from django.db import models
from django.utils.translation import gettext_lazy as _

from apps.account.models import StudentUser, User
from apps.course.models import Course


class Participant(models.Model):
    student = models.ForeignKey(
        StudentUser,
        on_delete=models.CASCADE,
        related_name='participated_courses',
        verbose_name=_('Student')
    )
    course = models.ForeignKey(
        Course,
        on_delete=models.CASCADE,
        related_name='participants',
        verbose_name=_('Course')
    )
    is_active = models.BooleanField(default=True, verbose_name=_('Is Active'))
    joined_date = models.DateTimeField(auto_now_add=True, verbose_name=_('Joined Date'))
    unread_messages_count = models.IntegerField(default=0, verbose_name=_('Unread Messages Count'))
    
    class Meta:
        unique_together = ('student', 'course')
        verbose_name = _('Participant')
        verbose_name_plural = _('Participants')
        indexes = [
            models.Index(fields=['student']),
            models.Index(fields=['course']),
            models.Index(fields=['joined_date']),
            models.Index(fields=['student', 'course']),
        ]