// Shared PDF download logic used by the markdown and textResponse
// plugin views. Encapsulates the POST /api/pdf/markdown call, the
// in-flight `pdfDownloading` flag, the `pdfError` state, and the
// blob-to-download dance (createObjectURL → click → revoke).
//
// Error handling contract: any failure path (network, non-OK HTTP,
// malformed blob) sets pdfDownloading back to false and populates
// pdfError with a user-facing message. Callers can render pdfError
// below the download button.

import { ref, type Ref } from "vue";
import { API_ROUTES } from "../config/apiRoutes";
import { postMarkdownForBlob, type MarkdownRenderOptions } from "../utils/markdownBlobRequest";
import { errorMessage } from "../utils/errors";

export interface UsePdfDownloadHandle {
  pdfDownloading: Ref<boolean>;
  pdfError: Ref<string | null>;
  downloadPdf: (markdown: string, filename: string, options?: MarkdownRenderOptions) => Promise<void>;
}

export function usePdfDownload(): UsePdfDownloadHandle {
  const pdfDownloading = ref(false);
  const pdfError = ref<string | null>(null);

  async function downloadPdf(markdown: string, filename: string, options: MarkdownRenderOptions = {}): Promise<void> {
    pdfError.value = null;
    pdfDownloading.value = true;
    let url: string | null = null;
    try {
      const response = await postMarkdownForBlob(API_ROUTES.pdf.markdown, markdown, filename, options);
      if (!response.ok) {
        const errText = await response.text().catch(() => "");
        pdfError.value = `PDF error ${response.status}: ${errText}`;
        return;
      }
      const blob = await response.blob();
      url = URL.createObjectURL(blob);
      const anchor = document.createElement("a");
      anchor.href = url;
      anchor.download = filename;
      anchor.click();
    } catch (err) {
      pdfError.value = errorMessage(err);
    } finally {
      // Always clean up the object URL and release the in-flight flag
      // so the button is never left disabled forever.
      if (url) URL.revokeObjectURL(url);
      pdfDownloading.value = false;
    }
  }

  return { pdfDownloading, pdfError, downloadPdf };
}