from django.conf import settings
from django.db import models
from django.utils import timezone
from django.utils.translation import gettext_lazy as _


class SupportRoom(models.Model):
    class StatusChoices(models.TextChoices):
        OPEN = 'open', _('Open')
        PENDING = 'pending', _('Pending Support Reply')
        ANSWERED = 'answered', _('Answered')
        CLOSED = 'closed', _('Closed')

    user = models.OneToOneField(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        related_name='support_room',
        verbose_name=_('User'),
    )
    status = models.CharField(
        max_length=20,
        choices=StatusChoices.choices,
        default=StatusChoices.OPEN,
        db_index=True,
        verbose_name=_('Status'),
    )
    assigned_to = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='assigned_support_rooms',
        verbose_name=_('Assigned Specialist'),
    )
    unread_by_admin = models.PositiveIntegerField(
        default=0,
        verbose_name=_('Unread by Admin'),
    )
    unread_by_user = models.PositiveIntegerField(
        default=0,
        verbose_name=_('Unread by User'),
    )
    last_message_at = models.DateTimeField(
        null=True,
        blank=True,
        db_index=True,
        verbose_name=_('Last Message At'),
    )
    created_at = models.DateTimeField(
        auto_now_add=True,
        verbose_name=_('Created At'),
    )
    updated_at = models.DateTimeField(
        auto_now=True,
        verbose_name=_('Updated At'),
    )

    class Meta:
        verbose_name = _('Support Room')
        verbose_name_plural = _('Support Rooms')
        ordering = ('-last_message_at', '-created_at')

    def __str__(self):
        user_label = self.user.email or self.user.fullname or f"Guest #{self.user_id}"
        return f"Support Room #{self.pk} - {user_label}"


class SupportMessage(models.Model):
    class SenderType(models.TextChoices):
        USER = 'user', _('User')
        SUPPORT = 'support', _('Support Specialist')

    room = models.ForeignKey(
        SupportRoom,
        on_delete=models.CASCADE,
        related_name='messages',
        verbose_name=_('Support Room'),
    )
    sender_type = models.CharField(
        max_length=16,
        choices=SenderType.choices,
        default=SenderType.USER,
        db_index=True,
        verbose_name=_('Sender Type'),
    )
    sender = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.SET_NULL,
        null=True,
        blank=True,
        related_name='sent_support_messages',
        verbose_name=_('Sender User'),
    )
    content = models.TextField(
        verbose_name=_('Message Content'),
    )
    is_read = models.BooleanField(
        default=False,
        db_index=True,
        verbose_name=_('Is Read'),
    )
    created_at = models.DateTimeField(
        auto_now_add=True,
        db_index=True,
        verbose_name=_('Created At'),
    )

    class Meta:
        verbose_name = _('Support Message')
        verbose_name_plural = _('Support Messages')
        ordering = ('id',)

    def __str__(self):
        return f"[{self.sender_type}] Room #{self.room_id}: {self.content[:40]}"

    def save(self, *args, **kwargs):
        is_new = self.pk is None
        super().save(*args, **kwargs)
        if is_new and self.room_id:
            now = self.created_at or timezone.now()
            if self.sender_type == self.SenderType.USER:
                SupportRoom.objects.filter(pk=self.room_id).update(
                    last_message_at=now,
                    status=SupportRoom.StatusChoices.PENDING,
                    unread_by_admin=models.F('unread_by_admin') + 1,
                    updated_at=now,
                )
            elif self.sender_type == self.SenderType.SUPPORT:
                SupportRoom.objects.filter(pk=self.room_id).update(
                    last_message_at=now,
                    status=SupportRoom.StatusChoices.ANSWERED,
                    unread_by_user=models.F('unread_by_user') + 1,
                    unread_by_admin=0,
                    updated_at=now,
                )
                SupportMessage.objects.filter(
                    room_id=self.room_id,
                    sender_type=self.SenderType.USER,
                    is_read=False,
                ).update(is_read=True)