import { useMutation, useQueries, useQuery, useQueryClient } from "@tanstack/react-query";
import { useState, type ReactNode } from "react";
import { useLocation } from "wouter";
import { api, type EntryView, type Work } from "../api.ts";
import { friendlyError, mediaTypeLabel } from "../format.ts";
import { useDebounced } from "../hooks.ts";
import { Cover } from "./Cover.tsx";
import { Icon } from "./Icon.tsx";

/** Drafts only: suggested matches and a catalogue search. Linking keeps the user's rating, reads and review. */
export function LinkToCatalogue({ entry }: { entry: EntryView }) {
  const qc = useQueryClient();
  const [, navigate] = useLocation();
  const [q, setQ] = useState("");
  const term = useDebounced(q.trim());
  const suggestions = useQuery({ queryKey: ["suggestions", entry.workId], queryFn: () => api.suggestions(entry.workId) });
  const candidates = useQueries({
    queries: (suggestions.data ?? []).slice(0, 5).map((s) => ({ queryKey: ["work", s.candidateWorkId], queryFn: () => api.work(s.candidateWorkId), staleTime: 300_000 })),
  });
  const search = useQuery({
    queryKey: ["works-search", term],
    queryFn: () => api.searchWorks(term),
    enabled: term.length >= 2,
  });

  const done = (newId?: string) => {
    void qc.invalidateQueries({ queryKey: ["entries"] });
    void qc.invalidateQueries({ queryKey: ["entry", entry.id] });
    void qc.invalidateQueries({ queryKey: ["suggestions", entry.workId] });
    if (newId && newId !== entry.id) navigate(`/entries/${newId}`, { replace: true });
  };
  const move = useMutation({ mutationFn: (workId: string) => api.moveEntry(entry.id, workId), onSuccess: (e) => done(e.id) });
  const accept = useMutation({ mutationFn: api.acceptSuggestion, onSuccess: () => done() });
  const reject = useMutation({ mutationFn: api.rejectSuggestion, onSuccess: () => done() });
  const busy = move.isPending || accept.isPending || reject.isPending;
  const error = move.error ?? accept.error ?? reject.error;

  const row = (w: Work, actions: ReactNode) => (
    <li key={w.id}>
      <Cover url={w.cover_url} mediaType={w.media_type} draft={false} size="small" />
      <div style={{ minWidth: 0 }}>
        <div>{w.title}</div>
        <div className="m">{[mediaTypeLabel(w.media_type), w.year, w.creators?.[0]?.name].filter(Boolean).join(" · ")}</div>
      </div>
      <div className="acts">{actions}</div>
    </li>
  );

  const results = (search.data ?? []).filter((w) => w.id !== entry.workId);
  return (
    <section className="box link-box" aria-labelledby="link-title">
      <div className="box-head">
        <h2 id="link-title"><Icon name="link" /> Link to catalogue</h2>
      </div>
      <p>This is a draft. Link it to a catalogue entry to fill in the cover and details. Your rating, reads and review stay as they are.</p>

      {candidates.length > 0 && (
        <>
          <h3 className="sub">Suggested</h3>
          <ul className="results">
            {suggestions.data!.slice(0, 5).map((s, i) => {
              const w = candidates[i]?.data;
              if (!w) return null;
              return row(
                w,
                <>
                  <button type="button" className="btn primary small" disabled={busy} onClick={() => accept.mutate(s.id)}>Link</button>
                  <button type="button" className="btn ghost small" disabled={busy} onClick={() => reject.mutate(s.id)}>Not this</button>
                </>,
              );
            })}
          </ul>
        </>
      )}

      <div className="search">
        <Icon name="search" />
        <label htmlFor="catalogue-search" className="sr-only">Search the catalogue</label>
        <input
          id="catalogue-search"
          className="input"
          type="search"
          placeholder="Search the catalogue…"
          value={q}
          onChange={(e) => setQ(e.target.value)}
        />
      </div>
      {term.length >= 2 && !search.isPending && (
        results.length === 0 ? (
          <p className="hint">Nothing in the catalogue matches “{term}”. Connect a source to bring in more.</p>
        ) : (
          <ul className="results" aria-label="Search results">
            {results.map((w) =>
              row(w, <button type="button" className="btn primary small" disabled={busy} onClick={() => move.mutate(w.id)}>Link</button>),
            )}
          </ul>
        )
      )}
      {error && <p className="error-text" role="alert">{friendlyError(error)}</p>}
    </section>
  );
}