初始化提交

backend/app/repositories/chat.py

@@ -0,0 +1,200 @@
+"""聊天数据访问。"""
+
+from sqlalchemy import func, select, update
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.errors import AppError
+from app.models.chat import ChatMessage, ChatSession
+
+
+async def get_session(
+    session: AsyncSession, session_id: str, *, owner_scope: str | None = None
+) -> ChatSession | None:
+    stmt = select(ChatSession).where(ChatSession.id == session_id)
+    if owner_scope is not None:
+        stmt = stmt.where(ChatSession.owner_scope == owner_scope)
+    result = await session.execute(stmt)
+    return result.scalar_one_or_none()
+
+
+async def list_recent_messages(
+    session: AsyncSession, session_id: str, *, limit: int = 12
+) -> list[ChatMessage]:
+    result = await session.execute(
+        select(ChatMessage)
+        .where(ChatMessage.session_id == session_id, ChatMessage.deleted_at.is_(None))
+        .order_by(ChatMessage.created_at.desc())
+        .limit(limit)
+    )
+    return list(reversed(result.scalars().all()))
+
+
+async def list_sessions(
+    session: AsyncSession,
+    character_id: str,
+    *,
+    status: str | None = None,
+    owner_scope: str | None = None,
+    limit: int = 50,
+    offset: int = 0,
+) -> list[ChatSession]:
+    conditions = [ChatSession.character_id == character_id, ChatSession.status != "deleted"]
+    if status is not None:
+        conditions.append(ChatSession.status == status)
+    if owner_scope is not None:
+        conditions.append(ChatSession.owner_scope == owner_scope)
+    result = await session.execute(
+        select(ChatSession)
+        .where(*conditions)
+        .order_by(ChatSession.updated_at.desc())
+        .offset(offset)
+        .limit(limit)
+    )
+    return list(result.scalars().all())
+
+
+async def count_sessions(
+    session: AsyncSession,
+    character_id: str,
+    *,
+    status: str | None = None,
+    owner_scope: str | None = None,
+) -> int:
+    conditions = [ChatSession.character_id == character_id, ChatSession.status != "deleted"]
+    if status is not None:
+        conditions.append(ChatSession.status == status)
+    if owner_scope is not None:
+        conditions.append(ChatSession.owner_scope == owner_scope)
+    result = await session.execute(select(func.count()).select_from(ChatSession).where(*conditions))
+    return result.scalar_one()
+
+
+async def list_messages(
+    session: AsyncSession, session_id: str, *, limit: int = 100, offset: int = 0
+) -> list[ChatMessage]:
+    result = await session.execute(
+        select(ChatMessage)
+        .where(ChatMessage.session_id == session_id, ChatMessage.deleted_at.is_(None))
+        .order_by(ChatMessage.created_at.asc())
+        .offset(offset)
+        .limit(limit)
+    )
+    return list(result.scalars().all())
+
+
+async def count_messages(session: AsyncSession, session_id: str) -> int:
+    result = await session.execute(
+        select(func.count())
+        .select_from(ChatMessage)
+        .where(
+            ChatMessage.session_id == session_id,
+            ChatMessage.deleted_at.is_(None),
+        )
+    )
+    return result.scalar_one()
+
+
+async def count_messages_by_sessions(
+    session: AsyncSession, session_ids: list[str]
+) -> dict[str, int]:
+    """批量统计多个会话的未删除消息数（GROUP BY 聚合，避免列表查询 N+1）。"""
+    if not session_ids:
+        return {}
+    result = await session.execute(
+        select(ChatMessage.session_id, func.count())
+        .where(
+            ChatMessage.session_id.in_(session_ids),
+            ChatMessage.deleted_at.is_(None),
+        )
+        .group_by(ChatMessage.session_id)
+    )
+    return {str(sid): int(cnt) for sid, cnt in result.all()}
+
+
+async def last_message_previews_by_sessions(
+    session: AsyncSession, session_ids: list[str]
+) -> dict[str, str]:
+    """批量取每个会话最后一条未删除消息的内容（截断由调用方处理）。
+
+    用 row_number() 窗口函数取每个 session_id 的最新一条，兼容 SQLite（3.25+）
+    与 PostgreSQL，避免逐会话查询（N+1）。无消息的会话不在结果中。
+    """
+    if not session_ids:
+        return {}
+    latest = (
+        select(
+            ChatMessage.session_id,
+            ChatMessage.content,
+            func.row_number()
+            .over(
+                partition_by=ChatMessage.session_id,
+                order_by=ChatMessage.created_at.desc(),
+            )
+            .label("rn"),
+        ).where(
+            ChatMessage.session_id.in_(session_ids),
+            ChatMessage.deleted_at.is_(None),
+        )
+    ).subquery()
+    result = await session.execute(
+        select(latest.c.session_id, latest.c.content).where(latest.c.rn == 1)
+    )
+    return {str(sid): (content or "") for sid, content in result.all()}
+
+
+async def count_messages_by_role(session: AsyncSession, session_id: str, *, role: str) -> int:
+    """统计会话内指定角色的未删除消息数（用于判断首轮对话）。"""
+    result = await session.execute(
+        select(func.count())
+        .select_from(ChatMessage)
+        .where(
+            ChatMessage.session_id == session_id,
+            ChatMessage.role == role,
+            ChatMessage.deleted_at.is_(None),
+        )
+    )
+    return result.scalar_one()
+
+
+async def update_session_title(session: AsyncSession, session_id: str, title: str) -> None:
+    """更新会话标题；仅修改托管对象，提交时机由调用方控制。"""
+    chat_session = await session.get(ChatSession, session_id)
+    if chat_session is not None:
+        chat_session.title = title
+
+
+async def soft_delete_session_messages(session: AsyncSession, session_id: str) -> None:
+    """软删除会话内全部未删除消息；提交时机由调用方控制。"""
+    from app.core.time import utc_now
+
+    await session.execute(
+        update(ChatMessage)
+        .where(
+            ChatMessage.session_id == session_id,
+            ChatMessage.deleted_at.is_(None),
+        )
+        .values(deleted_at=utc_now())
+    )
+
+
+async def get_message(session: AsyncSession, message_id: str) -> ChatMessage | None:
+    """按 ID 获取单条消息。"""
+    return await session.get(ChatMessage, message_id)
+
+
+async def set_message_active_version(
+    session: AsyncSession,
+    message_id: str,
+    version_idx: int,
+    versions_json: str,
+) -> None:
+    """更新消息的活跃版本索引和 versions_json。"""
+    from sqlalchemy import update
+
+    result = await session.execute(
+        update(ChatMessage)
+        .where(ChatMessage.id == message_id)
+        .values(active_version_idx=version_idx, versions_json=versions_json)
+    )
+    if result.rowcount == 0:
+        raise AppError("not_found", "消息不存在。")