import {
  coverUrl, escapeAttr, escapeHtml, formatCount, formatDate,
  formatDelta, formatDuration, formatPercent, metricLabel, statusLabel,
} from "./format.js";

export function cover(item, className = "thumb") {
  const url = coverUrl(item.cover);
  const title = escapeAttr(item.title || "视频封面");
  if (!url) {
    return `<div class="${className} cover-placeholder" aria-hidden="true">无封面</div>`;
  }
  return `<div class="${className}"><img src="${escapeAttr(url)}" alt="${title}"
    loading="lazy" referrerpolicy="no-referrer"></div>`;
}

export function rankBadge(rank) {
  if (!rank) return "";
  const top = rank <= 3 ? ` rank-${rank}` : "";
  return `<span class="rank-badge${top}">${rank}</span>`;
}

export function videoCard(item, { rank = null, primary = "view", showStatus = false } = {}) {
  const metrics = item.metrics || {};
  const primaryValue = metrics[primary];
  const growth = item.growth;
  const delta = growth?.available ? growth.delta : null;
  const title = escapeHtml(item.title || "(无标题)");
  const up = escapeHtml(item.up_name || "未知 UP");
  const upMid = item.up_mid;
  // 卡片本身已经是 <a>，这里不能再嵌套链接，否则 HTML 解析会截断卡片。
  const upLink = upMid ? `<span class="up-name" data-up-mid="${upMid}">${up}</span>` : up;
  const status = showStatus && item.status
    ? `<span class="badge status-${escapeAttr(item.status)}">${escapeHtml(statusLabel(item.status))}</span>` : "";
  return `
    <a class="video-card${rank ? "" : " no-rank"}" href="#/video/${item.aid}" data-aid="${item.aid}">
      ${rankBadge(rank)}
      ${cover(item, "video-thumb")}
      <div class="video-card-body">
        <h3 class="video-title">${title}</h3>
        <div class="video-meta">
          <span>${upLink}</span>
          <span>${escapeHtml(formatDate(item.pubdate))}</span>
          <span>${escapeHtml(formatDuration(item.duration))}</span>
          ${status}
        </div>
        <div class="video-stats">
          <span class="primary-stat">
            <b>${formatCount(primaryValue)}</b><small>${escapeHtml(metricLabel(primary))}</small>
          </span>
          ${delta !== null ? `<span class="delta ${delta >= 0 ? "up" : "down"}">${formatDelta(delta)}</span>` : ""}
          <span class="secondary-stat">赞 ${formatCount(metrics.like)}</span>
          <span class="secondary-stat optional">币 ${formatCount(metrics.coin)}</span>
          <span class="secondary-stat optional">藏 ${formatCount(metrics.favorite)}</span>
          <span class="secondary-stat">互动 ${formatPercent(item.interaction_rate)}</span>
        </div>
      </div>
      <span class="card-arrow" aria-hidden="true">›</span>
    </a>`;
}

export function upCard(item, { rank = null } = {}) {
  const best = item.best_video || {};
  const displayCover = cover(
    { title: best.title || item.up_name, cover: best.cover },
    "video-thumb up-thumb",
  );
  return `
    <a class="up-card" href="#/up/${item.up_mid}">
      ${rankBadge(rank)}
      ${displayCover}
      <div class="up-card-body">
        <h3 class="video-title">${escapeHtml(item.up_name || `UP ${item.up_mid}`)}</h3>
        <div class="video-meta">
          <span>${formatNumber(item.video_count)} 条视频</span>
          <span>均播 ${formatCount(item.avg_views)}</span>
        </div>
        <div class="video-stats">
          <span class="primary-stat"><b>${formatCount(item.total_views)}</b><small>总播放</small></span>
          <span class="secondary-stat">总互动 ${formatCount(item.total_interactions)}</span>
          <span class="secondary-stat">均互动 ${formatPercent(item.avg_interaction)}</span>
        </div>
      </div>
      <span class="card-arrow" aria-hidden="true">›</span>
    </a>`;
}

export function metricGrid(item) {
  const metrics = item.metrics || {};
  const growth = item.growth;
  return `<div class="metric-grid">
    ${["view", "like", "coin", "favorite", "share", "reply", "danmaku"].map((metric) => {
      const extra = metric === "view" && growth?.available
        ? `<span class="metric-delta ${growth.delta >= 0 ? "up" : "down"}">${formatDelta(growth.delta)}</span>`
        : "";
      return `<div class="metric-cell">
        <span class="metric-label">${escapeHtml(metricLabel(metric))}</span>
        <strong>${formatCount(metrics[metric])}</strong>${extra}
      </div>`;
    }).join("")}
  </div>`;
}

export function sectionHeader(title, extra = "") {
  return `<div class="section-head"><h2>${escapeHtml(title)}</h2>${extra}</div>`;
}

export function emptyState(title, message = "", action = "") {
  return `<div class="empty-state"><strong>${escapeHtml(title)}</strong>
    ${message ? `<p>${escapeHtml(message)}</p>` : ""}${action}</div>`;
}

export function badge(text, kind = "subtle") {
  return `<span class="badge ${kind}">${escapeHtml(text)}</span>`;
}

export function chip(label, active, data, value = "") {
  return `<button type="button" class="chip${active ? " active" : ""}" data-${data}="${escapeAttr(value)}">${escapeHtml(label)}</button>`;
}

export function formatNumber(value) {
  return value === null || value === undefined ? "—" : Number(value).toLocaleString("zh-CN");
}

export function metricChips(metrics, active, dataName = "metric") {
  return metrics.map((metric) => chip(
    metricLabel(metric), metric === active, dataName, metric,
  )).join("");
}

export function centerActiveChips(root) {
  root.querySelectorAll(".chip-row.scroll-x").forEach((row) => {
    const active = row.querySelector(".chip.active");
    if (!active) return;
    const target = active.offsetLeft - row.clientWidth / 2 + active.clientWidth / 2;
    row.scrollLeft = Math.max(0, target);
  });
}

export function pager(page, pages) {
  if (!pages || pages <= 1) return "";
  return `<div class="pager">
    <button type="button" class="button ghost" data-page="${page - 1}" ${page <= 1 ? "disabled" : ""}>上一页</button>
    <span>第 ${page} / ${pages} 页</span>
    <button type="button" class="button ghost" data-page="${page + 1}" ${page >= pages ? "disabled" : ""}>下一页</button>
  </div>`;
}