chat/backend/app/services/climate_service.py

"""聊天气候服务：把对话节奏翻译成季节/温度/天气"""

import json
from datetime import datetime, timedelta

from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.chat_climate import ChatClimate
from app.models.message import Message
from app.models.conversation_member import ConversationMember


SEASON_EMOJI = {
    "spring": "🌸", "summer": "☀️", "autumn": "🍁", "winter": "❄️",
}
WEATHER_EMOJI = {
    "sunny": "晴", "cloudy": "多云", "rainy": "雨", "windy": "风", "snowy": "雪",
}


class ClimateService:
    def __init__(self, db: AsyncSession):
        self.db = db

    async def _verify_member(self, conversation_id: str, user_id: str) -> bool:
        result = await self.db.execute(
            select(ConversationMember).where(
                ConversationMember.conversation_id == conversation_id,
                ConversationMember.user_id == user_id,
            )
        )
        return result.scalars().first() is not None

    async def compute(self, conversation_id: str, user_id: str) -> dict:
        """计算/更新会话气候"""
        if not await self._verify_member(conversation_id, user_id):
            raise ValueError("无权访问该会话")

        # 取近 14 天消息
        since = datetime.utcnow() - timedelta(days=14)
        result = await self.db.execute(
            select(Message).where(
                Message.conversation_id == conversation_id,
                Message.is_deleted == False,
                Message.created_at >= since,
            ).order_by(Message.created_at.asc())
        )
        msgs = result.scalars().all()

        season, temperature, weather = self._analyze(msgs)
        emoji = SEASON_EMOJI[season]

        # 更新气候记录
        cc_result = await self.db.execute(
            select(ChatClimate).where(ChatClimate.conversation_id == conversation_id)
        )
        climate = cc_result.scalars().first()

        # 日历历史
        history = []
        if climate and climate.daily_history:
            try:
                history = json.loads(climate.daily_history)
            except Exception:
                history = []

        today = datetime.utcnow().strftime("%Y-%m-%d")
        history = [h for h in history if h.get("date") != today]
        history.append({"date": today, "season": season, "temp": temperature, "emoji": emoji})
        history = history[-30:]  # 保留 30 天

        if climate:
            climate.season = season
            climate.temperature = temperature
            climate.weather = weather
            climate.emoji = emoji
            climate.daily_history = json.dumps(history, ensure_ascii=False)
        else:
            climate = ChatClimate(
                conversation_id=conversation_id,
                season=season, temperature=temperature, weather=weather,
                emoji=emoji, daily_history=json.dumps(history, ensure_ascii=False),
            )
            self.db.add(climate)
        await self.db.flush()

        return {
            "conversation_id": conversation_id,
            "season": season,
            "temperature": temperature,
            "weather": weather,
            "emoji": emoji,
            "weather_label": WEATHER_EMOJI[weather],
            "message_count_14d": len(msgs),
        }

    def _analyze(self, msgs: list[Message]) -> tuple[str, int, str]:
        """根据消息列表分析季节/温度/天气"""
        n = len(msgs)
        if n == 0:
            return "winter", -8, "snowy"

        # 14 天内的消息分布 → 温度（活跃度）
        # 温度 = 消息密度映射到 -10..40
        density = min(n / 14, 1)  # 平均每天消息数（封顶 1 表示满）
        temperature = round(-8 + density * 46)  # -8 .. 38

        # 季节：按温度分段
        if temperature >= 28:
            season = "summer"
        elif temperature >= 15:
            season = "spring"
        elif temperature >= 5:
            season = "autumn"
        else:
            season = "winter"

        # 天气：根据回复间隔/连续性 + 平均字数
        if n >= 2:
            gaps = []
            for i in range(1, n):
                gap = (msgs[i].created_at - msgs[i - 1].created_at).total_seconds()
                gaps.append(gap)
            avg_gap = sum(gaps) / len(gaps)
            avg_len = sum(len(m.content or "") for m in msgs) / n

            # 连续性（gap 小 = 连续）
            if avg_gap < 120:  # 2 分钟内，热烈
                weather = "sunny"
            elif avg_gap < 1800:  # 半小时内，正常
                weather = "cloudy"
            elif avg_gap < 21600:  # 6 小时内，稀疏
                weather = "rainy"
            elif avg_gap < 86400:  # 一天内
                weather = "windy"
            else:
                weather = "snowy"

            # 字数长 = 有深度对话，偏向"雨"（绵绵）
            if avg_len > 50 and weather in ("sunny", "cloudy"):
                weather = "rainy"
        else:
            weather = "cloudy"

        return season, temperature, weather

    async def get_calendar(self, conversation_id: str, user_id: str) -> list[dict]:
        """获取 30 天气候日历"""
        if not await self._verify_member(conversation_id, user_id):
            raise ValueError("无权访问该会话")
        result = await self.db.execute(
            select(ChatClimate).where(ChatClimate.conversation_id == conversation_id)
        )
        climate = result.scalars().first()
        if not climate or not climate.daily_history:
            return []
        try:
            return json.loads(climate.daily_history)
        except Exception:
            return []