feat: document authoring

packages/lib/server-only/pdf/insert-field-in-pdf.ts

@@ -0,0 +1,144 @@
+import fontkit from '@pdf-lib/fontkit';
+import { readFileSync } from 'fs';
+import { PDFDocument, StandardFonts } from 'pdf-lib';
+
+import { FieldType } from '@documenso/prisma/client';
+import { isSignatureFieldType } from '@documenso/prisma/guards/is-signature-field';
+import { FieldWithSignature } from '@documenso/prisma/types/field-with-signature';
+
+const DEFAULT_STANDARD_FONT_SIZE = 15;
+const DEFAULT_HANDWRITING_FONT_SIZE = 50;
+
+export const insertFieldInPDF = async (pdf: PDFDocument, field: FieldWithSignature) => {
+  const isSignatureField = isSignatureFieldType(field.type);
+
+  pdf.registerFontkit(fontkit);
+
+  const fontCaveat = readFileSync('./public/fonts/caveat.ttf');
+
+  const pages = pdf.getPages();
+
+  const maxFontSize = isSignatureField ? DEFAULT_HANDWRITING_FONT_SIZE : DEFAULT_STANDARD_FONT_SIZE;
+  let fontSize = isSignatureField ? DEFAULT_HANDWRITING_FONT_SIZE : DEFAULT_STANDARD_FONT_SIZE;
+
+  const page = pages.at(field.page - 1);
+
+  if (!page) {
+    throw new Error(`Page ${field.page} does not exist`);
+  }
+
+  const { width: pageWidth, height: pageHeight } = page.getSize();
+
+  const fieldWidth = pageWidth * (Number(field.width) / 100);
+  const fieldHeight = pageHeight * (Number(field.height) / 100);
+
+  const fieldX = pageWidth * (Number(field.positionX) / 100);
+  const fieldY = pageHeight * (Number(field.positionY) / 100);
+
+  console.log({
+    fieldWidth,
+    fieldHeight,
+    fieldX,
+    fieldY,
+    pageWidth,
+    pageHeight,
+  });
+
+  const font = await pdf.embedFont(isSignatureField ? fontCaveat : StandardFonts.Helvetica);
+
+  if (field.type === FieldType.SIGNATURE || field.type === FieldType.FREE_SIGNATURE) {
+    await pdf.embedFont(fontCaveat);
+  }
+
+  const isInsertingImage =
+    isSignatureField && typeof field.Signature?.signatureImageAsBase64 === 'string';
+
+  if (isSignatureField && isInsertingImage) {
+    const image = await pdf.embedPng(field.Signature?.signatureImageAsBase64 ?? '');
+
+    let imageWidth = image.width;
+    let imageHeight = image.height;
+
+    const initialDimensions = {
+      width: imageWidth,
+      height: imageHeight,
+    };
+
+    const scalingFactor = Math.min(fieldWidth / imageWidth, fieldHeight / imageHeight, 1);
+
+    imageWidth = imageWidth * scalingFactor;
+    imageHeight = imageHeight * scalingFactor;
+
+    const imageX = fieldX + (fieldWidth - imageWidth) / 2;
+    let imageY = fieldY + (fieldHeight - imageHeight) / 2;
+
+    // Invert the Y axis since PDFs use a bottom-left coordinate system
+    imageY = pageHeight - imageY - imageHeight;
+
+    console.log({
+      initialDimensions,
+      scalingFactor,
+      imageWidth,
+      imageHeight,
+      imageX,
+      imageY,
+    });
+
+    page.drawImage(image, {
+      x: imageX,
+      y: imageY,
+      width: imageWidth,
+      height: imageHeight,
+    });
+  } else {
+    let textWidth = font.widthOfTextAtSize(field.customText, fontSize);
+    const textHeight = font.heightAtSize(fontSize);
+
+    const initialDimensions = {
+      width: textWidth,
+      height: textHeight,
+    };
+
+    const scalingFactor = Math.min(fieldWidth / textWidth, fieldHeight / textHeight, 1);
+
+    fontSize = Math.max(fontSize * scalingFactor, maxFontSize);
+    textWidth = font.widthOfTextAtSize(field.customText, fontSize);
+
+    const textX = fieldX + (fieldWidth - textWidth) / 2;
+    let textY = fieldY + (fieldHeight - textHeight) / 2;
+
+    console.log({
+      initialDimensions,
+      scalingFactor,
+      textWidth,
+      textHeight,
+      textX,
+      textY,
+      pageWidth,
+      pageHeight,
+    });
+
+    // Invert the Y axis since PDFs use a bottom-left coordinate system
+    textY = pageHeight - textY - textHeight;
+
+    page.drawText(field.customText, {
+      x: textX,
+      y: textY,
+      size: fontSize,
+      font,
+    });
+  }
+
+  return pdf;
+};
+
+export const insertFieldInPDFBytes = async (
+  pdf: ArrayBuffer | Uint8Array | string,
+  field: FieldWithSignature,
+) => {
+  const pdfDoc = await PDFDocument.load(pdf);
+
+  await insertFieldInPDF(pdfDoc, field);
+
+  return await pdfDoc.save();
+};