related_name='student_fee',
                                on_delete=models.CASCADE)
    payment_date = models.DateField(default=timezone.now)
    payment_type = models.CharField(max_length=10, choices=PaymentTypes)
    payment = models.DecimalField(decimal_places=2, max_digits=12)

    class Meta:
        ordering = ('-payment_date',)

    def get_absolute_url(self):
        return reverse_lazy('student_detail', kwargs={'pk': self.student_id})

    def save(self, *args, **kwargs):
        # save the studentfee record first before updating master table i.e. Student
        super().save(*args, **kwargs)

        # fee = self.student.get_remaining_fee()
        fee = self.student.get_remaining_fee
        try:
            student_instance = Student.objects.get(id=self.student_id)
            if fee <= 0:
                student_instance.paid_all = True
            else:
                student_instance.paid_all = False

            student_instance.save()

        except Exception as e:
            print(e)