// ==UserScript==
// @name         Deepseek网页输入框草稿留存
// @namespace    https://scriptcat.org/zh-CN/users/214553
// @version      1.1.0
// @description  独立保存 DeepSeek 网页版每个会话的输入草稿。告别输入内容未发送因误删页面、刷新页面、退出浏览器、意外关机等导致的文本丢失焦虑。也可用以暂时留存预发送文本(14天)。
// @author       English3（Σπg|!εh๑๑๑）
// @license      MIT
// @icon         https://deepseek.com/favicon.ico
// @match        https://chat.deepseek.com/*
// @run-at       document-idle
// @grant        none
// ==/UserScript==

(() => {
  'use strict';

  const PREFIX         = 'ds_draft:';
  const META           = 'ds_draft_ts:';
  const TTL_MS         = 14 * 24 * 3600 * 1000;
  const SAVE_DEBOUNCE  = 250;
  const MAX_FRAMES     = 180;
  const STABLE_FRAMES  = 3;
  const MAX_WRITES     = 5;
  const NAV_POLL_MS    = 150;   // URL 轮询间隔（v1.0.0 的核心兼容利器）

  //存储降级//
  const makeStore = () => {
    try { const s = localStorage; s.setItem('__t','1'); s.removeItem('__t'); return s; }
    catch { return null; }
  };
  const memoryStore = () => {
    const m = new Map();
    return {
      getItem: k => m.has(k) ? m.get(k) : null,
      setItem: (k, v) => m.set(k, v),
      removeItem: k => m.delete(k),
      key: i => [...m.keys()][i],
      get length() { return m.size; },
    };
  };
  const storage = makeStore() || (
    console.warn('[文本框留存] localStorage 不可用，草稿仅保存在内存。'),
    memoryStore()
  );
  const session = (() => {
    try { const s = sessionStorage; s.setItem('__t','1'); s.removeItem('__t'); return s; }
    catch { return storage; }
  })();

  //会话 key//
  let cachedPath = null, cachedKey = '__new__';
  const key = () => {
    const p = location.pathname + location.hash;
    if (p === cachedPath) return cachedKey;
    cachedPath = p;
    const m = p.match(/\/chat\/(?:s\/)?([^\/?#]+)/);
    return (cachedKey = m ? m[1] : '__new__');
  };
  const isNew = k => k === '__new__';
  const src   = k => isNew(k) ? session : storage;

  //定位输入框//
  const TA_SET = new WeakSet();
  const findTA = () => {
    let ta = document.querySelector('textarea[name="search"]');
    if (!ta) ta = document.querySelector('main textarea:not([readonly]):not([disabled])');
    if (ta) TA_SET.add(ta);
    return ta;
  };
  const isTargetTA = el => {
    if (!el || el.tagName !== 'TEXTAREA') return false;
    if (el.name === 'search') return true;
    if (TA_SET.has(el)) return true;
    return el === findTA();
  };

  //原生 setter//
  let internal = false;
  const write = (ta, val) => {
    if (!ta || ta.value === val) return false;
    const set = Object.getOwnPropertyDescriptor(HTMLTextAreaElement.prototype, 'value').set;
    internal = true;
    try { set.call(ta, val); ta.dispatchEvent(new Event('input', { bubbles: true })); }
    finally { internal = false; }
    return true;
  };

  //读写//
  const load = k => { try { return src(k).getItem(PREFIX + k) || ''; } catch { return ''; } };
  const save = (k, v) => {
    try {
      if (v) {
        src(k).setItem(PREFIX + k, v);
        if (!isNew(k)) storage.setItem(META + k, String(Date.now()));
      } else {
        storage.removeItem(PREFIX + k);
        session.removeItem(PREFIX + k);
        storage.removeItem(META + k);
      }
    } catch {}
  };

  //防抖保存//
  let timer = null, pend = null, token = 0;
  const flush = () => {
    clearTimeout(timer); timer = null;
    if (pend) { save(pend.k, pend.v); pend = null; }
  };
  const queue = (k, v) => { pend = { k, v }; clearTimeout(timer); timer = setTimeout(flush, SAVE_DEBOUNCE); };
  const discard = k => { clearTimeout(timer); timer = null; pend = null; save(k, ''); token++; };

