"""向量存储接口与工厂。

通过 ``get_vector_store()`` 获取当前配置的后端实现：
- ``chromadb``（默认）：ChromaDB，内存/HTTP 双模式
- ``memory``：纯内存实现（测试用）

通过环境变量 ``CHROMADB_HOST`` / ``CHROMADB_PORT`` 控制 ChromaDB 连接模式。
通过 ``ENABLE_EMBEDDING=false`` 关闭 embedding（纯 SQL 检索）。
通过 ``VECTOR_DB_TYPE=chroma`` 选择向量库后端。
"""

from __future__ import annotations

from typing import Any, Protocol, runtime_checkable


@runtime_checkable
class VectorStoreProtocol(Protocol):
    """向量存储接口。所有后端实现必须遵循此协议。"""

    def add_memory(
        self,
        character_id: str,
        memory_id: str,
        text: str,
        embedding: list[float],
        *,
        metadata: dict[str, Any] | None = None,
    ) -> None: ...

    def update_memory(
        self,
        character_id: str,
        memory_id: str,
        text: str,
        embedding: list[float],
        *,
        metadata: dict[str, Any] | None = None,
    ) -> None: ...

    def delete_memory(self, character_id: str, memory_id: str) -> None: ...

    def search(
        self,
        character_id: str,
        query: list[float],
        *,
        limit: int = 5,
    ) -> list[dict[str, Any]]: ...

    def count(self, character_id: str) -> int: ...


_vector_store: VectorStoreProtocol | None = None


def get_vector_store() -> VectorStoreProtocol | None:
    """根据配置返回向量存储后端；embedding 关闭时返回 None。"""
    from app.core.config import settings

    if not settings.vector_db_enabled:
        return None

    global _vector_store  # noqa: PLW0603
    if _vector_store is not None:
        return _vector_store

    backend = settings.vector_db_type
    if backend == "memory":
        from app.integrations.chromadb.memory_store import MemoryVectorStore

        _vector_store = MemoryVectorStore()
    else:
        # 默认 chromadb
        from app.integrations.chromadb.client import ChromaDBVectorStore

        _vector_store = ChromaDBVectorStore()
    return _vector_store


def reset_vector_store() -> None:
    """重置单例（测试用）。"""
    global _vector_store  # noqa: PLW0603
    _vector_store = None