"""腾讯 MaaS 翻译(OpenAI 兼容协议)。

- 端点:https://maas-api.hivoice.cn/v1
- 模型:u2(翻译专用)
- 鉴权:Bearer token(api_key 直接当 Bearer)
- 请求:POST /chat/completions,system prompt 告诉模型做翻译

设计上独立于 LlmClient(不走 agnes_* 配置),专门走 tencent_maas_* 配置,
避免和 LLM 智能增强共用 client 的节流。
"""
from __future__ import annotations

import asyncio
import logging
import random

import httpx

from app.config import settings
from app.services.translation.base import BaseTranslator, TranslationResult

logger = logging.getLogger("news.translate.tencent_maas")


# 简单的源/目标语言映射(MaaS 模型期望 ISO 639-1 代码)
_LANG_MAP = {
    "en": "English",
    "zh": "Chinese",
    "ja": "Japanese",
    "ko": "Korean",
    "fr": "French",
    "de": "German",
    "es": "Spanish",
    "ru": "Russian",
    "ar": "Arabic",
}


def _lang_label(code: str) -> str:
    """把 ISO 639-1 转成自然语言名(给模型做 prompt 用)。"""
    if not code or code == "auto":
        return "the source language"
    c = code.split("-")[0].lower()
    return _LANG_MAP.get(c, c)


# 经过反复测试,这个 prompt 是云知声 u2 模型的关键:
# - 明确禁止 reasoning / 分析 / 注释(否则模型会把译文放进 reasoning_content)
# - 限定只接 EN/JA → ZH(对应用户场景)
# - 非英日输入时返回固定拒绝文案(便于上层识别)
_SYSTEM_PROMPT = """你是一个即时翻译助手。对于用户输入的英文或日文文章,请直接输出对应的简体中文译文。严格遵守:

不要进行任何分步思考、不要输出分析、不要添加注释或说明。

只输出中文译文本身,不包含任何额外文字(如"翻译结果:"、"以下是中文:"等)。

如果输入内容既非英文也非日文,仅回复:"仅支持英文或日文翻译为中文。" """


class TencentMaaSTranslator(BaseTranslator):
    """腾讯 MaaS 翻译(OpenAI 兼容协议,模型 u2)。"""

    name = "tencent_maas"

    def __init__(self):
        if not settings.tencent_maas_api_key:
            raise RuntimeError("Tencent MaaS api_key missing")
        self.api_key = settings.tencent_maas_api_key
        self.base_url = settings.tencent_maas_base_url.rstrip("/")
        self.model = settings.tencent_maas_model
        self.interval_sec = settings.tencent_maas_interval_sec

    def is_configured(self) -> bool:
        return bool(self.api_key)

    async def translate(
        self, text: str, source: str = "auto", target: str = "zh"
    ) -> TranslationResult:
        """翻译接口。

        注意:source/target 参数当前被忽略,因为 u2 模型在固定 system prompt 下
        会自行判断 EN/JA → ZH;保留参数是为了兼容 BaseTranslator 接口。
        """
        if not text.strip():
            return TranslationResult(text=text, engine=self.name, chars=0)

        if not self.is_configured():
            raise RuntimeError("Tencent MaaS api_key missing")

        # 固定 system prompt(经过反复测试,这套 prompt 是云知声 u2 模型唯一能稳定输出
        # 译文到 content 字段的写法;改 prompt 格式会导致模型把译文放进 reasoning_content)
        system = _SYSTEM_PROMPT
        user = text

        url = f"{self.base_url}/chat/completions"
        payload = {
            "model": self.model,
            "messages": [
                {"role": "system", "content": system},
                {"role": "user", "content": user},
            ],
            "temperature": 0.0,
            "max_tokens": max(256, len(text) * 3),
        }
        headers = {
            "Authorization": f"Bearer {self.api_key}",
            "Content-Type": "application/json",
        }

        # 简单串行 + 重试 1 次
        last_exc: Exception | None = None
        for attempt in range(2):
            try:
                async with httpx.AsyncClient(timeout=60.0) as client:
                    r = await client.post(url, json=payload, headers=headers)
                if r.status_code >= 500:
                    raise RuntimeError(f"TencentMaas 5xx: {r.status_code} {r.text[:200]}")
                if r.status_code != 200:
                    raise RuntimeError(f"TencentMaas {r.status_code}: {r.text[:300]}")
                data = r.json()
                content = (
                    data.get("choices", [{}])[0]
                    .get("message", {})
                    .get("content", "")
                    .strip()
                )
                if not content:
                    raise RuntimeError(f"TencentMaas empty content: {r.text[:300]}")
                # 节流(避免被 MaaS 限流)
                await asyncio.sleep(self.interval_sec)
                return TranslationResult(
                    text=content, engine=self.name, chars=len(text), cached=False
                )
            except Exception as e:
                last_exc = e
                logger.warning("tencent_maas attempt %s failed: %s", attempt, e)
                if attempt == 0:
                    await asyncio.sleep(0.5 + random.random())
                else:
                    raise
        # 不可达
        assert last_exc is not None
        raise last_exc