import { useEffect, useRef, useState } from 'react';
import { useMailStore } from '../stores/mailStore';
import { useSessionStore } from '../stores/sessionStore';
import { useUIStore } from '../stores/uiStore';
import type { Mail } from '../types';
import { groupPermissions, type PermissionGroup } from '../lib/mailGroups';
import { ShieldIcon, ChevronRightIcon, CheckIcon, CloseIcon, BotIcon } from './icons';

/**
 * 授权列表：一级是会话，二级是该会话的授权请求。
 *
 * 独立于收件箱存在，因为权限请求不是「一封信」而是「一件待办」——
 * 它的生命周期是「等人点头 → 决策完就作废」，混进收件箱两者互相伤害：
 * 一次 Agent 任务能产生十几个权限请求（每个被拦下的 bash/write 都是一封），
 * 把真正需要阅读的来信压到看不见的地方；反过来，人要找「有什么在等我批」
 * 也得在几十封信里翻。生产实测一个会话独占 17 封权限邮件。
 */
export default function PermissionList() {
  const inbox = useMailStore(s => s.inbox);
  const currentMail = useMailStore(s => s.currentMail);
  const selectMail = useMailStore(s => s.selectMail);
  const fetchInbox = useMailStore(s => s.fetchInbox);
  const clearSession = useSessionStore(s => s.clearSession);
  const cancelCompose = useUIStore(s => s.cancelCompose);
  const showDetail = useUIStore(s => s.showDetail);

  const groups = groupPermissions(inbox);
  const pendingTotal = groups.reduce((n, g) => n + g.pending.length, 0);

  // 有待决策请求的会话默认展开：那些是在等人动手的，藏起来等于没解决问题。
  // 全部已决策的会话默认折叠 —— 它们只是历史。
  const [expanded, setExpanded] = useState<Set<string> | null>(null);
  const autoOpen = groups.filter(g => g.pending.length > 0).map(g => g.sessionId);
  const openSet = expanded ?? new Set(autoOpen);

  /**
   * 新到手的待决请求必须让它所在的会话**自己打开**。
   *
   * 为什么需要这一段：`expanded` 一旦被手动点过一次，`expanded ?? autoOpen`
   * 就永远取前者 —— 那份快照冻结在"点的那一刻"。此后新到的待决请求会落在
   * 一个折叠的分组里：**徽标数字变了，内容却看不见**，直到离开再回到授权页
   * （组件重挂载、`expanded` 回到 null、默认展开重算）才出现。
   * 线上实测复现过：授权 2 → 3 而新请求正文不可见，重进页面才可见。
   *
   * 判据是**新出现的待决邮件**（`sessionId:mailId`），不是"会话有没有待决"：
   * 会话早就有待决、用户把它折叠了，之后**又来了新的一条** —— 那一条同样必须
   * 露出来（这正是实测里撞到的情形）。而用户在这之后对同一条的折叠不会被弹开，
   * 因为没有新的 mail_id 出现。
   */
  const pendingKey = groups
    .flatMap(g => g.pending.map(m => `${g.sessionId}:${m.mail_id}`))
    .sort()
    .join(',');
  const prevPendingRef = useRef<string>('');
  useEffect(() => {
    const prev = new Set(prevPendingRef.current ? prevPendingRef.current.split(',') : []);
    prevPendingRef.current = pendingKey;
    const newly = (pendingKey ? pendingKey.split(',') : []).filter(k => !prev.has(k));
    if (newly.length === 0) return;
    const sessions = Array.from(new Set(newly.map(k => k.split(':')[0])));
    // expanded === null 时本来就走 autoOpen，不需要动
    setExpanded(prevSet => (prevSet === null ? prevSet : new Set([...prevSet, ...sessions])));
  }, [pendingKey]);

  useEffect(() => {
    fetchInbox('all');
  }, []);

  const toggle = (sessionId: string) => {
    setExpanded(prev => {
      const next = new Set(prev ?? autoOpen);
      if (next.has(sessionId)) next.delete(sessionId);
      else next.add(sessionId);
      return next;
    });
  };

