bentopdf/src/js/logic/pdf-to-tiff-page.ts

import { showLoader, hideLoader, showAlert } from '../ui.js';
import {
  downloadFile,
  formatBytes,
  readFileAsArrayBuffer,
  getPDFDocument,
  getCleanPdfFilename,
} from '../utils/helpers.js';
import { createIcons, icons } from 'lucide';
import JSZip from 'jszip';
import * as pdfjsLib from 'pdfjs-dist';
import UTIF from 'utif';
import { PDFPageProxy } from 'pdfjs-dist';

pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(
  'pdfjs-dist/build/pdf.worker.min.mjs',
  import.meta.url
).toString();

let files: File[] = [];

const updateUI = () => {
  const fileDisplayArea = document.getElementById('file-display-area');
  const optionsPanel = document.getElementById('options-panel');
  const dropZone = document.getElementById('drop-zone');

  if (!fileDisplayArea || !optionsPanel || !dropZone) return;

  fileDisplayArea.innerHTML = '';

  if (files.length > 0) {
    optionsPanel.classList.remove('hidden');

    files.forEach((file) => {
      const fileDiv = document.createElement('div');
      fileDiv.className =
        'flex items-center justify-between bg-gray-700 p-3 rounded-lg text-sm';

      const infoContainer = document.createElement('div');
      infoContainer.className = 'flex flex-col overflow-hidden';

      const nameSpan = document.createElement('div');
      nameSpan.className = 'truncate font-medium text-gray-200 text-sm mb-1';
      nameSpan.textContent = file.name;

      const metaSpan = document.createElement('div');
      metaSpan.className = 'text-xs text-gray-400';
      metaSpan.textContent = `${formatBytes(file.size)} • Loading pages...`; // Initial state

      infoContainer.append(nameSpan, metaSpan);

      const removeBtn = document.createElement('button');
      removeBtn.className =
        'ml-4 text-red-400 hover:text-red-300 flex-shrink-0';
      removeBtn.innerHTML = '<i data-lucide="trash-2" class="w-4 h-4"></i>';
      removeBtn.onclick = () => {
        files = [];
        updateUI();
      };

      fileDiv.append(infoContainer, removeBtn);
      fileDisplayArea.appendChild(fileDiv);

      // Fetch page count asynchronously
      readFileAsArrayBuffer(file)
        .then((buffer) => {
          return getPDFDocument(buffer).promise;
        })
        .then((pdf) => {
          metaSpan.textContent = `${formatBytes(file.size)} • ${pdf.numPages} page${pdf.numPages !== 1 ? 's' : ''}`;
        })
        .catch((e) => {
          console.warn('Error loading PDF page count:', e);
          metaSpan.textContent = formatBytes(file.size);
        });
    });

    // Initialize icons immediately after synchronous render
    createIcons({ icons });
  } else {
    optionsPanel.classList.add('hidden');
  }
};

const resetState = () => {
  files = [];
  const fileInput = document.getElementById('file-input') as HTMLInputElement;
  if (fileInput) fileInput.value = '';
  updateUI();
};

async function convert() {
  if (files.length === 0) {
    showAlert('No File', 'Please upload a PDF file first.');
    return;
  }
  showLoader('Converting to TIFF...');
  try {
    const pdf = await getPDFDocument(await readFileAsArrayBuffer(files[0]))
      .promise;

    if (pdf.numPages === 1) {
      const page = await pdf.getPage(1);
      const blob = await renderPage(page, 1);
      downloadFile(
        blob.blobData,
        getCleanPdfFilename(files[0].name) + '.' + blob.ending
      );
    } else {
      const zip = new JSZip();
      for (let i = 1; i <= pdf.numPages; i++) {
        const page = await pdf.getPage(i);
        const blob = await renderPage(page, i);
        if (blob.blobData) {
          zip.file(`page_${i}.` + blob.ending, blob.blobData);
        }
      }

      const zipBlob = await zip.generateAsync({ type: 'blob' });
      downloadFile(zipBlob, getCleanPdfFilename(files[0].name) + '_tiffs.zip');
    }

    showAlert(
      'Success',
      'PDF converted to TIFFs successfully!',
      'success',
      () => {
        resetState();
      }
    );
  } catch (e) {
    console.error(e);
    showAlert(
      'Error',
      'Failed to convert PDF to TIFF. The file might be corrupted.'
    );
  } finally {
    hideLoader();
  }
}

async function renderPage(
  page: PDFPageProxy,
  pageNumber: number
): Promise<{ blobData: Blob | null; ending: string }> {
  const viewport = page.getViewport({ scale: 2.0 });
  const canvas = document.createElement('canvas');
  const context = canvas.getContext('2d');
  canvas.height = viewport.height;
  canvas.width = viewport.width;

  await page.render({
    canvasContext: context!,
    viewport: viewport,
    canvas,
  }).promise;

  const imageData = context!.getImageData(0, 0, canvas.width, canvas.height);
  const rgba = imageData.data;

  try {
    const tiffData = UTIF.encodeImage(
      new Uint8Array(rgba),
      canvas.width,
      canvas.height
    );
    const tiffBlob = new Blob([tiffData], { type: 'image/tiff' });
    return {
      blobData: tiffBlob,
      ending: 'tiff',
    };
  } catch (encodeError: any) {
    console.warn(
      `TIFF encoding failed for page ${pageNumber}, using PNG fallback:`,
      encodeError
    );
    // Fallback to PNG if TIFF encoding fails (e.g., PackBits compression issues)
    const pngBlob = await new Promise<Blob | null>((resolve) =>
      canvas.toBlob(resolve, 'image/png')
    );
    if (pngBlob) {
      return {
        blobData: pngBlob,
        ending: 'png',
      };
    }
  }

  return {
    blobData: null,
    ending: 'tiff',
  };
}

document.addEventListener('DOMContentLoaded', () => {
  const fileInput = document.getElementById('file-input') as HTMLInputElement;
  const dropZone = document.getElementById('drop-zone');
  const processBtn = document.getElementById('process-btn');
  const backBtn = document.getElementById('back-to-tools');

  if (backBtn) {
    backBtn.addEventListener('click', () => {
      window.location.href = import.meta.env.BASE_URL;
    });
  }

  const handleFileSelect = (newFiles: FileList | null) => {
    if (!newFiles || newFiles.length === 0) return;
    const validFiles = Array.from(newFiles).filter(
      (file) => file.type === 'application/pdf'
    );

    if (validFiles.length === 0) {
      showAlert('Invalid File', 'Please upload a PDF file.');
      return;
    }

    files = [validFiles[0]];
    updateUI();
  };

  if (fileInput && dropZone) {
    fileInput.addEventListener('change', (e) => {
      handleFileSelect((e.target as HTMLInputElement).files);
    });

    dropZone.addEventListener('dragover', (e) => {
      e.preventDefault();
      dropZone.classList.add('bg-gray-700');
    });

    dropZone.addEventListener('dragleave', (e) => {
      e.preventDefault();
      dropZone.classList.remove('bg-gray-700');
    });

    dropZone.addEventListener('drop', (e) => {
      e.preventDefault();
      dropZone.classList.remove('bg-gray-700');
      handleFileSelect(e.dataTransfer?.files ?? null);
    });

    fileInput.addEventListener('click', () => {
      fileInput.value = '';
    });
  }

  if (processBtn) {
    processBtn.addEventListener('click', convert);
  }
});