import { setButtonLabel } from "./renderers/dom.ts";
import { convertUrl, converterFormats } from "./convert/client.ts";
import { extensionOf } from "./kinds.ts";
import { readBounded } from "./source.ts";
import type { ViewerSource } from "./types.ts";

/** Bounded plain text for search/indexing consumers; the server rechecks source access. */
export async function extractText(
  source: ViewerSource,
  options: { baseURI?: string; signal?: AbortSignal; fetch?: typeof fetch } = {},
): Promise<string> {
  const url = convertUrl(source, "text", options.baseURI);
  if (!url) throw new Error("Text extraction needs a URL");
  const response = await (options.fetch ?? fetch)(url, { signal: options.signal });
  if (!response.headers.get("content-type")?.startsWith("text/plain")) {
    await response.body?.cancel();
    throw new Error("Text extraction unavailable");
  }
  return new TextDecoder().decode(await readBounded(response, 2 * 1024 * 1024));
}

export function mountExtractedText(
  parent: HTMLElement,
  source: ViewerSource,
  signal: AbortSignal,
): () => void {
  const doc = parent.ownerDocument;
  const button = doc.createElement("button");
  button.type = "button";
  button.className = "wrn-viewer-action";
  setButtonLabel(button, "Extract text");
  const details = doc.createElement("section");
  const summary = doc.createElement("h3");
  summary.textContent = "Extracted text";
  const text = doc.createElement("pre");
  details.append(summary, text);
  let disposed = false;
  void converterFormats({ baseURI: doc.baseURI })
    .then((formats) => {
      if (!disposed && source.src && formats[extensionOf(source.name)]) parent.append(button);
    })
    .catch(() => {});
  button.onclick = async () => {
    button.disabled = true;
    try {
      const result = await extractText(source, { baseURI: doc.baseURI, signal });
      if (disposed) return;
      text.textContent = result || "No text was found.";
      parent.append(details);
    } catch {
      if (!disposed) {
        text.textContent = "Text extraction is unavailable.";
        parent.append(details);
      }
    } finally {
      if (!disposed) button.disabled = false;
    }
  };
  return () => {
    disposed = true;
    button.remove();
    details.remove();
  };
}