// ==UserScript==
// @name         学习通课件解析助手
// @namespace    https://github.com/local/chaoxing-courseware-helper
// @version      0.2.0
// @description  在已登录的学习通章节页解析课件，并下载自己有权访问的资源。
// @license      MIT
// @match        *://*.chaoxing.com/*
// @match        *://*.fanya.chaoxing.com/*
// @noframes
// @run-at       document-idle
// @grant        GM_xmlhttpRequest
// @grant        GM_download
// @grant        GM_openInTab
// @grant        GM_setClipboard
// @grant        unsafeWindow
// @connect      *
// ==/UserScript==

/*
 * 仅使用浏览器当前已登录帐号可访问的接口；不保存帐号、密码或 Cookie。
 * 学习通页面与接口可能调整，主要维护点是 getAttachments() 与 resourceFromStatus()。
 */

(() => {
  "use strict";

  // 学习通的课件阅读器会嵌套多个 iframe。用户脚本默认会在每一层都运行，
  // 因而会产生多个悬浮按钮；只允许顶层页面创建唯一的解析面板。
  if (window.top !== window.self) return;

  const STATUS_API = "https://mooc1.chaoxing.com/ananas/status/";
  const CARDS_API = "https://mooc1.chaoxing.com/knowledge/cards";
  const FILE_EXTENSIONS = {
    pdf: "pdf",
    ppt: "ppt",
    pptx: "ppt",
    pps: "ppt",
    ppsx: "ppt",
    doc: "word",
    docx: "word",
    wps: "word",
    xls: "sheet",
    xlsx: "sheet",
    csv: "sheet",
    mp4: "video",
    m3u8: "video",
    flv: "video",
    avi: "video",
    mov: "video",
    mkv: "video",
    zip: "archive",
    rar: "archive",
    "7z": "archive",
  };
  const TYPE_LABELS = {
    pdf: "PDF",
    ppt: "PPT",
    word: "WORD",
    sheet: "表格",
    video: "视频",
    archive: "压缩包",
    file: "文件",
  };

  const state = {
    open: false,
    parsing: false,
    downloading: false,
    resources: [],
    drag: null,
    suppressTabClick: false,
  };
  const TAB_POSITION_KEY = "cxh-tab-position-v1";
  const TAB_MARGIN = 10;
  const TAB_SNAP_STEP = 16;

  function escapeHtml(value) {
    return String(value)
      .replaceAll("&", "&")
      .replaceAll("<", "&lt;")
      .replaceAll(">", "&gt;")
      .replaceAll('"', "&quot;")
      .replaceAll("'", "&#039;");
  }

  function requestJson(url, referer = location.href) {
    return new Promise((resolve, reject) => {
      GM_xmlhttpRequest({
        method: "GET",
        url,
        responseType: "json",
        timeout: 30_000,
        headers: { Referer: referer },
        onload(response) {
          if (response.status >= 200 && response.status < 300) {
            resolve(response.response);
          } else {
            reject(new Error(`HTTP ${response.status}`));
          }
        },
        onerror: () => reject(new Error("网络请求失败")),
        ontimeout: () => reject(new Error("请求超时")),
      });
    });
  }

  function parseMArgText(text) {
    const match = text.match(/mArg\s*=\s*(\{[\s\S]*?\});\s*(?:\n|<\/script>)/);
    if (!match) return null;
    try {
      return JSON.parse(match[1]);
    } catch {
      return null;
    }
  }

  function pageMArg() {
    try {
      if (typeof unsafeWindow !== "undefined" && unsafeWindow.mArg) return unsafeWindow.mArg;
    } catch {
      // 某些脚本管理器隔离页面变量，继续从 HTML 中读取。
    }
    for (const script of document.scripts) {
      const value = parseMArgText(script.textContent || "");
      if (value) return value;
    }
    return null;
  }

  function valueFromPage(names) {
    const search = new URLSearchParams(location.search);
    for (const name of names) {
      const queryValue = search.get(name);
      if (queryValue) return queryValue;
      const element = document.querySelector(`[name="${name}"], #${name}`);
      if (element && "value" in element && element.value) return element.value;
    }
    return "";
  }

  function chapterContext() {
    return {
      courseid: valueFromPage(["courseid", "courseId"]),
      clazzid: valueFromPage(["clazzid", "clazzId"]),
      knowledgeid: valueFromPage(["knowledgeid", "knowledgeId", "chapterId"]),
      cpi: valueFromPage(["cpi"]),
    };
  }

  async function getAttachments() {
    const mArg = pageMArg();
    if (Array.isArray(mArg?.attachments) && mArg.attachments.length) return mArg.attachments;

