From 9fbc61a04d3d55f12d74e2c3a30abdd65169973a Mon Sep 17 00:00:00 2001
From: David Nguyen <davidngu28@gmail.com>
Date: Tue, 11 Jun 2024 19:04:55 +1000
Subject: [PATCH] fix: insert fields correctly for rotated pdfs

---
 .../server-only/pdf/insert-field-in-pdf.ts    | 85 ++++++++++++++++++-
 1 file changed, 81 insertions(+), 4 deletions(-)

diff --git a/packages/lib/server-only/pdf/insert-field-in-pdf.ts b/packages/lib/server-only/pdf/insert-field-in-pdf.ts
index 8ff575d65..7b37c367f 100644
--- a/packages/lib/server-only/pdf/insert-field-in-pdf.ts
+++ b/packages/lib/server-only/pdf/insert-field-in-pdf.ts
@@ -1,6 +1,7 @@
 // https://github.com/Hopding/pdf-lib/issues/20#issuecomment-412852821
 import fontkit from '@pdf-lib/fontkit';
-import { PDFDocument } from 'pdf-lib';
+import { PDFDocument, RotationTypes, degrees, radiansToDegrees } from 'pdf-lib';
+import { match } from 'ts-pattern';
 
 import {
   DEFAULT_HANDWRITING_FONT_SIZE,
@@ -37,7 +38,25 @@ export const insertFieldInPDF = async (pdf: PDFDocument, field: FieldWithSignatu
     throw new Error(`Page ${field.page} does not exist`);
   }
 
-  const { width: pageWidth, height: pageHeight } = page.getSize();
+  const pageRotation = page.getRotation();
+
+  let pageRotationInDegrees = match(pageRotation.type)
+    .with(RotationTypes.Degrees, () => pageRotation.angle)
+    .with(RotationTypes.Radians, () => radiansToDegrees(pageRotation.angle))
+    .exhaustive();
+
+  // Round to the closest multiple of 90 degrees.
+  pageRotationInDegrees = Math.round(pageRotationInDegrees / 90) * 90;
+
+  const isPageRotatedToLandscape = pageRotationInDegrees === 90 || pageRotationInDegrees === 270;
+
+  let { width: pageWidth, height: pageHeight } = page.getSize();
+
+  // For landscape pages, swap the width and height so we can calculate item position the same way
+  // the user placed it in the editor.
+  if (isPageRotatedToLandscape) {
+    [pageWidth, pageHeight] = [pageHeight, pageWidth];
+  }
 
   const fieldWidth = pageWidth * (Number(field.width) / 100);
   const fieldHeight = pageHeight * (Number(field.height) / 100);
@@ -65,17 +84,31 @@ export const insertFieldInPDF = async (pdf: PDFDocument, field: FieldWithSignatu
     imageWidth = imageWidth * scalingFactor;
     imageHeight = imageHeight * scalingFactor;
 
-    const imageX = fieldX + (fieldWidth - imageWidth) / 2;
+    let 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;
 
+    if (pageRotationInDegrees !== 0) {
+      const adjustedPosition = adjustPositionForRotation(
+        pageWidth,
+        pageHeight,
+        imageX,
+        imageY,
+        pageRotationInDegrees,
+      );
+
+      imageX = adjustedPosition.xPos;
+      imageY = adjustedPosition.yPos;
+    }
+
     page.drawImage(image, {
       x: imageX,
       y: imageY,
       width: imageWidth,
       height: imageHeight,
+      rotate: degrees(pageRotationInDegrees),
     });
   } else {
     const longestLineInTextForWidth = field.customText
@@ -90,17 +123,31 @@ export const insertFieldInPDF = async (pdf: PDFDocument, field: FieldWithSignatu
     fontSize = Math.max(Math.min(fontSize * scalingFactor, maxFontSize), minFontSize);
     textWidth = font.widthOfTextAtSize(longestLineInTextForWidth, fontSize);
 
-    const textX = fieldX + (fieldWidth - textWidth) / 2;
+    let textX = fieldX + (fieldWidth - textWidth) / 2;
     let textY = fieldY + (fieldHeight - textHeight) / 2;
 
     // Invert the Y axis since PDFs use a bottom-left coordinate system
     textY = pageHeight - textY - textHeight;
 
+    if (pageRotationInDegrees !== 0) {
+      const adjustedPosition = adjustPositionForRotation(
+        pageWidth,
+        pageHeight,
+        textX,
+        textY,
+        pageRotationInDegrees,
+      );
+
+      textX = adjustedPosition.xPos;
+      textY = adjustedPosition.yPos;
+    }
+
     page.drawText(field.customText, {
       x: textX,
       y: textY,
       size: fontSize,
       font,
+      rotate: degrees(pageRotationInDegrees),
     });
   }
 
@@ -117,3 +164,33 @@ export const insertFieldInPDFBytes = async (
 
   return await pdfDoc.save();
 };
+
+const adjustPositionForRotation = (
+  pageWidth: number,
+  pageHeight: number,
+  xPos: number,
+  yPos: number,
+  pageRotationInDegrees: number,
+) => {
+  if (pageRotationInDegrees === 270) {
+    xPos = pageWidth - xPos;
+
+    [xPos, yPos] = [yPos, xPos];
+  }
+
+  if (pageRotationInDegrees === 90) {
+    yPos = pageHeight - yPos;
+
+    [xPos, yPos] = [yPos, xPos];
+  }
+
+  if (pageRotationInDegrees === 180) {
+    xPos = pageWidth - xPos;
+    yPos = pageHeight - yPos;
+  }
+
+  return {
+    xPos,
+    yPos,
+  };
+};