const DEFAULT_POST_SELECTOR = ".post";
const DEFAULT_STYLE = "tldr";

function $(root, selector) {
  const el = root.querySelector(selector);
  if (!el) throw new Error(`Missing element: ${selector}`);
  return el;
}

function compactText(text) {
  return text.replace(/\s+/g, " ").trim();
}

function escapeHtml(s) {
  return s
    .replaceAll("&", "&")
    .replaceAll("<", "&lt;")
    .replaceAll(">", "&gt;");
}

async function fetchJson(url, init) {
  const res = await fetch(url, init);
  const data = await res.json().catch(() => ({}));
  return { res, data };
}

function renderMarkdownish(container, style, summary) {
  if (style === "bullets") {
    const lines = summary
      .split("\n")
      .map((l) => l.trim())
      .filter(Boolean);
    const items = lines
      .map((l) => (l.startsWith("-") ? l.replace(/^-+\s*/, "") : l))
      .filter(Boolean);
    container.innerHTML = `<ul>${items
      .map((i) => `<li>${escapeHtml(i)}</li>`)
      .join("")}</ul>`;
    return;
  }

  if (style === "outline") {
    const blocks = summary.split("\n");
    const html = [];
    for (const line of blocks) {
      const l = line.trimEnd();
      if (!l) continue;
      if (l.startsWith("###")) {
        html.push(`<h4>${escapeHtml(l.replace(/^###\s*/, ""))}</h4>`);
      } else {
        html.push(`<p>${escapeHtml(l)}</p>`);
      }
    }
    container.innerHTML = html.join("");
    return;
  }

  container.textContent = summary;
}

async function ensureSummary(root) {
  const widget = root;
  const title = widget.dataset.title || "摘要";
  const autoload =
    widget.dataset.autoload !== "false" && widget.dataset.autoload !== "0";
  if (widget.dataset.expanded == null) widget.dataset.expanded = "false";
  const needsScaffold =
    !widget.querySelector(".post-summary__status") ||
    !widget.querySelector(".post-summary__content") ||
    !widget.querySelector(".post-summary__styles");
  if (needsScaffold) {
    widget.innerHTML = `
      <div class="post-summary__header">
        <div class="post-summary__title"></div>
        <div class="post-summary__styles" aria-label="Summary styles"></div>
      </div>
      <div class="post-summary__body">
        <div class="post-summary__status post-summary__muted">等待生成…</div>
        <div class="post-summary__content"></div>
      </div>
    `.trim();
    const titleEl = widget.querySelector(".post-summary__title");
    if (titleEl) titleEl.textContent = title;
  } else {
    const titleEl = widget.querySelector(".post-summary__title");
    if (titleEl && !titleEl.textContent) titleEl.textContent = title;
  }

  const postSelector = widget.dataset.postSelector || DEFAULT_POST_SELECTOR;
  const inferredBase = (() => {
    try {
      return new URL(import.meta.url).origin;
    } catch {
      return "";
    }
  })();
  const apiBase = (widget.dataset.apiBase || inferredBase).replace(/\/$/, "");
  const urlKey = widget.dataset.url || location.pathname + location.search;

  const statusEl = $(widget, ".post-summary__status");
  const contentEl = $(widget, ".post-summary__content");
  const stylesEl = $(widget, ".post-summary__styles");

  const updatePressed = (style) => {
    for (const btn of stylesEl.querySelectorAll("button[data-style]")) {
      btn.setAttribute(
        "aria-pressed",
        btn.dataset.style === style ? "true" : "false"
      );
    }
  };

  const setStyle = async (style) => {
    widget.dataset.expanded = "true";
    widget.dataset.style = style;
    updatePressed(style);

    statusEl.textContent = "读取缓存…";
    contentEl.textContent = "";

    const { res, data } = await fetchJson(
      `${apiBase}/api/summary?url=${encodeURIComponent(urlKey)}&style=${encodeURIComponent(
        style
      )}`
    );

    if (res.ok && typeof data?.summary === "string" && data.summary) {
      statusEl.textContent = data.cached ? "来自 KV 缓存" : "已生成";
      renderMarkdownish(contentEl, style, data.summary || "");
      return;
    }

    const isCacheMiss = res.status === 404 || data?.error === "Not found";
    if (!isCacheMiss) {
      statusEl.textContent = `请求失败：${res.status}`;
      contentEl.textContent = data?.error || "Unknown error";
      return;
    }

    const postEl = document.querySelector(postSelector);
    if (!postEl) {
      statusEl.textContent = `未找到文章元素：${postSelector}`;
      return;
    }

    const rawText = compactText(postEl.innerText || postEl.textContent || "");
    if (!rawText) {
      statusEl.textContent = "文章内容为空";
      return;
    }

    const MAX_CHARS = 20000;
    const text = rawText.slice(0, MAX_CHARS);

    statusEl.textContent = "AI 生成中…";
    const created = await fetchJson(`${apiBase}/api/summary`, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ url: urlKey, style, text }),
    });

    if (!created.res.ok) {
      statusEl.textContent = `生成失败：${created.res.status}`;
      contentEl.textContent = created.data?.error || "Unknown error";
      return;
    }

    statusEl.textContent = created.data.cached ? "来自 KV 缓存" : "已生成";
    renderMarkdownish(contentEl, style, created.data.summary || "");
  };

  stylesEl.innerHTML = "";
  const styleList = [
    { key: "tldr", label: "TL;DR" },
    { key: "bullets", label: "要点" },
    { key: "outline", label: "结构化" },
    { key: "keywords", label: "关键词" },
  ];

  for (const { key, label } of styleList) {
    const btn = document.createElement("button");
    btn.type = "button";
    btn.dataset.style = key;
    btn.textContent = label;
    btn.addEventListener("click", () => setStyle(key));
    stylesEl.appendChild(btn);
  }

  const initialStyle = widget.dataset.style || DEFAULT_STYLE;
  widget.dataset.style = initialStyle;
  updatePressed(initialStyle);

  if (autoload) {
    widget.dataset.expanded = "true";
    await setStyle(initialStyle);
  } else {
    widget.dataset.expanded = "false";
    statusEl.textContent = "点击上方风格生成摘要…";
    contentEl.textContent = "";
  }
}

for (const widget of document.querySelectorAll(".post-summary")) {
  ensureSummary(widget).catch((err) => {
    const statusEl = widget.querySelector(".post-summary__status");
    if (statusEl) statusEl.textContent = `初始化失败：${err.message || err}`;
  });
}