    // 有些章节内容在 iframe 或异步加载，顶层页面没有 mArg；此时复用原项目的 cards 回退接口。
    const context = chapterContext();
    if (!context.courseid || !context.clazzid || !context.knowledgeid || !context.cpi) {
      throw new Error("未读到本章课程参数。请进入具体章节的课件页面后再解析。");
    }
    const query = new URLSearchParams({
      clazzid: context.clazzid,
      courseid: context.courseid,
      knowledgeid: context.knowledgeid,
      num: "0",
      ut: "s",
      cpi: context.cpi,
      v: "2025-0424-1038-4",
      mooc2: "1",
      isMicroCourse: "false",
      editorPreview: "0",
    });
    const html = await new Promise((resolve, reject) => {
      GM_xmlhttpRequest({
        method: "GET",
        url: `${CARDS_API}?${query}`,
        timeout: 30_000,
        headers: { Referer: location.href },
        onload(response) {
          if (response.status >= 200 && response.status < 300) resolve(response.responseText);
          else reject(new Error(`章节信息请求失败：HTTP ${response.status}`));
        },
        onerror: () => reject(new Error("章节信息请求失败")),
      });
    });
    const cardsMArg = parseMArgText(html);
    if (!Array.isArray(cardsMArg?.attachments)) throw new Error("该章节未返回可解析的附件信息。");
    return cardsMArg.attachments;
  }

  function extensionOf(value) {
    const path = String(value).split("?")[0].split("#")[0];
    return (path.match(/\.([a-z0-9]{1,8})$/i)?.[1] || "").toLowerCase();
  }

  function inferKind(name, url, attachmentType) {
    const extension = extensionOf(name) || extensionOf(url);
    if (FILE_EXTENSIONS[extension]) return FILE_EXTENSIONS[extension];
    const type = String(attachmentType || "").toLowerCase();
    if (type.includes("video")) return "video";
    if (type.includes("pdf")) return "pdf";
    if (type.includes("ppt")) return "ppt";
    if (type.includes("word") || type.includes("doc")) return "word";
    return "file";
  }

  function safeFileName(name, url, kind) {
    let result = String(name || "课件").replace(/[<>:"/\\|?*\x00-\x1F]/g, "_").trim();
    if (!extensionOf(result)) {
      const extension = extensionOf(url) || ({ pdf: "pdf", ppt: "ppt", word: "docx", video: "mp4" }[kind] || "");
      if (extension) result += `.${extension}`;
    }
    return result || "课件";
  }

  function resourceFromStatus(attachment, status) {
    const property = attachment.property || {};
    const objectId = property.objectid || property.objectId || attachment.objectid || attachment.objectId;
    const name = property.name || attachment.name || objectId || "未命名课件";
    const attachmentType = attachment.type || property.type || "";
    const candidates = [status?.pdf, status?.download, status?.http];
    const url = candidates.find((value) => typeof value === "string" && /^https?:\/\//i.test(value));
    if (!url) return null;
    const kind = inferKind(name, url, attachmentType);
    return {
      id: `${objectId || name}:${url}`,
      objectId,
      name: safeFileName(name, url, kind),
      url,
      kind,
      selected: true,
    };
  }

  function selectedResources() {
    return state.resources.filter((resource) => resource.selected);
  }

  function setStatus(message, tone = "") {
    const status = document.querySelector("#cxh-status");
    if (!status) return;
    status.className = `cxh-status ${tone}`;
    status.textContent = message;
  }

  function renderResults() {
    const list = document.querySelector("#cxh-results");
    const count = document.querySelector("#cxh-count");
    const download = document.querySelector("#cxh-download");
    if (!list || !count || !download) return;

    count.textContent = `${state.resources.length} 个文件`;
    download.disabled = state.downloading || selectedResources().length === 0;
    download.textContent = state.downloading ? "下载中…" : `下载选中（${selectedResources().length}）`;