  //IME 合成//
  let composing = false;
  document.addEventListener('compositionstart', e => {
    if (isTargetTA(e.target)) composing = true;
  }, true);
  document.addEventListener('compositionend', e => {
    if (!isTargetTA(e.target)) return;
    composing = false;
    if (internal) return;
    const k = key(), v = e.target.value;
    v ? queue(k, v) : discard(k);
  }, true);

  //input 捕获//
  document.addEventListener('input', e => {
    if (internal || composing) return;
    if (!isTargetTA(e.target)) return;
    const k = key(), v = e.target.value;
    v ? queue(k, v) : discard(k);
  }, true);

  addEventListener('beforeunload', flush);
  addEventListener('pagehide', flush);
  document.addEventListener('visibilitychange', () => {
    if (document.visibilityState === 'hidden') flush();
  });

  //帧同步恢复//
  const writeGuarded = val => {
    const my = ++token;
    let frames = 0, stable = 0, writes = 0, cancelled = false;
    let ta = null;

    const onUser = e => {
      if (internal) return;
      if (!isTargetTA(e.target)) return;
      cancelled = true;
    };
    document.addEventListener('input', onUser, true);
    const done = () => document.removeEventListener('input', onUser, true);

    const step = () => {
      if (my !== token || cancelled) return done();
      if (!ta || !ta.isConnected) ta = findTA();

      if (ta) {
        if (ta.value === val) {
          if (++stable >= STABLE_FRAMES) return done();
        } else if (writes < MAX_WRITES) {
          write(ta, val);
          writes++;
          stable = 0;
        } else {
          return done();
        }
      }
      ++frames < MAX_FRAMES ? requestAnimationFrame(step) : done();
    };
    requestAnimationFrame(step);
  };

  //恢复//
  let guardUntil = 0;

  const restore = () => {
    const my = ++token;
    guardUntil = performance.now() + 4000;
    requestAnimationFrame(() => {
      if (my !== token) return;
      flush();
      const k = key();
      const target = load(k);
      if (target) {
        writeGuarded(target);
      } else {
        const ta = findTA();
        if (ta && ta.value) write(ta, '');
      }
    });
  };

  //路由检测：history hook（快）+ URL 轮询（兜底）//
  let lastKey = key();
  const onNav = () => {
    const k = key();
    if (k === lastKey) return;
    lastKey = k;
    restore();
  };

  const NAV_HOOK = Symbol.for('ds_draft_nav_hook');
  if (!history[NAV_HOOK]) {
    history[NAV_HOOK] = true;
    for (const m of ['pushState', 'replaceState']) {
      const orig = history[m];
      history[m] = function (...a) { const r = orig.apply(this, a); onNav(); return r; };
    }
  }
  addEventListener('popstate', onNav);
  addEventListener('hashchange', onNav);

  setInterval(() => {
    const k = key();
    if (k !== lastKey) onNav();
  }, NAV_POLL_MS);

  //首次加载//
  restore();

  //发送/程序化清空兜底//
  setInterval(() => {
    if (performance.now() < guardUntil) return;
    if (document.visibilityState !== 'visible') return;
    const ta = findTA();
    if (!ta) return;
    const k = key();
    const saved = load(k);
    if (saved && ta.value === '') discard(k);
  }, 1000);

  //14 天 TTL 清理//
  (() => {
    const now = Date.now(), stale = [];
    for (let i = 0; i < storage.length; i++) {
      const k = storage.key(i);
      if (!k || !k.startsWith(PREFIX)) continue;
      const cid = k.slice(PREFIX.length);
      if (isNew(cid) || !cid) continue;
      const ts = parseInt(storage.getItem(META + cid) || '0', 10);
      if (!ts || now - ts > TTL_MS) stale.push(cid);
    }
    stale.forEach(cid => { storage.removeItem(PREFIX + cid); storage.removeItem(META + cid); });
  })();
})();