# apps/chat/models.py
from django.db import models
from django.utils import timezone
import uuid
from itertools import count
from apps.user.models import User

class ChatHistory(models.Model):
    """聊天历史记录"""
    ROLE_CHOICES = [
        ('user', '用户'),
        ('assistant', 'AI助手'),
        ('system', '系统')
    ]

    user = models.ForeignKey(User, on_delete=models.CASCADE)
    # 改为使用字符串字段而非外键关联
    knowledge_base_id = models.CharField(max_length=100, default="b680a4fa-37be-11f0-a7cb-0242ac120002", help_text="知识库ID，用于兼容原有结构")
    # 用于标识知识库组合的对话
    conversation_id = models.CharField(max_length=100, db_index=True)
    # 对话标题
    title = models.CharField(max_length=100, null=True, blank=True, default='New chat', help_text="对话标题")
    parent_id = models.CharField(max_length=100, null=True, blank=True)
    role = models.CharField(max_length=20, choices=ROLE_CHOICES)
    content = models.TextField()
    tokens = models.IntegerField(default=0, help_text="消息token数")
    # 扩展metadata字段
    metadata = models.JSONField(default=dict, blank=True, help_text="存储额外信息")
    created_at = models.DateTimeField(auto_now_add=True)
    is_deleted = models.BooleanField(default=False)

    class Meta:
        ordering = ['created_at']
        indexes = [
            models.Index(fields=['conversation_id', 'created_at']),
            models.Index(fields=['user', 'created_at']),
            models.Index(fields=['conversation_id', 'is_deleted']),
        ]

    def __str__(self):
        return f"{self.user.email} - {self.title} - {self.created_at}"

    @classmethod
    def get_conversation(cls, conversation_id):
        """获取完整对话历史"""
        return cls.objects.filter(
            conversation_id=conversation_id,
            is_deleted=False
        ).order_by('created_at')

    @classmethod
    def get_conversations_by_user(cls, user):
        """根据用户获取对话历史"""
        return cls.objects.filter(
            user=user,
            is_deleted=False
        ).order_by('created_at')

    def soft_delete(self):
        """软删除消息"""
        self.is_deleted = True
        self.save()

    def to_dict(self):
        """转换为字典格式"""
        return {
            'id': str(self.id),
            'conversation_id': self.conversation_id,
            'role': self.role,
            'content': self.content,
            'created_at': self.created_at.strftime('%Y-%m-%d %H:%M:%S'),
            'metadata': self.metadata
        }