add models

timetable/models.py

@@ -1 +1,82 @@
 # Create your models here.
+from datetime import timedelta
+
+from django.core.validators import MaxValueValidator, RegexValidator
+from django.db import models
+from django.db.models import F, Q
+from django.utils.translation import gettext_lazy as _
+
+from core.models import User
+from core.utils import get_semester_code
+
+
+class Timetable(models.Model):
+    user = models.ForeignKey(User, verbose_name=_("user"), on_delete=models.CASCADE)
+    semester = models.CharField(
+        _("semester"),
+        default=get_semester_code,
+        validators=[RegexValidator(r"(A|P)\d{2}")],
+        blank=True,
+    )
+
+    class Meta:
+        verbose_name = _("timetable")
+        verbose_name_plural = _("timetables")
+        constraints = [
+            models.UniqueConstraint(
+                fields=("user", "semester"), name="timetable_unique_user_semester"
+            )
+        ]
+        permissions = [("add_self_timetable", "Can add its own timetable")]
+
+    def __str__(self) -> str:
+        return f"{self.user} {self.semester}"
+
+
+class TimetableSlot(models.Model):
+    MINUTES_PER_SLOT = 15
+
+    class WeekDay(models.IntegerChoices):
+        MONDAY = 1
+        TUESDAY = 2
+        WEDNESDAY = 3
+        THURSDAY = 4
+        FRIDAY = 5
+        SATURDAY = 6
+        SUNDAY = 7
+
+    timetable = models.ForeignKey(
+        Timetable,
+        verbose_name=_("timetable"),
+        related_name="slots",
+        on_delete=models.CASCADE,
+    )
+    weekday = models.SmallIntegerField(_("weekday"), choices=WeekDay)
+    # there are 4 * 24 = 96 quarters in a day, and we start counting at 0
+    start_at = models.PositiveSmallIntegerField(
+        _("start at"), validators=[MaxValueValidator(95)]
+    )
+    end_at = models.PositiveSmallIntegerField(
+        _("end at"), validators=[MaxValueValidator(95)]
+    )
+
+    class Meta:
+        verbose_name = _("timetable slot")
+        verbose_name_plural = _("timetable slots")
+        constraints = [
+            models.CheckConstraint(
+                condition=Q(end_at__gt=F("start_at")),
+                name="timetable_slot_end_after_start",
+            )
+        ]
+
+    def __str__(self) -> str:
+        return f"{self.start_hour} - {self.end_hour} - {self.get_weekday_display()}"
+
+    @property
+    def start_hour(self):
+        return timedelta(minutes=self.start_at * self.MINUTES_PER_SLOT)
+
+    @property
+    def end_hour(self):
+        return timedelta(minutes=self.end_at * self.MINUTES_PER_SLOT)