    if (!state.resources.length) {
      list.innerHTML = '<p class="cxh-empty">解析后将在这里列出文件</p>';
      return;
    }
    list.innerHTML = state.resources.map((resource, index) => `
      <label class="cxh-item" title="${escapeHtml(resource.name)}">
        <input class="cxh-check" type="checkbox" data-index="${index}" ${resource.selected ? "checked" : ""}>
        <span class="cxh-kind cxh-kind-${resource.kind}">${TYPE_LABELS[resource.kind] || "文件"}</span>
        <span class="cxh-name">${escapeHtml(resource.name)}</span>
      </label>
    `).join("");
    list.querySelectorAll(".cxh-check").forEach((checkbox) => {
      checkbox.addEventListener("change", (event) => {
        const index = Number(event.currentTarget.dataset.index);
        state.resources[index].selected = event.currentTarget.checked;
        renderResults();
      });
    });
  }

  function setOpen(open) {
    state.open = open;
    const root = document.querySelector("#cxh-root");
    const tab = document.querySelector("#cxh-tab");
    if (!root || !tab) return;
    root.classList.toggle("cxh-open", open);
    tab.setAttribute("aria-expanded", String(open));
  }

  function clamp(value, minimum, maximum) {
    return Math.min(Math.max(value, minimum), maximum);
  }

  function tabTopRange(root) {
    const max = Math.max(TAB_MARGIN, window.innerHeight - root.offsetHeight - TAB_MARGIN);
    return { min: TAB_MARGIN, max };
  }

  function savedTabRatio() {
    try {
      const value = Number.parseFloat(localStorage.getItem(TAB_POSITION_KEY) || "");
      return Number.isFinite(value) ? clamp(value, 0, 1) : 0.5;
    } catch {
      return 0.5;
    }
  }

  function setTabTop(root, top, persist = false) {
    const range = tabTopRange(root);
    const safeTop = clamp(top, range.min, range.max);
    root.style.top = `${safeTop}px`;
    root.style.transform = "none";
    if (!persist) return;

    const ratio = range.max === range.min ? 0 : (safeTop - range.min) / (range.max - range.min);
    try {
      localStorage.setItem(TAB_POSITION_KEY, String(ratio));
    } catch {
      // 隐私模式或站点策略禁用 localStorage 时，仍可在当前页面拖动。
    }
  }

  function restoreTabPosition(root) {
    const range = tabTopRange(root);
    setTabTop(root, range.min + (range.max - range.min) * savedTabRatio());
  }

  function snapTabTop(root, top) {
    const range = tabTopRange(root);
    const snapped = range.min + Math.round((top - range.min) / TAB_SNAP_STEP) * TAB_SNAP_STEP;
    return clamp(snapped, range.min, range.max);
  }

  function bindTabDrag(root) {
    const tab = root.querySelector("#cxh-tab");

    tab.addEventListener("pointerdown", (event) => {
      if (event.button !== 0 && event.pointerType !== "touch") return;
      const rect = root.getBoundingClientRect();
      // 将初始的 50% + translate 位置转换为像素位置，拖动时不会跳动。
      setTabTop(root, rect.top);
      state.drag = {
        pointerId: event.pointerId,
        startY: event.clientY,
        startTop: rect.top,
        moved: false,
      };
      tab.setPointerCapture?.(event.pointerId);
    });

    tab.addEventListener("pointermove", (event) => {
      const drag = state.drag;
      if (!drag || drag.pointerId !== event.pointerId) return;
      const offset = event.clientY - drag.startY;
      if (Math.abs(offset) > 4) drag.moved = true;
      if (!drag.moved) return;
      setTabTop(root, drag.startTop + offset);
      event.preventDefault();
    });

    const finishDrag = (event) => {
      const drag = state.drag;
      if (!drag || drag.pointerId !== event.pointerId) return;
      if (drag.moved) {
        const currentTop = root.getBoundingClientRect().top;
        setTabTop(root, snapTabTop(root, currentTop), true);
        // pointerup 后仍可能触发 click；阻止这次 click 以保持原有展开状态。
        state.suppressTabClick = true;
      }
      state.drag = null;
      if (tab.hasPointerCapture?.(event.pointerId)) tab.releasePointerCapture(event.pointerId);
    };

    tab.addEventListener("pointerup", finishDrag);
    tab.addEventListener("pointercancel", finishDrag);
    window.addEventListener("resize", () => restoreTabPosition(root));
  }

  function bindOutsideDismiss(root) {
    // 顶层页面自身的内容区域：点击悬浮书签和下载框之外即收起。
    document.addEventListener("pointerdown", (event) => {
      if (state.open && !root.contains(event.target)) setOpen(false);
    }, true);

