import { useCallback, useEffect, useRef, useState } from 'react';
import type { SplitResult } from '../pdf/pdfTypes';

export interface PdfDownload {
  id: string;
  filename: string;
  url: string;
}

export interface SplitPdfDownload extends PdfDownload {
  pageIndex: number;
}

export interface PdfBlobResult {
  blob: Blob;
  filename: string;
}

function revokeDownload(download: PdfDownload | null): void {
  if (download) {
    URL.revokeObjectURL(download.url);
  }
}

function revokeDownloads(downloads: PdfDownload[]): void {
  downloads.forEach(revokeDownload);
}

function createDownload(id: string, filename: string, blob: Blob): PdfDownload {
  return {
    id,
    filename,
    url: URL.createObjectURL(blob),
  };
}

export function usePdfGeneratedOutputs() {
  const [splitDownloads, setSplitDownloads] = useState<SplitPdfDownload[]>([]);
  const [subsetDownload, setSubsetDownload] = useState<PdfDownload | null>(
    null
  );
  const [exportDownload, setExportDownload] = useState<PdfDownload | null>(
    null
  );
  const [splitZipDownload, setSplitZipDownload] = useState<PdfDownload | null>(
    null
  );

  const splitDownloadsRef = useRef<SplitPdfDownload[]>([]);
  const subsetDownloadRef = useRef<PdfDownload | null>(null);
  const exportDownloadRef = useRef<PdfDownload | null>(null);
  const splitZipDownloadRef = useRef<PdfDownload | null>(null);

  const replaceSplitResults = useCallback(
    (results: SplitResult[], zipResult?: PdfBlobResult) => {
      const nextDownloads: SplitPdfDownload[] = results.map((result) => ({
        ...createDownload(
          `split-${result.pageIndex}-${result.filename}`,
          result.filename,
          result.blob
        ),
        pageIndex: result.pageIndex,
      }));

      const nextZipDownload = zipResult
        ? createDownload('split-zip', zipResult.filename, zipResult.blob)
        : null;

      revokeDownloads(splitDownloadsRef.current);
      revokeDownload(splitZipDownloadRef.current);

      splitDownloadsRef.current = nextDownloads;
      splitZipDownloadRef.current = nextZipDownload;

      setSplitDownloads(nextDownloads);
      setSplitZipDownload(nextZipDownload);
    },
    []
  );

  const clearSplitResults = useCallback(() => {
    revokeDownloads(splitDownloadsRef.current);
    revokeDownload(splitZipDownloadRef.current);

    splitDownloadsRef.current = [];
    splitZipDownloadRef.current = null;

    setSplitDownloads([]);
    setSplitZipDownload(null);
  }, []);

  const replaceSubsetResult = useCallback((blob: Blob, filename: string) => {
    const nextDownload = createDownload('subset', filename, blob);

    revokeDownload(subsetDownloadRef.current);
    subsetDownloadRef.current = nextDownload;
    setSubsetDownload(nextDownload);
  }, []);

  const clearSubsetResult = useCallback(() => {
    revokeDownload(subsetDownloadRef.current);
    subsetDownloadRef.current = null;
    setSubsetDownload(null);
  }, []);

  const replaceExportResult = useCallback((blob: Blob, filename: string) => {
    const nextDownload = createDownload('export', filename, blob);

    revokeDownload(exportDownloadRef.current);
    exportDownloadRef.current = nextDownload;
    setExportDownload(nextDownload);
  }, []);

  const clearExportResult = useCallback(() => {
    revokeDownload(exportDownloadRef.current);
    exportDownloadRef.current = null;
    setExportDownload(null);
  }, []);

  const clearAllResults = useCallback(() => {
    revokeDownloads(splitDownloadsRef.current);
    revokeDownload(subsetDownloadRef.current);
    revokeDownload(exportDownloadRef.current);
    revokeDownload(splitZipDownloadRef.current);

    splitDownloadsRef.current = [];
    subsetDownloadRef.current = null;
    exportDownloadRef.current = null;
    splitZipDownloadRef.current = null;

    setSplitDownloads([]);
    setSubsetDownload(null);
    setExportDownload(null);
    setSplitZipDownload(null);
  }, []);

  useEffect(() => {
    return () => {
      revokeDownloads(splitDownloadsRef.current);
      revokeDownload(subsetDownloadRef.current);
      revokeDownload(exportDownloadRef.current);
      revokeDownload(splitZipDownloadRef.current);
    };
  }, []);

  return {
    splitDownloads,
    subsetDownload,
    exportDownload,
    splitZipDownload,
    replaceSplitResults,
    clearSplitResults,
    replaceSubsetResult,
    clearSubsetResult,
    replaceExportResult,
    clearExportResult,
    clearAllResults,
  };
}