chat/backend/app/services/sync_service.py

"""默契种子服务"""

import hashlib
import re
import uuid
from datetime import datetime

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

from app.models.sync_seed import SyncQuestion, SyncSeed
from app.models.friend import Friend
from app.models.user import User
from app.websocket.events import EventType
from app.websocket.manager import manager


# 预置题目池
DEFAULT_QUESTIONS = [
    "用一个词形容你理想中的周末",
    "深夜最想吃的一道食物",
    "如果有一整天完全自由，你会做什么",
    "最近让你开心的瞬间是什么",
    "你最向往的旅行目的地",
    "用一种颜色形容你现在的状态",
    "你的快乐源泉是什么",
    "如果会一种超能力，你想要什么",
]


def _tokenize(text: str) -> set[str]:
    """中文分词：按 2-gram + 标点切分；英文按单词"""
    if not text:
        return set()
    tokens = set()
    # 英文单词
    for w in re.findall(r'[a-zA-Z]+', text.lower()):
        if len(w) >= 2:
            tokens.add(w)
    # 中文 2-gram
    cn = re.sub(r'[^一-鿿]', '', text)
    for i in range(len(cn) - 1):
        tokens.add(cn[i:i + 2])
    # 单字
    for ch in cn:
        tokens.add(ch)
    return tokens


def _jaccard(a: set[str], b: set[str]) -> float:
    if not a or not b:
        return 0.0
    inter = len(a & b)
    union = len(a | b)
    return inter / union if union else 0.0


def _score_answers(a: str, b: str) -> int:
    """0-100 默契分：Jaccard 为主 + 句长相似 + emoji/标点加分"""
    if not a or not b:
        return 0
    ta, tb = _tokenize(a), _tokenize(b)
    j = _jaccard(ta, tb)
    # 句长相似度
    len_diff = abs(len(a) - len(b)) / max(len(a), len(b), 1)
    len_sim = 1 - len_diff
    # emoji / 相同标点
    emoji_a = set(re.findall(r'[\U0001F300-\U0001FAFF]', a))
    emoji_b = set(re.findall(r'[\U0001F300-\U0001FAFF]', b))
    emoji_bonus = 0.1 if emoji_a and emoji_a & emoji_b else 0
    raw = j * 0.7 + len_sim * 0.2 + emoji_bonus
    # 放大曲线：让中等重合也能有可见分数
    score = round(min(100, raw * 130 + (10 if j > 0 else 0)))
    return max(0, min(100, score))


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

    async def _ensure_questions(self):
        """确保题目池存在"""
        result = await self.db.execute(select(func.count(SyncQuestion.id)))
        if (result.scalar() or 0) == 0:
            for q in DEFAULT_QUESTIONS:
                self.db.add(SyncQuestion(id=str(uuid.uuid4()), content=q))
            await self.db.flush()

    async def get_today_question(self) -> dict:
        """获取今日题目（按日期确定性选取）"""
        await self._ensure_questions()
        result = await self.db.execute(select(SyncQuestion))
        questions = result.scalars().all()
        if not questions:
            raise ValueError("没有题目")
        today = datetime.utcnow().strftime("%Y%m%d")
        idx = int(hashlib.md5(today.encode()).hexdigest(), 16) % len(questions)
        q = questions[idx]
        return {"id": q.id, "content": q.content}

    async def _get_or_create_seed(self, question_id: str, user_a: str, user_b: str) -> SyncSeed:
        a, b = (user_a, user_b) if user_a < user_b else (user_b, user_a)
        result = await self.db.execute(
            select(SyncSeed).where(
                SyncSeed.question_id == question_id,
                SyncSeed.user_a == a,
                SyncSeed.user_b == b,
            )
        )
        seed = result.scalars().first()
        if not seed:
            seed = SyncSeed(
                id=str(uuid.uuid4()),
                question_id=question_id,
                user_a=a,
                user_b=b,
            )
            self.db.add(seed)
            await self.db.flush()
        return seed

    async def submit_answer(self, user_id: str, question_id: str, friend_id: str,
                            answer: str) -> dict:
        """提交自己的答案"""
        # 校验是好友
        fr = await self.db.execute(
            select(Friend).where(Friend.user_id == user_id, Friend.friend_user_id == friend_id)
        )
        if not fr.scalars().first():
            raise ValueError("只能和好友默契")

        seed = await self._get_or_create_seed(question_id, user_id, friend_id)
        # 写入自己的答案（a 或 b）
        if seed.user_a == user_id:
            seed.answer_a = answer
        else:
            seed.answer_b = answer

        result: dict = {
            "id": seed.id,
            "question_id": question_id,
            "my_answer": answer,
            "status": seed.status,
        }

        # 双方都答了 → 揭晓
        if seed.answer_a and seed.answer_b and seed.status == "draft":
            score = _score_answers(seed.answer_a, seed.answer_b)
            seed.score = score
            leaf = hashlib.md5(
                f"sync:{question_id}:{seed.user_a}:{seed.user_b}".encode()
            ).hexdigest()[:16]
            seed.leaf_seed = leaf
            seed.status = "revealed"
            seed.revealed_at = datetime.utcnow()
            result["score"] = score
            result["leaf_seed"] = leaf
            result["partner_answer"] = seed.answer_b if seed.user_a == user_id else seed.answer_a
            # 推送给搭档
            await manager.send_to_user(friend_id, "sync.revealed", {
                "seed_id": seed.id,
                "question_id": question_id,
                "score": score,
                "leaf_seed": leaf,
            })

        await self.db.flush()
        return result

    async def get_seed(self, user_id: str, seed_id: str) -> dict:
        result = await self.db.execute(select(SyncSeed).where(SyncSeed.id == seed_id))
        seed = result.scalars().first()
        if not seed:
            raise ValueError("种子不存在")
        if user_id not in (seed.user_a, seed.user_b):
            raise ValueError("无权查看")

        my_answer = seed.answer_a if seed.user_a == user_id else seed.answer_b
        partner_answer = None
        if seed.status == "revealed":
            partner_answer = seed.answer_b if seed.user_a == user_id else seed.answer_a

        return {
            "id": seed.id,
            "question_id": seed.question_id,
            "my_answer": my_answer,
            "partner_answer": partner_answer,
            "score": seed.score,
            "leaf_seed": seed.leaf_seed,
            "status": seed.status,
        }