    // 学习通的课件正文通常在 iframe 中，iframe 内部的点击不会冒泡到顶层文档；
    // 点击后顶层窗口会失焦，因此在焦点转入 iframe 时同样收起面板。
    window.addEventListener("blur", () => {
      window.setTimeout(() => {
        if (state.open && document.activeElement?.tagName === "IFRAME") setOpen(false);
      }, 0);
    });
  }

  async function parseCourseware() {
    if (state.parsing) return;
    state.parsing = true;
    const button = document.querySelector("#cxh-parse");
    button.disabled = true;
    button.textContent = "解析中…";
    state.resources = [];
    renderResults();
    setStatus("正在读取本章附件…");

    try {
      const attachments = await getAttachments();
      setStatus(`正在解析 ${attachments.length} 个附件…`);
      const parsed = await Promise.all(attachments.map(async (attachment) => {
        const property = attachment.property || {};
        const objectId = property.objectid || property.objectId || attachment.objectid || attachment.objectId;
        if (!objectId) return null;
        try {
          const status = await requestJson(`${STATUS_API}${encodeURIComponent(objectId)}?flag=normal`);
          return resourceFromStatus(attachment, status);
        } catch (error) {
          console.warn("[学习通课件解析助手] 附件解析失败", objectId, error);
          return null;
        }
      }));
      const seen = new Set();
      state.resources = parsed.filter((resource) => resource && !seen.has(resource.url) && seen.add(resource.url));
      renderResults();
      setStatus(state.resources.length ? `已找到 ${state.resources.length} 个可下载文件。` : "未找到可下载文件。", state.resources.length ? "success" : "warning");
    } catch (error) {
      setStatus(error.message || "解析失败，请刷新章节页面后重试。", "error");
    } finally {
      state.parsing = false;
      button.disabled = false;
      button.textContent = "一键解析本章课件";
    }
  }

  function downloadOne(resource) {
    return new Promise((resolve, reject) => {
      GM_download({
        url: resource.url,
        name: resource.name,
        saveAs: false,
        onload: resolve,
        onerror: reject,
        ontimeout: reject,
      });
    });
  }

  const delay = (milliseconds) => new Promise((resolve) => setTimeout(resolve, milliseconds));

  async function downloadSelected() {
    if (state.downloading) return;
    const resources = selectedResources();
    if (!resources.length) return;
    state.downloading = true;
    renderResults();
    let failed = 0;

    for (let index = 0; index < resources.length; index += 1) {
      setStatus(`正在下载 ${index + 1}/${resources.length}：${resources[index].name}`);
      try {
        await downloadOne(resources[index]);
      } catch (error) {
        failed += 1;
        console.warn("[学习通课件解析助手] 下载失败", resources[index], error);
      }
      // 避免浏览器把连续下载判定为异常弹窗。
      await delay(180);
    }

    state.downloading = false;
    renderResults();
    setStatus(failed ? `下载完成，${failed} 个文件失败。` : `已提交 ${resources.length} 个文件到浏览器下载。`, failed ? "warning" : "success");
  }

