translator.py

import logging
import time

import httpx
from openai import OpenAI

log = logging.getLogger("LiveTrans.TL")

LANGUAGE_DISPLAY = {
    "en": "English",
    "ja": "Japanese",
    "zh": "Chinese",
    "ko": "Korean",
    "fr": "French",
    "de": "German",
    "es": "Spanish",
    "ru": "Russian",
}

DEFAULT_PROMPT = (
    "You are a subtitle translator. Translate {source_lang} into {target_lang}.\n"
    "Output ONLY the translated text, nothing else.\n"
    "Keep the translation natural, colloquial, and concise."
)


def make_openai_client(
    api_base: str, api_key: str, proxy: str = "none", timeout=None
) -> OpenAI:
    kwargs = {"base_url": api_base, "api_key": api_key}
    if timeout is not None:
        kwargs["timeout"] = httpx.Timeout(timeout, connect=5.0)
    if proxy == "system":
        pass
    elif proxy in ("none", "", None):
        kwargs["http_client"] = httpx.Client(trust_env=False)
    else:
        kwargs["http_client"] = httpx.Client(proxy=proxy)
    return OpenAI(**kwargs)


class Translator:
    """LLM-based translation using OpenAI-compatible API."""

    def __init__(
        self,
        api_base,
        api_key,
        model,
        target_language="zh",
        max_tokens=256,
        temperature=0.3,
        streaming=True,
        system_prompt=None,
        proxy="none",
        no_system_role=False,
        timeout=10,
    ):
        self._client = make_openai_client(api_base, api_key, proxy, timeout=timeout)
        self._no_system_role = no_system_role
        self._model = model
        self._target_language = target_language
        self._max_tokens = max_tokens
        self._temperature = temperature
        self._streaming = streaming
        self._timeout = timeout
        self._system_prompt_template = system_prompt or DEFAULT_PROMPT
        self._last_prompt_tokens = 0
        self._last_completion_tokens = 0

    @property
    def last_usage(self):
        """(prompt_tokens, completion_tokens) from last translate call."""
        return self._last_prompt_tokens, self._last_completion_tokens

    def _build_system_prompt(self, source_lang):
        src = LANGUAGE_DISPLAY.get(source_lang, source_lang)
        tgt = LANGUAGE_DISPLAY.get(self._target_language, self._target_language)
        try:
            return self._system_prompt_template.format(
                source_lang=src,
                target_lang=tgt,
            )
        except (KeyError, IndexError, ValueError) as e:
            log.warning(f"Bad prompt template, falling back to default: {e}")
            return DEFAULT_PROMPT.format(source_lang=src, target_lang=tgt)

    def _build_messages(self, system_prompt, text):
        if self._no_system_role:
            return [{"role": "user", "content": f"{system_prompt}\n{text}"}]
        return [
            {"role": "system", "content": system_prompt},
            {"role": "user", "content": text},
        ]

    def translate(self, text: str, source_language: str = "en"):
        system_prompt = self._build_system_prompt(source_language)
        if self._streaming:
            return self._translate_streaming(system_prompt, text)
        else:
            return self._translate_sync(system_prompt, text)

    def _translate_sync(self, system_prompt, text):
        resp = self._client.chat.completions.create(
            model=self._model,
            messages=self._build_messages(system_prompt, text),
            max_tokens=self._max_tokens,
            temperature=self._temperature,
        )
        self._last_prompt_tokens = 0
        self._last_completion_tokens = 0
        if resp.usage:
            self._last_prompt_tokens = resp.usage.prompt_tokens or 0
            self._last_completion_tokens = resp.usage.completion_tokens or 0
        return resp.choices[0].message.content.strip()

    def _translate_streaming(self, system_prompt, text):
        self._last_prompt_tokens = 0
        self._last_completion_tokens = 0
        base_kwargs = dict(
            model=self._model,
            messages=self._build_messages(system_prompt, text),
            max_tokens=self._max_tokens,
            temperature=self._temperature,
            stream=True,
        )
        try:
            stream = self._client.chat.completions.create(
                **base_kwargs,
                stream_options={"include_usage": True},
            )
        except Exception:
            stream = self._client.chat.completions.create(**base_kwargs)

        deadline = time.monotonic() + self._timeout
        chunks = []
        for chunk in stream:
            if time.monotonic() > deadline:
                stream.close()
                raise TimeoutError(f"Translation exceeded {self._timeout}s total timeout")
            if hasattr(chunk, "usage") and chunk.usage:
                self._last_prompt_tokens = chunk.usage.prompt_tokens or 0
                self._last_completion_tokens = chunk.usage.completion_tokens or 0
            if chunk.choices:
                delta = chunk.choices[0].delta
                if delta.content:
                    chunks.append(delta.content)
        return "".join(chunks).strip()