import { useMemo } from 'react';
import { useQuery } from '@tanstack/react-query';
import { parseAsString, useQueryState } from 'nuqs';
import { ChevronRight, MapPin } from 'lucide-react';
import { PageHeader } from '../components/layout/PageHeader.js';
import { SiteRoomTree } from '../components/locations/SiteRoomTree.js';
import { BinGrid } from '../components/locations/BinGrid.js';
import { listSites } from '../lib/api/sites.js';
import { listRooms } from '../lib/api/rooms.js';
import { queryKeys } from '../lib/queryKeys.js';
import { useAuth } from '../contexts/AuthContext.js';

export default function Locations() {
  const { user } = useAuth();
  const canEdit = user?.role === 'ADMIN';

  const [siteId, setSiteId] = useQueryState('site', parseAsString);
  const [roomId, setRoomId] = useQueryState('room', parseAsString);

  const handleSite = (id: string) => {
    void setSiteId(id || null);
    void setRoomId(null);
  };
  const handleRoom = (id: string) => {
    void setRoomId(id || null);
  };

  const sites = useQuery({
    queryKey: queryKeys.sites.list({ pageSize: 100 }),
    queryFn: () => listSites({ pageSize: 100 }),
  });
  const rooms = useQuery({
    queryKey: queryKeys.rooms.list({ siteId, pageSize: 100 }),
    queryFn: () => listRooms({ siteId: siteId!, pageSize: 100 }),
    enabled: Boolean(siteId),
  });

  const siteName = useMemo(
    () => sites.data?.data.find((s) => s.id === siteId)?.name,
    [sites.data, siteId],
  );
  const roomName = useMemo(
    () => rooms.data?.data.find((r) => r.id === roomId)?.name,
    [rooms.data, roomId],
  );

  return (
    <div className="flex flex-col gap-4">
      <PageHeader
        title="Locations"
        description="Sites → Rooms → Bins. Pick a room to see its bins."
      />
      <div className="grid grid-cols-[18rem_1fr] overflow-hidden rounded-lg border border-border bg-card">
        <div className="border-r border-border">
          <SiteRoomTree
            siteId={siteId}
            roomId={roomId}
            onSelectSite={handleSite}
            onSelectRoom={handleRoom}
            canEdit={canEdit}
          />
        </div>
        <div className="flex flex-col">
          <Breadcrumb siteName={siteName} roomName={roomName} />
          <div className="flex-1">
            {roomId ? (
              <BinGrid roomId={roomId} canEdit={canEdit} />
            ) : (
              <EmptyPane siteSelected={Boolean(siteId)} />
            )}
          </div>
        </div>
      </div>
    </div>
  );
}

function Breadcrumb({
  siteName,
  roomName,
}: {
  siteName: string | undefined;
  roomName: string | undefined;
}) {
  return (
    <div className="flex items-center gap-1.5 border-b border-border px-4 py-2 text-sm text-muted-foreground">
      {siteName ? (
        <>
          <span className="text-foreground">{siteName}</span>
          {roomName && (
            <>
              <ChevronRight className="h-3.5 w-3.5 opacity-60" />
              <span className="text-foreground">{roomName}</span>
            </>
          )}
        </>
      ) : (
        <span>Select a site to begin.</span>
      )}
    </div>
  );
}

function EmptyPane({ siteSelected }: { siteSelected: boolean }) {
  return (
    <div className="flex h-full items-center justify-center p-8">
      <div className="flex max-w-sm flex-col items-center gap-2 rounded-lg border border-dashed border-border bg-muted/30 px-8 py-10 text-center">
        <MapPin className="h-6 w-6 text-muted-foreground" />
        <p className="text-sm font-medium">
          {siteSelected ? 'Pick a room' : 'Pick a site and room'}
        </p>
        <p className="text-xs text-muted-foreground">
          Bins live inside rooms. Expand a site in the tree and choose a room to manage its bins.
        </p>
      </div>
    </div>
  );
}