import { useEffect, useState, useCallback, useRef } from "react";
import type { Editor as TiptapEditor } from "@tiptap/core";
import type { FrontmatterStore, FrontmatterData } from "./frontmatter/frontmatter-store";

function extractYear(dateStr?: string): number | undefined {
  if (!dateStr) return undefined;
  const d = new Date(dateStr);
  if (!Number.isNaN(d.getTime())) return d.getFullYear();
  const m = dateStr.match(/(19|20)\d{2}/);
  return m ? Number(m[0]) : undefined;
}

function buildCitationText(data: FrontmatterData): string {
  const names = data.authors.map((a) => a.name).filter(Boolean);
  const year = extractYear(data.published);
  const title = (data.title || "Untitled").replace(/\s+/g, " ").trim();
  return `${names.join(", ")}${year ? ` (${year})` : ""}. "${title}".`;
}

function buildBibtex(data: FrontmatterData): string {
  const names = data.authors.map((a) => a.name).filter(Boolean);
  const title = (data.title || "Untitled").replace(/\s+/g, " ").trim();
  const year = extractYear(data.published);
  const keyAuthor = (names[0] || "article").split(/\s+/).slice(-1)[0].toLowerCase();
  const keyTitle = title.toLowerCase().replace(/[^a-z0-9]+/g, "_").replace(/^_|_$/g, "");
  const bibKey = `${keyAuthor}${year ?? ""}_${keyTitle}`;
  const parts = [`  title={${title}}`, `  author={${names.join(" and ")}}`];
  if (year) parts.push(`  year={${year}}`);
  if (data.doi) parts.push(`  doi={${data.doi}}`);
  return `@misc{${bibKey},\n${parts.join(",\n")}\n}`;
}

interface FootnoteItem {
  index: number;
  content: string;
}

function collectFootnotes(editor: TiptapEditor): FootnoteItem[] {
  const items: FootnoteItem[] = [];
  let i = 0;
  editor.state.doc.descendants((node) => {
    if (node.type.name === "footnote") {
      i++;
      items.push({ index: i, content: (node.attrs.content as string) || "" });
    }
  });
  return items;
}

function getBibliographyHtml(editor: TiptapEditor): string {
  let html = "";
  editor.state.doc.descendants((node) => {
    if (node.type.name === "bibliography" && node.attrs.renderedHtml) {
      html = node.attrs.renderedHtml as string;
    }
  });
  return html;
}

interface EditorFooterProps {
  store: FrontmatterStore | null;
  editor: TiptapEditor | null;
}

export function EditorFooter({ store, editor }: EditorFooterProps) {
  const [data, setData] = useState<FrontmatterData | null>(null);
  const [biblioHtml, setBiblioHtml] = useState("");
  const [footnotes, setFootnotes] = useState<FootnoteItem[]>([]);

  useEffect(() => {
    if (!store) return;
    const sync = () => setData(store.getAll());
    sync();
    return store.observe(sync);
  }, [store]);

  const refreshEditorData = useCallback(() => {
    if (!editor) return;
    setBiblioHtml(getBibliographyHtml(editor));
    setFootnotes(collectFootnotes(editor));
  }, [editor]);

  const footerTimerRef = useRef(0);
  useEffect(() => {
    if (!editor) return;
    refreshEditorData();
    const debouncedRefresh = () => {
      clearTimeout(footerTimerRef.current);
      footerTimerRef.current = window.setTimeout(refreshEditorData, 500);
    };
    editor.on("update", debouncedRefresh);
    return () => {
      editor.off("update", debouncedRefresh);
      clearTimeout(footerTimerRef.current);
    };
  }, [editor, refreshEditorData]);

  if (!data) return null;

  const citation = buildCitationText(data);
  const bibtex = buildBibtex(data);

  return (
    <footer className="footer">
      <div className="footer-inner">
        <section className="citation-block">
          <p className="footer-heading" role="heading" aria-level={2}>Citation</p>
          <p>For attribution in academic contexts, please cite this work as</p>
          <pre className="citation short">{citation}</pre>
          <p>BibTeX citation</p>
          <pre className="citation long">{bibtex}</pre>
        </section>

        {data.doi && (
          <section className="doi-block">
            <p className="footer-heading" role="heading" aria-level={2}>DOI</p>
            <p>
              <a href={`https://doi.org/${data.doi}`} target="_blank" rel="noopener noreferrer">
                {data.doi}
              </a>
            </p>
          </section>
        )}

        {data.licence && (
          <section className="reuse-block">
            <p className="footer-heading" role="heading" aria-level={2}>Reuse</p>
            <p dangerouslySetInnerHTML={{ __html: data.licence }} />
          </section>
        )}

        {biblioHtml && (
          <section className="references-block">
            <p className="footer-heading" role="heading" aria-level={2}>References</p>
            <div
              className="bibliography-content"
              dangerouslySetInnerHTML={{ __html: biblioHtml }}
            />
          </section>
        )}

        {footnotes.length > 0 && (
          <section className="references-block">
            <p className="footer-heading" role="heading" aria-level={2}>Footnotes</p>
            <ol className="footnotes-list">
              {footnotes.map((fn) => (
                <li key={fn.index} id={`fn-${fn.index}`}>
                  <p>{fn.content || "Empty footnote"}</p>
                </li>
              ))}
            </ol>
          </section>
        )}

        <div className="template-credit">
          <p>
            Made with ❤️ with{" "}
            <a href="https://huggingface.co/spaces/tfrere/research-article-template-editor" target="_blank" rel="noopener noreferrer">
              research article template editor
            </a>
          </p>
        </div>
      </div>
    </footer>
  );
}