chrome_plus_Transly/background.js

const SYSTEM_PROMPT = "你是翻译引擎，只输出译文，不解释不分析不扩展";

function setupContextMenu() {
  chrome.contextMenus.removeAll(() => {
    chrome.contextMenus.create({
      id: "transly-translate-selection",
      title: "Transly: 翻译选中文本",
      contexts: ["selection"]
    });
  });
}

chrome.runtime.onInstalled.addListener((details) => {
  setupContextMenu();
  if (details.reason === "install") {
    chrome.runtime.openOptionsPage();
  }
});
chrome.runtime.onStartup.addListener(setupContextMenu);

async function getConfig() {
  const syncData = await chrome.storage.sync.get({
    baseUrl: "https://api.openai.com",
    model: "gpt-4o-mini",
    targetLang: "zh-CN"
  });
  const localData = await chrome.storage.local.get({ apiKey: "" });

  return normalizeConfig({
    ...syncData,
    ...localData
  });
}

function normalizeConfig(config) {
  return {
    baseUrl: String(config?.baseUrl || "").trim().replace(/\/+$/, ""),
    apiKey: String(config?.apiKey || "").trim(),
    model: String(config?.model || "").trim(),
    targetLang: String(config?.targetLang || "zh-CN").trim() || "zh-CN"
  };
}

function parseContent(content) {
  if (Array.isArray(content)) {
    return content.map((item) => item?.text || "").join("").trim();
  }
  return String(content || "").trim();
}

async function requestTranslate(text, useReasoningEffort, configOverride) {
  const cfg = configOverride ? normalizeConfig(configOverride) : await getConfig();
  const { baseUrl, apiKey, model, targetLang } = cfg;
  if (!baseUrl || !apiKey || !model) {
    throw new Error("请先在 options 填写 Base URL / API Key / Model");
  }

  const body = {
    model,
    temperature: 0,
    messages: [
      { role: "system", content: SYSTEM_PROMPT },
      { role: "user", content: `请翻译为 ${targetLang}，只输出译文：\n${text}` }
    ]
  };

  if (useReasoningEffort) {
    body.reasoning_effort = "low";
  }

  const res = await fetch(`${baseUrl}/v1/chat/completions`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
      Authorization: `Bearer ${apiKey}`
    },
    body: JSON.stringify(body)
  });

  if (!res.ok) {
    const errText = (await res.text()).slice(0, 200);
    throw new Error(`请求失败(${res.status}) ${errText}`);
  }

  const data = await res.json();
  const translated = parseContent(data?.choices?.[0]?.message?.content);
  if (!translated) {
    throw new Error("未收到有效译文");
  }

  return translated;
}

async function translate(text, configOverride) {
  if (!text || !text.trim()) {
    throw new Error("没有可翻译文本");
  }

  try {
    return await requestTranslate(text.trim(), true, configOverride);
  } catch (err) {
    const message = String(err?.message || "");
    if (message.includes("400") || message.includes("reasoning")) {
      return requestTranslate(text.trim(), false, configOverride);
    }
    throw err;
  }
}

async function testConfig(configInput) {
  const cfg = normalizeConfig(configInput);
  if (!cfg.baseUrl || !cfg.apiKey || !cfg.model) {
    throw new Error("请先填写 Base URL / API Key / Model");
  }

  await translate("hello world", cfg);
  return "连接成功，API Key 与模型可用";
}

async function getSelectedTextFromTab(tabId) {
  const results = await chrome.scripting.executeScript({
    target: { tabId },
    func: () => {
      const selected = String(window.getSelection() || "").trim();
      if (selected) {
        return selected;
      }

      const el = document.activeElement;
      if (!el) {
        return "";
      }

      const isInput = el.tagName === "INPUT" || el.tagName === "TEXTAREA";
      if (!isInput || typeof el.value !== "string") {
        return "";
      }

      const start = el.selectionStart ?? 0;
      const end = el.selectionEnd ?? 0;
      return el.value.slice(Math.min(start, end), Math.max(start, end)).trim();
    }
  });

  return String(results?.[0]?.result || "").trim();
}

async function showTextInTab(tabId, text, isError) {
  const message = String(text || "").trim();
  if (!message) {
    return false;
  }

  try {
    await chrome.scripting.executeScript({
      target: { tabId },
      func: (msg, error) => {
        alert(error ? `Transly: ${msg}` : msg);
      },
      args: [message, !!isError]
    });
    return true;
  } catch (_err) {
    // 某些页面禁止注入，降级尝试 content script 消息。
  }

  return new Promise((resolve) => {
    chrome.tabs.sendMessage(
      tabId,
      isError ? { action: "showError", error: message } : { action: "showTranslation", text: message },
      (response) => {
        if (chrome.runtime.lastError || !response?.ok) {
          resolve(false);
          return;
        }
        resolve(true);
      }
    );
  });
}

async function translateSelectionInTab(tabId) {
  const selectedText = await getSelectedTextFromTab(tabId);
  if (!selectedText) {
    throw new Error("请先选中文本");
  }

  const text = await translate(selectedText);
  const shown = await showTextInTab(tabId, text, false);
  return { text, shown };
}

chrome.runtime.onMessage.addListener((message, _sender, sendResponse) => {
  if (message?.action === "translate") {
    translate(message.text)
      .then((text) => sendResponse({ ok: true, text }))
      .catch((err) => sendResponse({ ok: false, error: err.message || "翻译失败" }));

    return true;
  }

  if (message?.action === "translateSelectionInTab") {
    translateSelectionInTab(message.tabId)
      .then((result) => sendResponse({ ok: true, text: result.text, shown: result.shown }))
      .catch((err) => sendResponse({ ok: false, error: err.message || "翻译失败" }));

    return true;
  }

  if (message?.action === "testConfig") {
    testConfig(message.config)
      .then((text) => sendResponse({ ok: true, text }))
      .catch((err) => sendResponse({ ok: false, error: err.message || "测试失败" }));

    return true;
  }
});

chrome.contextMenus.onClicked.addListener(async (info, tab) => {
  if (info.menuItemId !== "transly-translate-selection" || !info.selectionText || !tab?.id) {
    return;
  }

  try {
    const text = await translate(info.selectionText);
    await showTextInTab(tab.id, text, false);
  } catch (err) {
    await showTextInTab(tab.id, err.message || "翻译失败", true);
  }
});