1.7

backend/app/services/echo_service.py

@@ -0,0 +1,97 @@
+"""念念回音服务"""
+
+import hashlib
+import uuid
+from datetime import datetime
+
+from sqlalchemy import select, or_
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.miss_echo import MissEcho
+from app.models.user import User
+from app.websocket.events import EventType
+from app.websocket.manager import manager
+
+
+class EchoService:
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def send_echo(self, from_user_id: str, to_user_id: str,
+                        message: str | None = None) -> dict:
+        """发送一片回音叶"""
+        if from_user_id == to_user_id:
+            raise ValueError("不能给自己回音")
+
+        # 校验目标用户存在
+        target_result = await self.db.execute(select(User).where(User.id == to_user_id))
+        if not target_result.scalars().first():
+            raise ValueError("目标用户不存在")
+
+        # 派生叶子种子
+        today = datetime.utcnow().strftime("%Y%m%d")
+        seed = hashlib.md5(f"echo:{from_user_id}:{to_user_id}:{today}".encode()).hexdigest()[:16]
+
+        is_online = manager.is_online(to_user_id)
+
+        echo = MissEcho(
+            id=str(uuid.uuid4()),
+            from_user_id=from_user_id,
+            to_user_id=to_user_id,
+            leaf_seed=seed,
+            message=message,
+            delivered_online=is_online,
+        )
+        self.db.add(echo)
+        await self.db.flush()
+
+        # 发送者信息
+        from_result = await self.db.execute(select(User).where(User.id == from_user_id))
+        from_user = from_result.scalars().first()
+
+        payload = {
+            "id": echo.id,
+            "from_user_id": from_user_id,
+            "from_username": from_user.username if from_user else "未知",
+            "from_nickname": from_user.nickname if from_user else None,
+            "from_avatar": from_user.avatar_url if from_user else None,
+            "leaf_seed": seed,
+            "message": message,
+            "delivered_online": is_online,
+            "created_at": echo.created_at.isoformat(),
+        }
+
+        # 在线则实时推送，离线则在用户下次打开时收到（落入花园）
+        if is_online:
+            await manager.send_to_user(to_user_id, EventType.ECHO_SEND, payload)
+
+        return payload
+
+    async def get_echoes(self, user_id: str, limit: int = 30) -> list[dict]:
+        """获取我收到的回音（花园里飘落的叶子）"""
+        result = await self.db.execute(
+            select(MissEcho).where(
+                or_(
+                    MissEcho.to_user_id == user_id,
+                    MissEcho.from_user_id == user_id,
+                )
+            ).order_by(MissEcho.created_at.desc()).limit(limit)
+        )
+        echoes = []
+        for e in result.scalars().all():
+            from_result = await self.db.execute(select(User).where(User.id == e.from_user_id))
+            fu = from_result.scalars().first()
+            echoes.append({
+                "id": e.id,
+                "from_user_id": e.from_user_id,
+                "to_user_id": e.to_user_id,
+                "from_username": fu.username if fu else "未知",
+                "from_nickname": fu.nickname if fu else None,
+                "from_avatar": fu.avatar_url if fu else None,
+                "leaf_seed": e.leaf_seed,
+                "message": e.message,
+                "delivered_online": e.delivered_online,
+                "is_received": e.to_user_id == user_id,
+                "created_at": e.created_at.isoformat(),
+            })
+        return echoes