"""
세션·메시지 미러 — 프론트 `features/snap/contract/types.ts` 와 1:1.

대화 원본(컨텍스트)은 OpenCode 가 들고 있고, 여긴 목록·검색·usage·isGenerating 용 사본.
OpenCode 는 페이지네이션·본문 검색·메시지별 토큰을 안 주니까 여기서 함.
"""

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


class ChatSession(models.Model):
    id = models.CharField(primary_key=True, max_length=64)  # OpenCode session id 그대로
    user = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name="chat_sessions")
    title = models.CharField(max_length=200, blank=True)  # 사용자가 지은 제목 (지금은 안 씀)
    title_llm = models.CharField(max_length=200, blank=True)  # OpenCode 가 지은 제목
    is_generating = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["-updated_at"]

    def as_dto(self) -> dict:
        return {
            "id": self.id,
            "title": self.title or None,
            "titleLlm": self.title_llm or None,
            "isGenerating": self.is_generating,
            "createdAt": self.created_at.isoformat(),
            "updatedAt": self.updated_at.isoformat(),
        }


class ChatMessage(models.Model):
    ROLES = [("user", "user"), ("assistant", "assistant"), ("system", "system")]

    session = models.ForeignKey(ChatSession, on_delete=models.CASCADE, related_name="messages")
    role = models.CharField(max_length=16, choices=ROLES)
    content = models.TextField()  # markdown
    created_at = models.DateTimeField(auto_now_add=True)
    # assistant 행에만 채움
    input_tokens = models.IntegerField(null=True, blank=True)
    output_tokens = models.IntegerField(null=True, blank=True)
    cost_usd = models.FloatField(null=True, blank=True)
    elapsed_ms = models.IntegerField(null=True, blank=True)

    class Meta:
        ordering = ["created_at", "id"]

    def as_dto(self) -> dict:
        return {
            "sessionId": self.session_id,
            "role": self.role,
            "content": self.content,
            "createdAt": self.created_at.isoformat(),
            "inputTokens": self.input_tokens,
            "outputTokens": self.output_tokens,
            "costUsd": self.cost_usd,
            "elapsedMs": self.elapsed_ms,
        }