background.js

// background.js

chrome.action.onClicked.addListener(async (tab) => {
    // 检查是否在受限页面
    if (!tab.url || tab.url.startsWith("chrome://") || tab.url.startsWith("edge://") || tab.url.startsWith("about:")) {
        console.warn("Cannot run extension on this page.");
        return;
    }

    try {
        // 尝试发送一个 ping 消息来检测 content script 是否存在
        const response = await chrome.tabs.sendMessage(tab.id, { action: "ping" }).catch(() => null);

        if (!response) {
            console.log("Content script not detected (likely opened before extension install). Injecting scripts...");
            
            // 主动注入脚本
            // 注意：我们不需要注入 CSS 到主文档，因为 content.js 会在 Shadow DOM 中加载 CSS
            await chrome.scripting.executeScript({
                target: { tabId: tab.id },
                files: ["readability.js", "content.js"]
            });
            
            console.log("Scripts injected successfully.");
            
            // 给一点时间让脚本初始化
            await new Promise(resolve => setTimeout(resolve, 100));
        }

        // 发送切换命令
        chrome.tabs.sendMessage(tab.id, { action: "toggleReadingMode" });

    } catch (err) {
        console.error("Failed to execute content script:", err);
    }
});