  const pick = (m: Mail) => {
    clearSession();
    cancelCompose();
    selectMail(m);
    showDetail();
  };

  return (
    <div className="w-full lg:w-[340px] shrink-0 border-r border-gray-200 bg-white flex flex-col min-w-0">
      <div className="px-4 py-3 border-b border-gray-200 flex items-center gap-1">
        <h2 className="text-sm font-semibold text-gray-800">授权</h2>
        {pendingTotal > 0 ? (
          <span className="ml-2 inline-flex items-center gap-0.5 px-1.5 py-0.5 rounded-full bg-orange-100 text-orange-700 text-3xs font-semibold">
            <ShieldIcon className="w-2.5 h-2.5" />
            {pendingTotal} 待决策
          </span>
        ) : (
          <span className="ml-2 text-xs text-gray-400">
            {groups.length > 0 ? `${groups.length} 个会话` : ''}
          </span>
        )}
      </div>

      <div className="flex-1 overflow-y-auto p-2 space-y-1">
        {groups.map(g => (
          <PermissionSessionGroup
            key={g.sessionId}
            group={g}
            open={openSet.has(g.sessionId)}
            onToggle={() => toggle(g.sessionId)}
            currentMailID={currentMail?.mail_id}
            onPick={pick}
          />
        ))}

        {groups.length === 0 && (
          <div className="text-center py-10">
            <ShieldIcon className="w-8 h-8 mx-auto text-gray-300" />
            <p className="text-xs text-gray-400 mt-2">没有授权请求</p>
            <p className="text-3xs text-gray-500 mt-1 px-6">
              Agent 执行敏感操作（bash、写文件）时会在这里请求你批准
            </p>
          </div>
        )}
      </div>
    </div>
  );
}

/** 一个会话的授权组：组头显示 Agent 与待决策数，展开后是逐条请求。 */
function PermissionSessionGroup({
  group: g,
  open,
  onToggle,
  currentMailID,
  onPick
}: {
  group: PermissionGroup;
  open: boolean;
  onToggle: () => void;
  currentMailID?: string;
  onPick: (m: Mail) => void;
}) {
  const [showSettled, setShowSettled] = useState(false);
  const hasPending = g.pending.length > 0;
  const time = new Date(g.latest.created_at).toLocaleString('zh-CN', {
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit'
  });

  return (
    <div
      className={`rounded-lg border ${
        hasPending ? 'border-orange-200 bg-orange-50/50' : 'border-gray-100'
      }`}
    >
      <button onClick={onToggle} className="w-full text-left px-3 py-2.5 rounded-lg">
        <div className="flex items-center gap-1.5">
          <ChevronRightIcon
            className={`w-3 h-3 text-gray-400 shrink-0 transition-transform ${
              open ? 'rotate-90' : ''
            }`}
          />
          <BotIcon className="w-3.5 h-3.5 text-slate-600 shrink-0" />
          <span className="text-xs font-mono text-gray-900 truncate">
            {g.agentName}{g.path ? `@${g.path}` : ''}{g.alias ? `.${g.alias}` : ''}
          </span>
          <span className="ml-auto text-3xs text-gray-500 shrink-0">{time}</span>
        </div>

        <div className="flex items-center gap-1.5 mt-1 pl-5">
          {hasPending ? (
            <span className="shrink-0 inline-flex items-center gap-0.5 px-1.5 py-0.5 rounded bg-orange-700 text-white text-3xs font-bold">
              <ShieldIcon className="w-2.5 h-2.5" />
              {g.pending.length} 待决策
            </span>
          ) : (
            <span className="shrink-0 inline-flex items-center gap-0.5 px-1 py-0.5 rounded bg-gray-100 text-gray-500 text-3xs">
              <CheckIcon className="w-2.5 h-2.5" />
              已全部处理
            </span>
          )}
          {g.settled.length > 0 && (
            <span className="text-3xs text-gray-500">历史 {g.settled.length}</span>
          )}
        </div>

