Embedding Objects in PDF using Google Apps Script

/**
 * ### Description
 * This is a Class object for embedding objects into PDF using Google Apps Script.
 *
 * Author: Tanaike ( https://tanaikech.github.io/ )
 */
class EmbedObjects {
  /**
   * ### Description
   * Constructor of this class.
   *
   * @return {void}
   */
  constructor() {
    this.cdnjs = "https://cdn.jsdelivr.net/npm/pdf-lib/dist/pdf-lib.min.js"; // or "https://cdnjs.cloudflare.com/ajax/libs/pdf-lib/1.17.1/pdf-lib.min.js"
    this.cdnFontkit =
      "https://unpkg.com/@pdf-lib/fontkit/dist/fontkit.umd.min.js";
    this.loadPdfLib_();
  }

  /**
   * ### Description
   * Embed objects into PDF using pdf-lib.
   *
   * @param {String} id File ID of PDF file. And, when you give the file ID of Google Docs files (Document, Spreadsheet, Slide), those are automatically converted to PDF data. You can also use it.
   * @param {Object} object Objects for embedding.
   * @return {Object} Blob of PDF including the updated PDF.
   */
  run(id, object) {
    if (!id || id == "") {
      throw new Error(
        "Please set the file ID of PDF file. And, when you give the file ID of Google Docs files (Document, Spreadsheet, Slide), those are automatically converted to PDF data. You can also use it."
      );
    }
    if (!object || typeof object != "object") {
      throw new Error("Please an object for embeddig the objects.");
    }
    return new Promise(async (resolve, reject) => {
      try {
        const { updatedObject, customFontCheck } = this.updateObject_(object);
        const blob = DriveApp.getFileById(id).getBlob();
        const pdfData = await this.PDFLib.PDFDocument.load(
          new Uint8Array(blob.getBytes())
        );
        const numberOfPages = pdfData.getPageCount();
        const pdfDoc = await this.PDFLib.PDFDocument.create();
        if (customFontCheck) {
          this.loadFontkit_();
          pdfDoc.registerFontkit(this.fontkit);
        }
        const pages = await pdfDoc.copyPages(
          pdfData,
          [...Array(numberOfPages)].map((_, i) => i)
        );
        for (let i = 0; i < pages.length; i++) {
          const page = pages[i];
          const forPage = updatedObject[`page${i + 1}`];
          if (forPage) {
            for (let j = 0; j < forPage.length; j++) {
              const o = forPage[j];
              if (o.imageFileId) {
                const image = await pdfDoc[o.method](o.imageBytes);
                if (o.scale) {
                  const updatedImage = image.scale(o.scale);
                  o.width = o.width || updatedImage.width;
                  o.height = o.height || updatedImage.height;
                } else {
                  o.width = o.width || image.width;
                  o.height = o.height || image.height;
                }
                delete o.imageBytes;
                delete o.method;
                delete o.imageFileId;
                delete o.scale;
                page.drawImage(image, o);
              } else if (o.text) {
                if (o.standardFont || o.customFont) {
                  o.font = await pdfDoc.embedFont(
                    o.standardFont
                      ? this.PDFLib.StandardFonts[o.standardFont]
                      : o.customFont
                  );
                }
                page.drawText(o.text, o);
              }
            }
          }
          pdfDoc.addPage(page);
        }
        const bytes = await pdfDoc.save();
        const newBlob = Utilities.newBlob(
          [...new Int8Array(bytes)],
          MimeType.PDF,
          `new_${blob.getName()}`
        );
        resolve(newBlob);
      } catch (e) {
        reject(e);
      }
    });
  }

  /**
   * ### Description
   * Load pdf-lib. https://pdf-lib.js.org/docs/api/classes/pdfdocument
   *
   * @return {void}
   */
  loadPdfLib_() {
    eval(
      UrlFetchApp.fetch(this.cdnjs)
        .getContentText()
        .replace(
          /setTimeout\(.*?,.*?(\d*?)\)/g,
          "Utilities.sleep($1);return t();"
        )
    );
  }

  /**
   * ### Description
   * Load fontkit. https://github.com/Hopding/fontkit
   *
   * @return {void}
   */
  loadFontkit_() {
    eval(UrlFetchApp.fetch(this.cdnFontkit).getContentText());
  }

  /**
   * ### Description
   * Update object.
   *
   * @param {Object} object Object for embedding objects into PDF.
   * @return {void}
   */
  updateObject_(object) {
    let customFontCheck = false;
    const updatedObject = Object.fromEntries(
      Object.entries(object).map(([k, p]) => [
        k,
        p.map((e) => {
          if (e.imageFileId) {
            const imageBlob = DriveApp.getFileById(e.imageFileId).getBlob();
            const imageBytes = new Uint8Array(imageBlob.getBytes());
            const mimeType = imageBlob.getContentType();
            let method;
            if (mimeType == MimeType.PNG) {
              method = "embedPng";
            } else if (mimeType == MimeType.JPEG) {
              method = "embedJpg";
            } else {
              throw new Error("This image file cannot be used.");
            }
            e.method = method;
            e.imageBytes = imageBytes;
          } else if (e.text) {
            if (e.customFont) {
              customFontCheck = true;
              e.customFont = new Uint8Array(e.customFont.getBytes());
            }
          }
          return e;
        }),
      ])
    );
    return { updatedObject, customFontCheck };
  }
}

function sample() {
  const pdfFileId = "### file ID of PDF file ###"; // Or, when you use the file ID of Google Docs files (Document, Spreadsheet, Slide), those files are automatically converted to the PDF format.
  const object = {
    page1: [
      {
        text: "sample text1",
        x: 150,
        y: 635,
        standardFont: "Helvetica",
        size: 30,
      },
      {
        text: "sample text2",
        x: 390,
        y: 602,
        standardFont: "TimesRoman",
        size: 16,
      },
      {
        imageFileId: "### file ID of image file ###",
        x: 175,
        y: 340,
        scale: 0.35,
      },
    ],
  };
  const folderId = "### folder ID ###"; // New PDF is created in this folder.
  const EO = new EmbedObjects();
  EO.run(pdfFileId, object)
    .then((res) => DriveApp.getFolderById(folderId).createFile(res))
    .catch((err) => console.log(err));
}