import base64
from collections.abc import Mapping
from typing import Any

import httpx

from app.config import Settings


class BaiduOcrAdapter:
    OCR_URL = "https://aip.baidubce.com/rest/2.0/ocr/v1/accurate_basic"

    def __init__(self, settings: Settings | Mapping[str, Any]) -> None:
        self.settings = settings

    def _value(self, key: str, default: str | bool = "") -> str | bool:
        if isinstance(self.settings, Mapping):
            return self.settings.get(key, default)
        return getattr(self.settings, key, default)

    @property
    def configured(self) -> bool:
        return bool(
            self._value("baidu_ocr_enabled")
            and self._value("baidu_ocr_api_key")
            and self._value("baidu_ocr_secret_key")
        )

    async def _access_token(self) -> str:
        async with httpx.AsyncClient(timeout=20) as client:
            response = await client.post(
                str(self._value("baidu_ocr_token_url", "https://aip.baidubce.com/oauth/2.0/token")),
                params={
                    "grant_type": "client_credentials",
                    "client_id": self._value("baidu_ocr_api_key"),
                    "client_secret": self._value("baidu_ocr_secret_key"),
                },
            )
            response.raise_for_status()
            return response.json()["access_token"]

    async def recognize(self, image_bytes: bytes) -> list[dict]:
        if not self.configured:
            raise RuntimeError("Baidu OCR is not configured or enabled.")
        token = await self._access_token()
        async with httpx.AsyncClient(timeout=60) as client:
            response = await client.post(
                self.OCR_URL,
                params={"access_token": token},
                data={
                    "image": base64.b64encode(image_bytes).decode("ascii"),
                    "detect_direction": "true",
                    "paragraph": "false",
                },
                headers={"Content-Type": "application/x-www-form-urlencoded"},
            )
            response.raise_for_status()
            return response.json().get("words_result", [])