from django.db import models
from django.db.models import F
from django.db.models.expressions import Window
from django.db.models.functions import Rank


class Version(models.Model):
    name = models.CharField(max_length=50, unique=True)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self) -> str:
        return self.name


class ScoreManager(models.Manager):
    def get_queryset(self) -> models.QuerySet["Score"]:
        return (
            super()
            .get_queryset()
            .select_related("version")
            .annotate(
                rank=Window(
                    expression=Rank(),
                    order_by=F("points").desc(),
                )
            )
        )


class Score(models.Model):
    username = models.CharField(max_length=100)
    points = models.IntegerField()
    version = models.ForeignKey(
        Version, on_delete=models.PROTECT, null=True, blank=True, related_name="scores"
    )
    created_at = models.DateTimeField(auto_now_add=True)

    objects = ScoreManager()

    class Meta:
        ordering = ["-points"]

    def __str__(self) -> str:
        return f"{self.username}: {self.points}"