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


class NotificationPreference(models.Model):
    user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='notification_preferences')
    order_updates = models.BooleanField(default=True)
    promotions = models.BooleanField(default=True)
    newsletter = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    def __str__(self):
        return f"{self.user.email} Notification Preferences"


class Conversation(models.Model):
    created_by = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='conversations_created')
    is_group = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    last_message_at = models.DateTimeField(null=True, blank=True)
    last_message_preview = models.CharField(max_length=300, blank=True)
    class Meta:
        ordering = ['-created_at']
        indexes = [
            models.Index(fields=['-created_at']),
            models.Index(fields=['last_message_at']),
        ]
    def __str__(self):
        return f"Conversation {self.id}"


class ConversationParticipant(models.Model):
    conversation = models.ForeignKey(Conversation, on_delete=models.CASCADE, related_name='participants')
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_memberships')
    joined_at = models.DateTimeField(auto_now_add=True)
    last_read_at = models.DateTimeField(null=True, blank=True)
    class Meta:
        unique_together = ('conversation', 'user')
        indexes = [
            models.Index(fields=['conversation', 'user']),
        ]
    def __str__(self):
        return f"{self.user_id} in {self.conversation_id}"


class Message(models.Model):
    conversation = models.ForeignKey(Conversation, on_delete=models.CASCADE, related_name='messages')
    sender = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_messages_sent')
    body = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)
    edited_at = models.DateTimeField(null=True, blank=True)
    is_deleted = models.BooleanField(default=False)
    class Meta:
        ordering = ['created_at']
        indexes = [
            models.Index(fields=['conversation', 'created_at']),
            models.Index(fields=['sender', '-created_at']),
        ]
    def __str__(self):
        return f"Msg {self.id} by {self.sender_id} in {self.conversation_id}"
    def save(self, *args, **kwargs):
        super().save(*args, **kwargs)
        try:
            preview = (self.body or '')[:300]
            self.conversation.last_message_at = self.created_at
            self.conversation.last_message_preview = preview
            self.conversation.save(update_fields=['last_message_at', 'last_message_preview'])
        except Exception:
            pass


def upload_chat_attachment(instance, filename):
    return f"chat_attachments/{filename}"


class MessageAttachment(models.Model):
    message = models.ForeignKey(Message, on_delete=models.CASCADE, related_name='attachments')
    file = models.FileField(upload_to=upload_chat_attachment)
    file_name = models.CharField(max_length=255, blank=True)
    content_type = models.CharField(max_length=100, blank=True)
    size = models.IntegerField(default=0)
    created_at = models.DateTimeField(auto_now_add=True)
    class Meta:
        ordering = ['created_at']
        indexes = [
            models.Index(fields=['message']),
        ]
    def __str__(self):
        return f"Attachment {self.id} for {self.message_id}"