"""Embedding provider 工厂:根据配置构造合适后端。

配置优先级: 显式参数 > configs/llm_models.yaml scenes.embedding > .env > 默认。
"""

from __future__ import annotations

from configs.loader import load_scene_config
from configs.runtime_env import env_get

from .base import AsyncEmbeddingProvider, EmbeddingProvider
from .models import EmbeddingError, EmbeddingProviderType
from .remote import (
    DashScopeAsyncEmbeddingProvider,
    DashScopeEmbeddingProvider,
)


def _read_env(key: str, default: str | None = None) -> str | None:
    """读取环境变量（先热加载 .env，改文件后无需重启进程）。"""
    return env_get(key, default)


def resolve_provider_type(provider: str | None = None) -> EmbeddingProviderType:
    """根据 provider 参数 / YAML 场景 / env 解析出 EmbeddingProviderType。

    映射:
        dashscope / qwen / remote     -> DASHSCOPE
        local / local-bge / bge / bge-m3 -> LOCAL_BGE
    默认 dashscope。
    """
    scene_provider = load_scene_config("embedding").get("provider")
    p = (
        provider
        or scene_provider
        or _read_env("EMBEDDING_PROVIDER", "dashscope")
        or "dashscope"
    ).lower()
    if p in ("dashscope", "qwen", "remote"):
        return EmbeddingProviderType.DASHSCOPE
    if p in ("local", "local-bge", "bge", "bge-m3"):
        return EmbeddingProviderType.LOCAL_BGE
    raise EmbeddingError(f"未知 embedding provider: {provider!r}")


def make_sync_provider(
    provider: str | None = None,
    **kwargs: object,
) -> EmbeddingProvider:
    """构造同步 provider。"""
    pt = resolve_provider_type(provider)
    if pt == EmbeddingProviderType.DASHSCOPE:
        return DashScopeEmbeddingProvider(**kwargs)  # type: ignore[arg-type]
    # 本地后端
    from .local import LocalBGEEmbeddingProvider
    return LocalBGEEmbeddingProvider(**kwargs)  # type: ignore[arg-type]


def make_async_provider(
    provider: str | None = None,
    **kwargs: object,
) -> AsyncEmbeddingProvider:
    """构造异步 provider。"""
    pt = resolve_provider_type(provider)
    if pt == EmbeddingProviderType.DASHSCOPE:
        return DashScopeAsyncEmbeddingProvider(**kwargs)  # type: ignore[arg-type]
    from .local import LocalBGEAsyncEmbeddingProvider
    return LocalBGEAsyncEmbeddingProvider(**kwargs)  # type: ignore[arg-type]