/* Common helpers shared across pages (ES module). */

/**
 * Debounce a function call.
 * @param {Function} fn - function to debounce
 * @param {number} delay - delay in ms
 */
export function debounce(fn, delay) {
    let timer = null;
    return function (...args) {
        clearTimeout(timer);
        timer = setTimeout(() => fn.apply(this, args), delay);
    };
}

/**
 * Format an ISO date string to YYYY-MM-DD.
 * Returns empty string for falsy input.
 */
export function formatDate(isoString) {
    if (!isoString) return "";
    const d = new Date(isoString);
    if (isNaN(d.getTime())) return String(isoString).slice(0, 10);
    const y = d.getFullYear();
    const m = String(d.getMonth() + 1).padStart(2, "0");
    const day = String(d.getDate()).padStart(2, "0");
    return `${y}-${m}-${day}`;
}

/** Truncate text to maxLen chars, appending ellipsis. */
export function truncate(text, maxLen) {
    if (!text) return "";
    const s = String(text);
    return s.length > maxLen ? s.slice(0, maxLen) + "…" : s;
}

/** Escape HTML special chars to prevent XSS when injecting via innerHTML. */
export function escapeHtml(text) {
    if (text === null || text === undefined) return "";
    return String(text)
        .replace(/&/g, "&")
        .replace(/</g, "&lt;")
        .replace(/>/g, "&gt;")
        .replace(/"/g, "&quot;")
        .replace(/'/g, "&#39;");
}

/** Fetch JSON with basic error handling. */
export async function fetchJson(url) {
    const resp = await fetch(url);
    if (!resp.ok) {
        throw new Error(`请求失败: ${resp.status} ${resp.statusText}`);
    }
    return resp.json();
}

/* Delegated retry: covers .js-retry-btn injected into error hints after load. */
document.addEventListener("click", (e) => {
    if (e.target.closest(".js-retry-btn")) location.reload();
});