第一次提交

backend/app/modules/auth/service.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+import jwt
+from datetime import datetime, timedelta, timezone
+
+from app.core.config import get_settings
+
+
+def _now() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+def create_access_token(user_id: str, expires_minutes: int | None = None) -> str:
+    """为指定用户签发 JWT 访问令牌。"""
+    settings = get_settings()
+    expire = _now() + timedelta(minutes=expires_minutes or settings.access_token_expire_minutes)
+    payload = {
+        "sub": user_id,
+        "iat": int(_now().timestamp()),
+        "exp": int(expire.timestamp()),
+    }
+    return jwt.encode(payload, settings.jwt_secret, algorithm=settings.jwt_algorithm)
+
+
+def decode_access_token(token: str) -> str | None:
+    """校验并返回令牌中的用户 ID；无效/过期返回 None。"""
+    settings = get_settings()
+    try:
+        payload = jwt.decode(token, settings.jwt_secret, algorithms=[settings.jwt_algorithm])
+    except jwt.PyJWTError:
+        return None
+    sub = payload.get("sub")
+    return sub if isinstance(sub, str) else None