  function createUi() {
    if (document.querySelector("#cxh-root")) return;
    const root = document.createElement("aside");
    root.id = "cxh-root";
    root.innerHTML = `
      <style>
        #cxh-root { position: fixed; z-index: 2147483647; left: 0; top: 50%; transform: translateY(-50%); font: 14px/1.45 -apple-system, BlinkMacSystemFont, "Microsoft YaHei", sans-serif; color: #24324a; }
        #cxh-root *, #cxh-root *::before, #cxh-root *::after { box-sizing: border-box; }
        #cxh-tab { width: 52px; min-height: 96px; border: 0; border-radius: 0 13px 13px 0; background: linear-gradient(155deg, #2769dc, #16449e); color: #fff; box-shadow: 2px 5px 16px #133b803d; cursor: grab; letter-spacing: .12em; font: 600 16px/1.32 "Microsoft YaHei", sans-serif; touch-action: none; user-select: none; transition: background .18s ease; }
        #cxh-tab:hover { background: linear-gradient(155deg, #3479ec, #1a51b6); }
        #cxh-tab:active { cursor: grabbing; }
        .cxh-tab-text { display: grid; grid-template-columns: repeat(2, 1em); justify-content: center; gap: 4px 5px; }
        #cxh-panel { display: none; position: absolute; left: 64px; top: 50%; width: 360px; transform: translateY(-50%); padding: 16px; border: 1px solid #dce6f7; border-radius: 14px; background: #fff; box-shadow: 0 13px 35px #1739652b; }
        #cxh-root.cxh-open #cxh-panel { display: block; animation: cxh-slide .16s ease-out; }
        @keyframes cxh-slide { from { opacity: 0; transform: translate(-8px, -50%); } to { opacity: 1; transform: translate(0, -50%); } }
        .cxh-title { display: flex; align-items: center; justify-content: space-between; margin-bottom: 12px; color: #1e3560; font-weight: 700; }
        .cxh-title small { color: #7e8da7; font-weight: 400; }
        .cxh-primary, .cxh-download { width: 100%; height: 38px; border: 0; border-radius: 8px; color: #fff; background: #2167d4; cursor: pointer; font: 600 14px "Microsoft YaHei", sans-serif; transition: background .16s ease, opacity .16s ease; }
        .cxh-primary:hover, .cxh-download:hover { background: #1554b8; }
        .cxh-primary:disabled, .cxh-download:disabled { cursor: not-allowed; opacity: .55; }
        .cxh-output-head { display: flex; align-items: center; justify-content: space-between; margin-top: 14px; margin-bottom: 7px; color: #5c6c86; font-size: 12px; }
        #cxh-results { height: 188px; margin: 0; overflow-y: auto; border: 1px solid #e2e9f4; border-radius: 9px; background: #f9fbff; scrollbar-color: #aabbd7 transparent; }
        .cxh-empty { margin: 0; padding: 68px 14px; text-align: center; color: #9aa7b9; }
        .cxh-item { display: flex; align-items: center; min-height: 46px; padding: 7px 9px; gap: 8px; border-bottom: 1px solid #e8eef7; cursor: pointer; }
        .cxh-item:last-child { border-bottom: 0; }
        .cxh-item:hover { background: #f0f6ff; }
        .cxh-check { width: 15px; height: 15px; margin: 0; accent-color: #2167d4; flex: 0 0 auto; cursor: pointer; }
        .cxh-kind { min-width: 37px; padding: 2px 4px; border-radius: 4px; background: #e8eef9; color: #506b98; text-align: center; font-size: 10px; font-weight: 700; }
        .cxh-kind-pdf { background: #fde9ea; color: #b73b46; }.cxh-kind-ppt { background: #fff0df; color: #c57016; }.cxh-kind-word { background: #e5f0ff; color: #286ac6; }.cxh-kind-video { background: #e7f8f2; color: #18875e; }
        .cxh-name { overflow: hidden; color: #3d4f6e; text-overflow: ellipsis; white-space: nowrap; }
        .cxh-status { min-height: 20px; margin: 10px 1px 0; color: #78879d; font-size: 12px; }.cxh-status.success { color: #17815d; }.cxh-status.warning { color: #b87817; }.cxh-status.error { color: #bd3c48; }
        .cxh-download { margin-top: 13px; background: #1eaa78; }.cxh-download:hover { background: #148b61; }
      </style>
      <button id="cxh-tab" type="button" aria-label="展开课件解析" aria-expanded="false"><span class="cxh-tab-text"><span>课</span><span>件</span><span>解</span><span>析</span></span></button>
      <section id="cxh-panel" aria-label="课件解析面板">
        <div class="cxh-title"><span>本章课件解析</span><small>点击左侧书签收起</small></div>
        <button id="cxh-parse" class="cxh-primary" type="button">一键解析本章课件</button>
        <div class="cxh-output-head"><span>解析结果</span><span id="cxh-count">0 个文件</span></div>
        <div id="cxh-results"><p class="cxh-empty">解析后将在这里列出文件</p></div>
        <p id="cxh-status" class="cxh-status">仅解析当前帐号可访问的资源</p>
        <button id="cxh-download" class="cxh-download" type="button" disabled>下载选中（0）</button>
      </section>
    `;
    document.documentElement.appendChild(root);
    const tab = root.querySelector("#cxh-tab");
    tab.addEventListener("click", (event) => {
      if (state.suppressTabClick) {
        state.suppressTabClick = false;
        event.preventDefault();
        return;
      }
      setOpen(!state.open);
    });
    root.querySelector("#cxh-parse").addEventListener("click", parseCourseware);
    root.querySelector("#cxh-download").addEventListener("click", downloadSelected);
    restoreTabPosition(root);
    bindTabDrag(root);
    bindOutsideDismiss(root);
  }

  createUi();
})();