import uuid

from django.conf import settings
from django.db import models


class GroupRole(models.TextChoices):
    ADMIN = "admin", "Admin"
    MEMBER = "member", "Member"


class JoinRequestStatus(models.TextChoices):
    PENDING = "pending", "Pending"
    APPROVED = "approved", "Approved"
    REJECTED = "rejected", "Rejected"


class Group(models.Model):
    name = models.CharField(max_length=256, db_index=True)
    description = models.TextField(blank=True, default="")
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="created_groups",
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        db_table = "groups_group"
        verbose_name = "Group"
        verbose_name_plural = "Groups"
        ordering = ["-created_at"]

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


class GroupMember(models.Model):
    group = models.ForeignKey(
        Group,
        on_delete=models.CASCADE,
        related_name="memberships",
    )
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="group_memberships",
    )
    role = models.CharField(
        max_length=16,
        choices=GroupRole.choices,
        default=GroupRole.MEMBER,
    )
    joined_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "groups_member"
        verbose_name = "Group Member"
        verbose_name_plural = "Group Members"
        ordering = ["joined_at"]
        unique_together = [("group", "user")]

    def __str__(self) -> str:
        return f"{self.user} in {self.group} ({self.role})"


class GroupInvite(models.Model):
    group = models.ForeignKey(
        Group,
        on_delete=models.CASCADE,
        related_name="invites",
    )
    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="created_invites",
    )
    code = models.UUIDField(default=uuid.uuid4, unique=True, editable=False, db_index=True)
    max_uses = models.PositiveIntegerField(default=0, help_text="0 = unlimited")
    use_count = models.PositiveIntegerField(default=0)
    is_active = models.BooleanField(default=True, db_index=True)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "groups_invite"
        verbose_name = "Group Invite"
        verbose_name_plural = "Group Invites"
        ordering = ["-created_at"]

    def __str__(self) -> str:
        return f"Invite for {self.group.name} ({self.code})"


class JoinRequest(models.Model):
    group = models.ForeignKey(
        Group,
        on_delete=models.CASCADE,
        related_name="join_requests",
    )
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name="join_requests",
    )
    invite = models.ForeignKey(
        GroupInvite,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name="join_requests",
    )
    status = models.CharField(
        max_length=16,
        choices=JoinRequestStatus.choices,
        default=JoinRequestStatus.PENDING,
        db_index=True,
    )
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        db_table = "groups_join_request"
        verbose_name = "Join Request"
        verbose_name_plural = "Join Requests"
        ordering = ["-created_at"]
        unique_together = [("group", "user")]

    def __str__(self) -> str:
        return f"{self.user} → {self.group.name} ({self.status})"