// ==UserScript==
// @name         Deepseek网页输入框草稿留存
// @namespace    https://scriptcat.org/zh-CN/users/214553
// @version      1.0.0
// @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、退出浏览器等文本丢失焦虑。也可用以暂时留存预发送文本(14天)。
// @author       English3
// @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;   // ≈3s，覆盖 React 慢挂载
  const STABLE_FRAMES  = 3;     // 连续 3 帧值正确视为稳定
  const MAX_WRITES     = 5;     // 单次恢复最多补写 5 次
  const MISS_THRESHOLD = 3;     // 侧边栏连续缺失 N 次判定为删除

  //存储：异常降级到内存 Map（并警告一次）//
  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，刷新将丢失。'),
    memoryStore()
  );
  const session = (() => {
    try { const s = sessionStorage; s.setItem('__t','1'); s.removeItem('__t'); return s; }
    catch { return storage; }
  })();

  //会话 key（带缓存，pathname/hash 不变时零正则）//
  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：优先 name="search"，回退到主区域内可编辑 textarea//
  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 写值（React 受控框）//
  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 合成跟踪//
  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：非空→保存；空→清除//
  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);
  };

  //恢复保护窗口//
  let guardUntil = 0;

  const restore = () => {
    const my = ++token;
    guardUntil = performance.now() + 4000;
    requestAnimationFrame(() => {
      if (my !== token) return;
      flush();
      const target = load(key());
      if (target) writeGuarded(target);
    });
  };

  //SPA 切会话（幂等 hook）//
  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);

  //首次加载//
  restore();

  //发送/程序化清空兜底轮询//
  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);

  //启动清理：14 天未访问//
  (() => {
    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)) 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); });
  })();

  //会话删除检测（已优化：500ms 防抖）//
  const watchSessionDeletion = () => {
    const findSidebar = () => {
      const cands = document.querySelectorAll('aside, [class*="sidebar" i]');
      for (const el of cands) {
        if (el.querySelector('a[href*="/chat/"]')) return el;
      }
      return null;
    };

    const snapshot = sidebar => {
      const s = new Set();
      sidebar.querySelectorAll('a[href*="/chat/"]').forEach(a => {
        const m = (a.getAttribute('href') || '').match(/\/chat\/(?:s\/)?([^/?#]+)/);
        if (m) s.add(m[1]);
      });
      return s;
    };

    const start = sidebar => {
      const known = snapshot(sidebar);
      let initialized = known.size > 0;
      const missCount = new Map();

      const handle = () => {
        const now = snapshot(sidebar);
        if (!initialized) {
          if (now.size) { now.forEach(id => known.add(id)); initialized = true; }
          return;
        }

        known.forEach(id => {
          if (now.has(id)) missCount.set(id, 0);
          else missCount.set(id, (missCount.get(id) || 0) + 1);
        });

        missCount.forEach((cnt, id) => {
          if (cnt >= MISS_THRESHOLD) {
            storage.removeItem(PREFIX + id);
            storage.removeItem(META + id);
            missCount.delete(id);
            known.delete(id);
          }
        });

        now.forEach(id => {
          if (!known.has(id)) { known.add(id); missCount.set(id, 0); }
        });
      };

      // 500ms 防抖：避免 React 重渲染时高频触发 snapshot 导致卡顿
      let scheduled = false;
      let debounceTimer = null;
      const mo = new MutationObserver(() => {
        if (scheduled) return;
        scheduled = true;
        clearTimeout(debounceTimer);
        debounceTimer = setTimeout(() => {
          scheduled = false;
          handle();
        }, 500);
      });
      mo.observe(sidebar, { childList: true, subtree: true });
    };

    let frames = 0;
    const wait = () => {
      const sb = findSidebar();
      if (sb) return start(sb);
      if (++frames < 300) requestAnimationFrame(wait);
    };
    wait();
  };

  addEventListener('load', () => setTimeout(watchSessionDeletion, 500));
})();