import { useState } from 'react';

import { Link, useParams } from 'react-router-dom';

import { Icon } from '@/app/Icon';
import { useBootstrap } from '@/lib/api/hooks';
import { avatarBgClass, avatarLetter } from '@/lib/avatar';
import { formatMessagePreview } from '@/lib/messages/preview';
import { formatListTime } from '@/lib/messages/time';
import { useChatList } from '@/lib/tinode/hooks';
import { useSessionStore } from '@/stores/session';

/**
 * README §2.1's two always-pinned utility rows. Real, confirmed backend facts (docs/IM-前后端对接
 * 文档.md:909): topic names are fixed ("slf"/"sys"), but 系统消息's unread comes from a separate
 * notifications table (not the topic itself) and 文件助手's own dedicated 3-column layout (README
 * §9.2) is Phase 8, not built yet -- so both route to the same SectionPlaceholder-backed "later
 * phase" destinations the rest of the nav already uses (contacts/favorites/calls/settings), rather
 * than a half-working ConversationView that assumes a regular P2P/group contact.
 */
const PINNED_ENTRIES = [
  {
    key: 'system_messages' as const,
    badgeKey: 'system_unread_count' as const,
    label: '系统消息',
    icon: 'notifications',
    route: '/chat/system',
    colorClass: 'bg-warn',
  },
  {
    key: 'file_assistant' as const,
    badgeKey: 'file_assistant_unread_count' as const,
    label: '文件助手',
    icon: 'folder',
    route: '/files',
    colorClass: 'bg-success',
  },
];

/** Chat-list row sort: by `touched` (last activity) descending. Pinned-conversations-first isn't
 *  wired yet -- that's driven by the P2P conversation-settings API (GET/PATCH /conversations/{topic}/
 *  settings {pinned}), which the detail panel doesn't build until its "置顶聊天" toggle lands. */
export function ChatListColumn() {
  const { topicId } = useParams();
  const myUserId = useSessionStore((s) => s.myUserId);
  const contacts = useChatList();
  const bootstrap = useBootstrap();
  const [query, setQuery] = useState('');
  const sorted = [...contacts].sort((a, b) => (b.touched?.getTime() ?? 0) - (a.touched?.getTime() ?? 0));
  const trimmedQuery = query.trim();
  const filtered = trimmedQuery ? sorted.filter((c) => (c.public?.fn || c.topic || '').toLowerCase().includes(trimmedQuery.toLowerCase())) : sorted;
  const pinned = PINNED_ENTRIES.filter((entry) => bootstrap.data?.entries?.[entry.key]?.enabled);

  return (
    <aside className="flex h-full w-full flex-none flex-col border-r border-border-panel bg-white md:w-[300px] lg:w-80">
      <header className="flex h-15 flex-none items-center justify-between px-5">
        <h1 className="m-0 text-xl font-semibold text-text-heading">消息</h1>
        <Icon name="add_comment" className="text-text-heading" />
      </header>
      <div className="mx-3 mb-2.5 flex h-9 items-center rounded-lg bg-surface-search px-3">
        <Icon name="search" className="text-[18px] text-text-placeholder-2" />
        <input
          value={query}
          onChange={(e) => setQuery(e.target.value)}
          placeholder="搜索会话、联系人、消息"
          className="ml-2 w-full bg-transparent text-sm text-text-body outline-none placeholder:text-text-placeholder-2"
        />
      </div>
      <div className="flex flex-1 flex-col overflow-y-auto">
        {pinned.map((entry) => {
          const unread = bootstrap.data?.entry_badges?.[entry.badgeKey] || 0;
          return (
            <Link
              key={entry.key}
              to={entry.route}
              className="grid min-h-[68px] grid-cols-[44px_minmax(0,1fr)_auto] items-center gap-3 border-b border-list-item bg-white px-4 py-2.5 no-underline hover:bg-[#f6f8fb]"
            >
              <span className={`grid h-11 w-11 place-items-center rounded-lg text-white ${entry.colorClass}`}>
                <Icon name={entry.icon} className="text-[22px]" />
              </span>
              <span className="flex min-w-0 flex-col gap-1">
                <strong className="truncate text-[15px] font-medium text-[#272b31]">{entry.label}</strong>
              </span>
              <span className="flex flex-none flex-col items-end justify-between gap-1.5">
                {unread ? (
                  <b className="grid h-[18px] min-w-[18px] place-items-center rounded-full bg-unread px-1.5 text-[11px] font-medium text-white">
                    {unread}
                  </b>
                ) : null}
              </span>
            </Link>
          );
        })}
        {filtered.length === 0 ? (
          <div className="flex flex-1 flex-col items-center justify-center gap-2 text-text-tertiary-4">
            <Icon name={trimmedQuery ? 'search_off' : 'forum'} className="!text-4xl" />
            <span className="text-sm">{trimmedQuery ? '未找到相关会话' : '暂无会话'}</span>
          </div>
        ) : (
          filtered.map((contact) => {
            const name = contact.public?.fn || contact.topic;
            const preview = formatMessagePreview(contact.latestMessage?.(), myUserId);
            const active = topicId === contact.topic;
            return (
              <Link
                key={contact.topic}
                to={`/messages/${contact.topic}`}
                className={`grid min-h-[68px] grid-cols-[44px_minmax(0,1fr)_auto] items-center gap-3 border-b border-list-item px-4 py-2.5 no-underline ${
                  active ? 'bg-accent-selected-bg' : 'bg-white hover:bg-[#f6f8fb]'
                }`}
              >
                <span
                  className={`relative grid h-11 w-11 place-items-center rounded-lg text-base font-medium text-white ${avatarBgClass(contact.topic || '')}`}
                >
                  {avatarLetter(name)}
                  {contact.online ? (
                    <span className="absolute -bottom-0.5 -right-0.5 h-2.5 w-2.5 rounded-full border-2 border-white bg-online" />
                  ) : null}
                </span>
                <span className="flex min-w-0 flex-col gap-1">
                  <span className="flex items-center gap-1.5">
                    <strong className="truncate text-[15px] font-medium text-[#272b31]">{name}</strong>
                  </span>
                  <small className="truncate text-[13px] text-text-tertiary-2">{preview}</small>
                </span>
                <span className="flex flex-none flex-col items-end justify-between gap-1.5">
                  <time className="text-xs text-text-tertiary-3">{contact.touched ? formatListTime(contact.touched) : ''}</time>
                  {contact.unread ? (
                    <b className="grid h-[18px] min-w-[18px] place-items-center rounded-full bg-unread px-1.5 text-[11px] font-medium text-white">
                      {contact.unread}
                    </b>
                  ) : null}
                </span>
              </Link>
            );
          })
        )}
      </div>
    </aside>
  );
}