        {!g.alias && (
          <p className="text-3xs text-gray-500 font-mono truncate mt-0.5 pl-5">
            (未命名会话)
          </p>
        )}
      </button>

      {open && (
        <div className="px-2 pb-2 space-y-0.5">
          {g.pending.map(m => (
            <PermissionRow
              key={m.mail_id}
              mail={m}
              active={currentMailID === m.mail_id}
              onClick={() => onPick(m)}
            />
          ))}

          {g.settled.length > 0 && (
            <>
              <button
                onClick={() => setShowSettled(v => !v)}
                className="w-full text-left px-2 py-1 text-3xs text-gray-500 hover:text-gray-600"
              >
                {showSettled ? '收起' : '展开'}已决策 {g.settled.length}
              </button>
              {showSettled &&
                g.settled.map(m => (
                  <PermissionRow
                    key={m.mail_id}
                    mail={m}
                    active={currentMailID === m.mail_id}
                    onClick={() => onPick(m)}
                  />
                ))}
            </>
          )}
        </div>
      )}
    </div>
  );
}

/** 一条授权请求。待决策的醒目，已决策的连结果一起显示（批了还是拒了）。 */
function PermissionRow({
  mail,
  active,
  onClick
}: {
  mail: Mail;
  active: boolean;
  onClick: () => void;
}) {
  const settled = !!mail.permission_result;
  const approved = settled && /同意|允许|批准|approve|yes/i.test(mail.permission_result || '');
  // 待办是否已越过等待窗口：拿服务端给的**时刻**与本地当前时间比。
  //
  // 服务端刻意不发「是否失效」的布尔值 —— 那是发出那一刻的快照，经 SSE 缓存到
  // 本地后会永久停在 false，于是界面会把一条早就没人等的待办一直显示成「等待你
  // 决策」。时刻是持久事实，任何时刻都能自己算出结论。
  const expired =
    !settled &&
    !!mail.permission_expires_at &&
    Date.now() > Date.parse(mail.permission_expires_at);
  const time = new Date(mail.created_at).toLocaleString('zh-CN', {
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit'
  });

  return (
    <button
      onClick={onClick}
      className={`w-full text-left px-2.5 py-2 rounded-md border transition-colors ${
        active
          ? 'bg-blue-50 border-blue-200'
          : settled
          ? 'border-transparent hover:bg-gray-50'
          : expired
          // 失效的不该和还能立刻生效的长得一样：它点了也不会恢复原调用。
          ? 'border-gray-200 bg-gray-50 hover:bg-gray-100'
          : 'border-orange-200 bg-white hover:bg-orange-50'
      }`}
    >
      <div className="flex items-center gap-1.5">
        <span
          className={`text-xs truncate flex-1 ${
            settled ? 'text-gray-500' : 'font-medium text-gray-900'
          }`}
        >
          {mail.subject}
        </span>
        <span className="text-3xs text-gray-500 shrink-0">{time}</span>
      </div>
      <div className="flex items-center gap-1 mt-0.5">
        {settled ? (
          <span
            className={`inline-flex items-center gap-0.5 text-3xs ${
              approved ? 'text-green-600' : 'text-red-500'
            }`}
          >
            {approved ? <CheckIcon className="w-2.5 h-2.5" /> : <CloseIcon className="w-2.5 h-2.5" />}
            {mail.permission_result}
          </span>
        ) : expired ? (
          <span
            className="inline-flex items-center gap-0.5 text-3xs text-gray-500"
            title={
              '已超过等待窗口，发起它的 Agent 很可能已不再阻塞等待。' +
              '现在批准不会恢复当时那次工具调用 —— 决策会作为一条通知投给它，让它重起一轮。'
            }
          >
            <ShieldIcon className="w-2.5 h-2.5" />
            可能已失效
          </span>
        ) : (
          <span className="inline-flex items-center gap-0.5 text-3xs text-orange-600 font-medium">
            <ShieldIcon className="w-2.5 h-2.5" />
            等待你决策
          </span>
        )}
      </div>
    </button>
  );
}