Letters/js/notice-banner.js

(function () {
    var currentScript = document.currentScript;
    var source = currentScript && currentScript.getAttribute("data-notice-src");

    if (!source && currentScript && currentScript.src) {
        source = currentScript.src.replace(/js\/notice-banner\.js(?:\?.*)?$/, "notices.json");
    }

    if (!source) {
        source = "notices.json";
    }

    var cacheKey = Math.floor(Date.now() / (5 * 60 * 1000));
    var joiner = source.indexOf("?") === -1 ? "?" : "&";

    fetch(source + joiner + "v=" + cacheKey, { cache: "no-store" })
        .then(function (response) {
            if (!response.ok) {
                throw new Error("Notice source unavailable");
            }
            return response.json();
        })
        .then(function (payload) {
            var notice = selectNotice(payload);
            if (notice) {
                renderNotice(notice);
            }
        })
        .catch(function () {
            // The page should stay quiet when the optional notice source is missing.
        });

    function selectNotice(payload) {
        var notices = Array.isArray(payload) ? payload : payload && payload.notices;

        if (!Array.isArray(notices)) {
            return null;
        }

        var now = Date.now();
        var path = normalizePath(window.location.pathname);

        return notices.find(function (notice) {
            if (!notice || notice.enabled === false) {
                return false;
            }

            if (notice.startsAt && Date.parse(notice.startsAt) > now) {
                return false;
            }

            if (notice.endsAt && Date.parse(notice.endsAt) < now) {
                return false;
            }

            if (notice.pages && notice.pages.length) {
                return notice.pages.some(function (page) {
                    return pathMatches(path, normalizePath(page));
                });
            }

            return true;
        });
    }

    function renderNotice(notice) {
        var dismissedId = window.localStorage.getItem("dismissedNoticeId");
        var noticeId = String(notice.id || "");

        if (notice.dismissible !== false && noticeId && dismissedId === noticeId) {
            return;
        }

        var body = document.body;
        var originalPadding = window.getComputedStyle(body).paddingTop || "0px";
        body.style.setProperty("--notice-body-pad-top", originalPadding);

        var banner = document.createElement("div");
        banner.className = "notice-banner";
        banner.setAttribute("role", "status");
        banner.setAttribute("aria-live", "polite");
        banner.dataset.level = notice.level || "info";

        var inner = document.createElement("div");
        inner.className = "notice-banner__inner";

        var badge = document.createElement("span");
        badge.className = "notice-banner__badge";
        badge.textContent = notice.badge || levelLabel(notice.level);

        var content = document.createElement("div");
        content.className = "notice-banner__content";

        if (notice.title) {
            var title = document.createElement("span");
            title.className = "notice-banner__title";
            title.textContent = notice.title;
            content.appendChild(title);
        }

        var message = document.createElement("span");
        message.className = "notice-banner__message";
        message.textContent = notice.message || "";
        content.appendChild(message);

        inner.appendChild(badge);
        inner.appendChild(content);

        if (notice.url) {
            var link = document.createElement("a");
            link.className = "notice-banner__link";
            link.href = resolveUrl(notice.url, source);
            link.textContent = notice.linkText || "查看详情";
            inner.appendChild(link);
        }

        var close = document.createElement("button");
        close.className = "notice-banner__close";
        close.type = "button";
        close.setAttribute("aria-label", "关闭通知");
        close.textContent = "×";
        close.addEventListener("click", function () {
            if (notice.dismissible !== false && noticeId) {
                window.localStorage.setItem("dismissedNoticeId", noticeId);
            }
            banner.remove();
            body.classList.remove("has-notice-banner");
            body.style.removeProperty("--notice-banner-height");
        });

        inner.appendChild(close);
        banner.appendChild(inner);
        body.insertBefore(banner, body.firstChild);

        requestAnimationFrame(function () {
            banner.classList.add("is-visible");
            body.style.setProperty("--notice-banner-height", banner.offsetHeight + "px");
            body.classList.add("has-notice-banner");
        });
    }

    function levelLabel(level) {
        var labels = {
            warning: "提醒",
            error: "紧急",
            success: "完成"
        };

        return labels[level] || "通知";
    }

    function normalizePath(path) {
        return String(path || "").replace(/\\/g, "/").replace(/^.*?:\/\/[^/]+/, "");
    }

    function resolveUrl(url, base) {
        try {
            return new URL(url, new URL(base, window.location.href)).href;
        } catch (error) {
            return url;
        }
    }

    function pathMatches(path, pattern) {
        if (!pattern || pattern === "*") {
            return true;
        }

        if (pattern.charAt(pattern.length - 1) === "*") {
            return path.indexOf(pattern.slice(0, -1)) === 0;
        }

        return path === pattern || path.endsWith(pattern);
    }
})();