import { useCallback, useEffect, useRef, useState } from 'react';
import { useSearchParams } from 'react-router';
import { useClient } from 'hooks/useClient';
import { Input } from '@/components/ui/input';
import { ExternalLink, FileText } from 'lucide-react';
import { ALL } from './CollectionsPanel';

/**
 * Your saved links, as the calling Officer user.
 *
 * Every request goes through `/api/linkwarden/api/*` — the authenticated door, which finds the caller's
 * mapped account and puts THEIR token on the request. This panel holds no credential and could not send
 * one if it wanted to, which is the property the whole plugin exists for.
 *
 * ── Search is Linkwarden's, not ours ──
 *
 * `searchQueryString` searches names, descriptions, tags AND the archived page text, which is the thing
 * a bookmark bar cannot do. Re-implementing it here would mean pulling every link to the browser to
 * filter it, and would still only see the fields we happened to fetch. Verified against the live
 * instance: 50 links unfiltered, 8 for "arch", 0 for a string that matches nothing.
 */
type Link = {
  id: number;
  name: string;
  url: string;
  description?: string;
  textContent?: string;
  collection?: { id: number; name: string };
  tags?: { id: number; name: string }[];
  createdAt?: string;
};

export const LinksPanel = () => {
  const client = useClient();
  const clientRef = useRef(client);
  clientRef.current = client;

  const [params] = useSearchParams();
  const collection = params.get('collection') ?? ALL;

  const [query, setQuery] = useState('');
  const [rows, setRows] = useState<Link[] | null>(null);
  const [error, setError] = useState<string | null>(null);

  const load = useCallback(async (collectionId: string, search: string) => {
    const qs = new URLSearchParams();
    if (collectionId !== ALL) qs.set('collectionId', collectionId);
    if (search.trim()) qs.set('searchQueryString', search.trim());

    try {
      const body = await clientRef.current.get<{ response: Link[] }>(
        `/linkwarden/api/v1/links${qs.toString() ? `?${qs}` : ''}`,
      );
      setRows(body.response ?? []);
      setError(null);
    } catch (failure) {
      setError(failure instanceof Error ? failure.message : 'Could not read your links.');
      setRows(null);
    }
  }, []);

  /*
    Debounced, because this types straight into a request.

    250 ms is chosen against what it is: somebody typing a word, who wants the list to move while they
    type rather than after they stop. Long enough that a five-letter word is one query instead of five.
  */
  useEffect(() => {
    const timer = setTimeout(() => void load(collection, query), 250);
    return () => clearTimeout(timer);
  }, [collection, query, load]);

  return (
    <div className="flex size-full flex-col">
      <header className="border-b p-2">
        <Input
          value={query}
          onChange={(event) => setQuery(event.target.value)}
          placeholder="Search names, tags and the text of saved pages…"
          className="h-8 text-xs"
        />
      </header>

      {error && (
        <p className="px-3 py-2 text-xs text-destructive">
          {error}
          {/* The state every user starts in, said as an instruction rather than a failure. */}
          {error.includes('no Linkwarden account') && ' — the owner maps accounts in Settings.'}
        </p>
      )}

      {rows === null && !error ? (
        <Centred>Loading…</Centred>
      ) : rows && rows.length === 0 ? (
        <Centred>{query.trim() ? `Nothing matches “${query.trim()}”.` : 'Nothing saved here yet.'}</Centred>
      ) : (
        <ul className="flex-1 divide-y overflow-auto">
          {rows?.map((link) => (
            <li key={link.id} className="group px-3 py-2 hover:bg-muted/40">
              <div className="flex items-start gap-2">
                <FileText className="mt-0.5 size-3.5 shrink-0 text-muted-foreground" />
                <div className="min-w-0 flex-1">
                  <a
                    href={link.url}
                    target="_blank"
                    rel="noreferrer noopener"
                    className="flex items-center gap-1 text-xs hover:underline"
                  >
                    <span className="min-w-0 truncate">{link.name || link.url}</span>
                    <ExternalLink className="size-3 shrink-0 opacity-0 transition-opacity group-hover:opacity-60" />
                  </a>
                  <p className="truncate text-[11px] text-muted-foreground">{link.url}</p>

                  {(link.collection || link.tags?.length) && (
                    <p className="mt-0.5 flex flex-wrap items-center gap-1 text-[10px] text-muted-foreground">
                      {link.collection && <span>{link.collection.name}</span>}
                      {link.tags?.map((tag) => (
                        <span key={tag.id} className="rounded bg-muted px-1 py-px">
                          {tag.name}
                        </span>
                      ))}
                    </p>
                  )}
                </div>
              </div>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
};

const Centred = ({ children }: { children: React.ReactNode }) => (
  <div className="flex flex-1 items-center justify-center p-6 text-center text-xs text-muted-foreground">
    {children}
  </div>
);