"""Embedding provider 工厂:根据环境变量构造合适后端。"""

from __future__ import annotations

import os

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:
    val = os.environ.get(key)
    if val is None or val.strip() == "":
        return default
    return val.strip()


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

    映射:
        dashscope / qwen / remote     -> DASHSCOPE
        local / local-bge / bge / bge-m3 -> LOCAL_BGE
    默认 dashscope。
    """
    p = (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]