import uuid
from django.contrib.gis.db import models
from django.conf import settings


class Challenge(models.Model):
    class Status(models.TextChoices):
        ACTIVE = "active", "Active"
        CLOSED = "closed", "Closed"

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    creator = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="created_challenges"
    )

    title = models.CharField(max_length=255)
    description = models.TextField(blank=True, default="")
    status = models.CharField(max_length=20, choices=Status.choices, default=Status.ACTIVE, db_index=True)

    # The polygon users must be physically inside to submit a recording.
    # Drawn by the creator on the Cesium map.
    region = models.PolygonField(geography=True)
    # Derived centroid — stored separately for cheap proximity queries and map pin placement.
    # Set automatically from `region` on save; not user-supplied.
    region_centroid = models.PointField(geography=True)

    # Optional cap on accepted submissions (null = unlimited)
    max_submissions = models.PositiveIntegerField(null=True, blank=True)
    # Denormalised count of published splats linked to this challenge.
    # Incremented by a Celery task when a splat transitions to is_published=True.
    # Avoids a COUNT(*) on every map tile request.
    submission_count = models.PositiveIntegerField(default=0)

    expires_at = models.DateTimeField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def save(self, *args, **kwargs):
        # Keep centroid in sync with region automatically
        if self.region:
            self.region_centroid = self.region.centroid
        super().save(*args, **kwargs)

    def __str__(self):
        return self.title

    class Meta:
        db_table = "challenges"
        indexes = [
            models.Index(fields=["status", "created_at"]),
        ]


class ChallengeParticipant(models.Model):
    """
    A user who has bookmarked / accepted a challenge.
    Used to target FCM notifications (e.g. new submission, challenge expiring soon).
    Participation is recorded automatically when a user submits a splat for a challenge,
    or manually when they tap "I'll do this" in the app.
    """

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    challenge = models.ForeignKey(Challenge, on_delete=models.CASCADE, related_name="participants")
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="challenge_participations"
    )
    # The splat this user submitted for the challenge, if any
    submitted_splat = models.OneToOneField(
        "splats.Splat",
        null=True,
        blank=True,
        on_delete=models.SET_NULL,
        related_name="challenge_participation",
    )
    joined_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f"{self.user_id} → {self.challenge_id}"

    class Meta:
        db_table = "challenge_participants"
        unique_together = [("challenge", "user")]
        indexes = [
            models.Index(fields=["user", "joined_at"]),
        ]