import { useState } from 'react';

import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';

import { Icon } from '@/app/Icon';
import { fetchAllPages } from '@/lib/api/client';
import { acceptGroupJoinRequest, getAllGroupMembers, getGroupJoinRequests, rejectGroupJoinRequest, type GroupJoinRequest } from '@/lib/api/groups';
import { avatarBgClass, avatarLetter } from '@/lib/avatar';
import { useEscapeKey } from '@/lib/hooks';
import { formatEventTimestamp } from '@/lib/messages/time';

interface JoinRequestsModalProps {
  topicId: string;
  onClose: () => void;
}

/**
 * README §4.6. Reject sends `{version}` ONLY -- no `reason` field, even though the protocol doc's
 * own example shows one (see lib/api/groups.ts's rejectGroupJoinRequest comment: the old app
 * confirmed live that the real server 400s on an unrecognized `reason` key).
 */
export function JoinRequestsModal({ topicId, onClose }: JoinRequestsModalProps) {
  const queryClient = useQueryClient();
  const [handled, setHandled] = useState<Record<string, 'accepted' | 'rejected'>>({});
  useEscapeKey(onClose);

  const query = useQuery({
    queryKey: ['group-join-requests', topicId],
    // `'pending'`-only used to mean a request resolved before this session (or by another admin)
    // just never appeared here at all -- the render below already has a real "已同意/已拒绝" branch
    // keyed off the server's own `req.status`, it just never got fed anything but pending requests to
    // apply that branch to. README §4.6's own mock shows an already-resolved row persisting in the
    // list, matching `'all'`, not `'pending'`.
    queryFn: () => fetchAllPages<GroupJoinRequest>((cursor) => getGroupJoinRequests(topicId, 'all', cursor)),
  });
  // The applicant themself has no display name anywhere on the real response (see groups.ts's own
  // GroupJoinRequest comment) and isn't a member yet, so there's no list to resolve THEIR name from
  // either -- shown as a bare id, honestly, rather than guessed. The INVITER (mock: "王工 邀请") IS
  // already a member by definition, so that name can be resolved the same way GroupFilesModal's
  // uploader name and GroupAnnouncementModal's author name already do.
  const membersQuery = useQuery({ queryKey: ['group-members', topicId], queryFn: () => getAllGroupMembers(topicId) });
  const memberName = (userId: string) => membersQuery.data?.find((m) => m.user_id === userId)?.display_name || userId;

  const invalidate = () => {
    queryClient.invalidateQueries({ queryKey: ['group-summary', topicId] });
    queryClient.invalidateQueries({ queryKey: ['group-members', topicId] });
    queryClient.invalidateQueries({ queryKey: ['group-members-preview', topicId] });
    queryClient.invalidateQueries({ queryKey: ['group', topicId] });
  };

  const acceptMutation = useMutation({
    mutationFn: (req: GroupJoinRequest) => acceptGroupJoinRequest(topicId, req.request_id, req.version),
    onSuccess: (_data, req) => {
      setHandled((prev) => ({ ...prev, [req.request_id]: 'accepted' }));
      invalidate();
    },
  });

  const rejectMutation = useMutation({
    mutationFn: (req: GroupJoinRequest) => rejectGroupJoinRequest(topicId, req.request_id, req.version),
    onSuccess: (_data, req) => {
      setHandled((prev) => ({ ...prev, [req.request_id]: 'rejected' }));
      // Unlike accept, nothing here changes group membership -- but `group-summary`'s
      // `pending_join_request_count` badge (read by GroupAdminModal's "进群申请" row) does need to
      // drop by one, and this previously invalidated nothing at all, leaving that badge stuck high.
      invalidate();
    },
  });

  return (
    <div className="fixed inset-0 z-50 flex items-center justify-center bg-[#22262d]/25" onClick={onClose}>
      <div className="flex h-[480px] w-[560px] flex-col rounded-xl bg-white shadow-modal" onClick={(e) => e.stopPropagation()}>
        <header className="flex h-14 flex-none items-center justify-between border-b border-border-list-item px-5">
          <strong className="text-[15px] font-semibold text-text-heading">进群申请</strong>
          <button type="button" onClick={onClose} className="grid h-8 w-8 place-items-center text-text-tertiary-4">
            <Icon name="close" />
          </button>
        </header>
        <div className="flex-1 overflow-y-auto px-2 py-2">
          {query.isLoading ? (
            <div className="py-10 text-center text-sm text-text-tertiary-4">加载中…</div>
          ) : !query.data?.length ? (
            <div className="py-10 text-center text-sm text-text-tertiary-4">暂无进群申请</div>
          ) : (
            query.data.map((req) => {
              const status = handled[req.request_id];
              return (
                <div key={req.request_id} className="flex items-center gap-3 px-3 py-2.5">
                  <span className={`grid h-11 w-11 flex-none place-items-center rounded-lg text-base font-medium text-white ${avatarBgClass(req.user_id)}`}>
                    {avatarLetter(req.user_id)}
                  </span>
                  <span className="flex min-w-0 flex-1 flex-col">
                    <strong className="truncate text-sm font-medium text-text-body">{req.user_id}</strong>
                    <span className="truncate text-xs text-text-tertiary-2">
                      {/* mock (#1c): "{邀请人} 邀请" when invited, else a source label -- NOT
                          `source==='qr' ? ... : 邀请`, which used to show "邀请" for every
                          non-qr source including a plain self-initiated search request that
                          nobody actually invited (confirmed live: `source` really does take a
                          `"search"` value distinct from an invite). `inviter_id` is the real
                          signal for "was this an invite", not `source`. */}
                      {req.inviter_id ? `${memberName(req.inviter_id)} 邀请` : req.source === 'qr' ? '扫码申请' : '申请加入'}
                      {req.message ? ` · "${req.message}"` : ''} · {formatEventTimestamp(new Date(req.created_at))}
                    </span>
                  </span>
                  {status || req.status !== 'pending' ? (
                    <span className="flex-none text-xs text-text-tertiary-3">
                      {status === 'accepted' || req.status === 'accepted' ? '已同意' : '已拒绝'}
                    </span>
                  ) : (
                    <span className="flex flex-none items-center gap-2">
                      <button
                        type="button"
                        onClick={() => rejectMutation.mutate(req)}
                        disabled={acceptMutation.isPending || rejectMutation.isPending}
                        className="h-8 rounded-lg border border-[#d5d9df] px-3 text-xs text-text-secondary disabled:opacity-50"
                      >
                        拒绝
                      </button>
                      <button
                        type="button"
                        onClick={() => acceptMutation.mutate(req)}
                        disabled={acceptMutation.isPending || rejectMutation.isPending}
                        className="h-8 rounded-lg bg-btn px-3 text-xs font-medium text-white disabled:bg-btn-disabled"
                      >
                        同意
                      </button>
                    </span>
                  )}
                </div>
              );
            })
          )}
        </div>
      </div>
    </div>
  );
}