document.addEventListener("DOMContentLoaded", async function () {
    try {
        // 尝试请求 secret.key 以验证关键安全文件是否存在
        let response = await fetch('secret.key', {
            method: 'HEAD',
            headers: {
                'Cache-Control': 'no-store, no-cache, must-revalidate, proxy-revalidate',
                'Pragma': 'no-cache',
                'Expires': '0'
            }
        });
        if (!response.ok) {
            throw new Error("secret.key 不存在或无法访问");
        }
    } catch (error) {
        // 处理错误，显示安全警告
        console.error("安全检查失败：", error);
        document.body.innerHTML = `<div style="text-align: center; padding: 50px; font-size: 24px; color: green;">
            <div style="display: flex; justify-content: center; align-items: center; flex-direction: column; border: 2px solid green; padding: 20px; border-radius: 10px; background: #e6ffe6; width: 60%; margin: 50px auto;">
                <p style="font-size: 28px; font-weight: bold; color: green;">⚠ 错误提示</p>
                <p style="font-size: 20px;">无法加载关键安全文件。</p>
            </div>
        </div>`;
        return;
    }

    const progressBar = document.querySelector(".progress");
    let progress = 0;
    let fastestUrl = "";
    let timeout;

    // 如果主线路全部检测失败（超时），才会随机打开备用线路。
    const fallbackUrls = [
        atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzcxLw=="),
        atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzcyLw=="),
        atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzczLw=="),
        atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3Nzc0Lw==")
    ];

    // 首先检测主线路（进行测速）自动打开最快线路。
    const routes = [
        { url: atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzcxLw=="), text: "①线路" },
        { url: atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzcyLw=="), text: "②线路" },
        { url: atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3NzczLw=="), text: "③线路" },
        { url: atob("aHR0cHM6Ly8xMDMuODIuMjE1LjEyNDo3Nzc0Lw=="), text: "④线路" }
    ];

    // 开始倒计时，5 秒后跳转到最快的线路
    function startTimeout() {
        timeout = setTimeout(function () {
            window.location.href = fastestUrl;
        }, 5000);
    }

    // 进度条模拟加载进度
    function updateProgress() {
        if (progress < 100) {
            progress += Math.random() * 20; // 随机增加进度
            if (progress > 100) progress = 100;
            progressBar.style.width = progress + "%";
            setTimeout(updateProgress, 500);    
        }
    }
    updateProgress();

    const routeButtons = document.getElementById("route-buttons");

    // 创建线路按钮
    routes.forEach(route => {
        let a = document.createElement("a");
        a.href = route.url;
        a.className = "route-btn";
        a.innerText = `${route.text} → 检测中...`;
        routeButtons.appendChild(a);
        route.element = a;
    });

    // 测试线路速度
    async function measureSpeed(url, retries = 2) {
        const controller = new AbortController();
        const timeoutId = setTimeout(() => controller.abort(), 5000);
        const start = performance.now();
        let success = false;
        try {
            await fetch(`${url}/favicon.ico`, { method: 'HEAD', mode: 'no-cors', signal: controller.signal });
            success = true;
        } catch (e) {
            if (retries > 1) {
                return measureSpeed(url, retries - 1);
            }
        }
        clearTimeout(timeoutId);
        const elapsed = (performance.now() - start) / 1000;
        return success ? parseFloat(elapsed.toFixed(2)) : Infinity;
    }

    // 更新线路状态并选择最快线路
    async function updateRoutes() {
        let mainSpeeds = await Promise.all(routes.map(route => measureSpeed(route.url)));
        let allMainFailed = mainSpeeds.every(speed => speed === Infinity);
        let bestIndexes = [];

        if (allMainFailed) {
            // 如果所有主线路失败，则测试备用线路
            let fallbackSpeeds = await Promise.all(fallbackUrls.map(url => measureSpeed(url)));
            let minFallbackSpeed = Math.min(...fallbackSpeeds);

            bestIndexes = fallbackSpeeds
                .map((speed, index) => (speed === minFallbackSpeed ? index : -1))
                .filter(index => index !== -1);

            fastestUrl = fallbackUrls[bestIndexes[Math.floor(Math.random() * bestIndexes.length)]];
        } else {
            let minMainSpeed = Math.min(...mainSpeeds);

            bestIndexes = mainSpeeds
                .map((speed, index) => (speed === minMainSpeed ? index : -1))
                .filter(index => index !== -1);

            fastestUrl = routes[bestIndexes[Math.floor(Math.random() * bestIndexes.length)]].url;
        }

        // 更新按钮显示速度信息
        routes.forEach((route, index) => {
            let speed = mainSpeeds[index];
            let speedText = speed === Infinity ? '超时' : `${speed}秒`;
            let category = speed === Infinity ? '超时' : speed === Math.min(...mainSpeeds) ? '最快' : speed <= Math.min(...mainSpeeds) + 0.5 ? '较快' : '一般';
            let color = category === '最快' ? '#008000' : category === '较快' ? '#4A7AC9' : category === '一般' ? '#808080' : '#FF0000';

            route.element.style.backgroundColor = color;
            route.element.style.color = "white";
            route.element.innerText = `${route.text} → 点击前往 ${speedText} (${category})`;
        });

        clearTimeout(timeout);
        startTimeout();
    }

    updateRoutes();
});