// ==UserScript==
// @name         超星学习通课件下载
// @namespace    https://docs.scriptcat.org/
// @version      1.1
// @description  下载超星学习通课件原文件
// @match        *://*.chaoxing.com/*
// @match        *://pan-yz.chaoxing.com/*
// @icon         http://pan-yz.chaoxing.com/favicon.ico
// @run-at       document-end
// @license    	 MIT
// @noframes
// ==/UserScript==

(() => {
    const ID = 'cx-dl', GAP = 600, DELAY = 800, MAX = 10, DEPTH = 5;
    const isTarget = () => ['/mycourse/studentstudy', '/mooc-ans/knowledge/cards', 'pan-yz.chaoxing.com/screen/file_'].some(p => location.href.includes(p));
    const scan = (doc = document, d = 0) => {
        if (d > DEPTH) return [];
        const r = [];
        try { const w = doc.defaultView || window; if (w?.fileinfo?.download) r.push(w.fileinfo); } catch {/**/}
        for (const f of doc.getElementsByTagName('iframe'))
            try { const w = f.contentWindow; if (w?.fileinfo?.download) r.push(w.fileinfo); if (w?.document) r.push(...scan(w.document, d + 1)); } catch {/**/}
        return r;
    };
    const enableDrag = (el, h) => {
        let sx, sy, ol, ot;
        const mv = e => { e.preventDefault(); el.style.left = Math.max(0, Math.min(ol + e.clientX - sx, innerWidth - el.offsetWidth)) + 'px'; el.style.top = Math.max(0, Math.min(ot + e.clientY - sy, innerHeight - el.offsetHeight)) + 'px'; };
        const up = e => { h.releasePointerCapture(e.pointerId); h.removeEventListener('pointermove', mv); h.removeEventListener('pointerup', up); h.removeEventListener('pointercancel', up); };
        h.addEventListener('pointerdown', e => {
            e.preventDefault(); sx = e.clientX; sy = e.clientY;
            const r = el.getBoundingClientRect(); ol = r.left; ot = r.top;
            el.style.cssText += ';transition:none;right:auto;bottom:auto'; el.style.left = ol + 'px'; el.style.top = ot + 'px';
            h.setPointerCapture(e.pointerId); h.addEventListener('pointermove', mv); h.addEventListener('pointerup', up); h.addEventListener('pointercancel', up);
        });
    };
    const render = list => {
        document.getElementById(ID)?.remove();
        const seen = new Set(), files = list.filter(f => f.download && !seen.has(f.download) && seen.add(f.download));
        if (!files.length) return;
        const el = document.createElement('div'); el.id = ID;
        el.innerHTML = `<style>#${ID}{display:flex;position:fixed;bottom:18%;right:3%;z-index:2147483647;background:#f5f5f5;border-radius:6px;box-shadow:0 1px 5px rgba(0,0,0,.12);border:1px solid #dcdcdc;overflow:hidden}#${ID} .h{padding:0 6px;cursor:move;user-select:none;touchAction:none;color:#3A8BFF;display:flex;align-items:center;font-size:12px}#${ID} .c{display:flex;flex-direction:column;border-left:1px solid #bbb}#${ID} a{display:block;padding:8px 14px;color:#000;font:600 13px/1.4 system-ui,sans-serif;text-decoration:none}#${ID} a+a{border-top:1px solid #bbb}</style><div class="h">⣿</div><div class="c">${files.map((f, i) => `<a href="${f.download}" target="_blank">⇩ 下载资源 ${i + 1}</a>`).join('')}</div>`;
        enableDrag(el, el.querySelector('.h'));
        document.body.appendChild(el);
    };
    let timer;
    const start = () => { clearTimeout(timer); let n = 0; const tick = () => { const r = scan(); if (r.length) render(r); else if (++n < MAX) timer = setTimeout(tick, GAP); }; timer = setTimeout(tick, DELAY); };
    const reset = () => { document.getElementById(ID)?.remove(); clearTimeout(timer); start(); };
    if (!isTarget()) return;
    new MutationObserver(ml => {
        for (const m of ml) {
            if (m.target.id === ID) return;
            if (m.type === 'attributes' && m.attributeName === 'src' && m.target.nodeName === 'IFRAME') return reset();
            if (m.addedNodes.length && [...m.addedNodes].some(n => n.nodeName === 'IFRAME' || [...(n.children || [])].some(c => c.nodeName === 'IFRAME'))) return reset();
        }
    }).observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['src'] });
    reset();
})();