index.js

const express = require("express");
const fs = require("fs");
const app = express();
const multer = require("multer");
const path = require("path");
const { exec } = require("child_process");

const port = process.env.PORT || 3200;

// app.set('views', path.join(__dirname, 'views'));
app.set("view engine", "ejs");
app.set("views", path.resolve("./views"));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));

app.get("/", (req, res) => {
  return res.render("index");
});

const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, "./uploads");
  },
  filename: function (req, file, cb) {
    cb(
      null,
      `${path.basename(
        file.originalname,
        path.extname(file.originalname)
      )}_${Date.now()}.pdf`
    );
  },
});

const upload = multer({ storage: storage });

const compressPDF = async (inputPaths, outputPaths) => {
  try {
    console.log("Input Paths:", await inputPaths);
    console.log("Output Paths:", await outputPaths);
    return new Promise(async (resolve, reject) => {
      for (let i = 0; i < inputPaths.length; i++) {
        // Read file
        // const filename = path.basename(outputPaths[i]);
        // const filepath = outputPaths[i];
        // const docxBuf = await fs.readFile(inputPaths[i]);
        const inputPath = inputPaths[i];
        const outputPath = outputPaths[i];
        // const quality = "/screen";
        const cmd = `gs -sDEVICE=pdfwrite \
   -dCompatibilityLevel=1.4 \
   -dNOPAUSE -dQUIET -dBATCH \
   -dColorImageDownsampleType=/Average \
   -dColorImageResolution=72 \
   -dGrayImageDownsampleType=/Average \
   -dGrayImageResolution=72 \
   -dMonoImageDownsampleType=/Average \
   -dMonoImageResolution=72 \
   -dColorImageFilter=/DCTEncode \
   -dGrayImageFilter=/DCTEncode \
   -dAutoFilterColorImages=false \
   -dAutoFilterGrayImages=false \
   -dEncodeColorImages=true \
   -dEncodeGrayImages=true \
   -dDownsampleColorImages=true \
   -dDownsampleGrayImages=true \
   -dDownsampleMonoImages=true \
   -dPDFSETTINGS=/screen \ -sOutputFile="${outputPath}" "${inputPath}"`;

        exec(cmd, (error, stdout, stderr) => {
          if (error) {
            console.error(`Compression failed: ${error.message}`);
            reject(error);
          } else {
            console.log("PDF compression successful:", outputPath);
            // resolve(outputPath);
            resolve({
              message: "File compression successfully",
              files: outputPaths,
            });
          }
        });
      }
    });
  } catch (error) {
    console.error("Error writing file:", error);
    reject({
      message: "File compression failed",
      filename,
    });
  }
};


app.post("/upload", upload.array("files"), async (req, res) => {
  console.log("Files uploaded:", await req.files);
  try {
    const files = await req.files;
    const inputPaths = [];
    const outputPaths = [];

    if (!files || files.length === 0) {
      return res.status(400).json({ message: "No files uploaded" });
    }

    for (const file of files) {
      const inputPath = path.join(__dirname, "uploads", file.filename);
      const outputPath = path.join(
        __dirname,
        "downloads",
        `${path.basename(file.filename, path.extname(file.filename))}.pdf`
      );

      inputPaths.push(inputPath);
      outputPaths.push(outputPath);
    }

    console.log("Input Paths:", inputPaths);
    console.log("Output Paths:", outputPaths);

    const response = await compressPDF(inputPaths, outputPaths);

    if (response) {
      console.log("Conversion successful:", response);
      setTimeout(() => {
        // Delete input files after conversion
        outputPaths?.forEach((outputPath) => {
          fs.unlink(outputPath, (err) => {
            if (err) {
              console.error("Error deleting input file:", err);
            } else {
              console.log("Input file deleted:", outputPath);
            }
          });
        });
      }, 120000);
      return res.status(200).json({
        message:await response.message,
        filepaths:await response.files, // return absolute paths if you use them in download
      });
    }
    else {
    return res.status(500).json({ message: "File conversion failed" });
    }
  } catch (error) {
    console.error("Upload error:", error);
    return res.status(500).json({
      message: "File conversion failed",
      error: error.message,
    });
  }
});
app.post("/download_single_file", async (req, res) => {
  try {
    console.log(req.body);
    const filepath = req.body.filepath;
    console.log("Filepath received for download:", filepath);

    if (!filepath || typeof filepath !== "string") {
      return res.status(400).json({ error: "Invalid or missing filepath" });
    }

    const absolutePath = filepath;
    const filename = filepath.split("/").pop();
    // const absolutePath = path.join(__dirname, filepath);
    // const filename = path.basename(filepath);

    res.setHeader("Content-Disposition", `attachment; filename=${filename}`);
    res.setHeader("Content-Type", "application/pdf");

    res.download(absolutePath, filename, (err) => {
      if (err) {
        console.error("Error downloading file:", err);
        res.status(500).send("Failed to download file");
      } else {
        fs.unlink(absolutePath, (err) => {
          if (err) {
            console.error("Error deleting file:", err);
          } else {
            console.log("File deleted successfully");
          }
        });
      }
    });
  } catch (error) {
    console.error(error);
    res.status(500).json({ error: "Internal server error" });
  }
});

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`);
});

module.exports = app;

// Ghost Script

// const compressPDF = (inputPath, outputPath) => {
// Command to run Ghostscript for PDF compression

// const command = `"C:\\Program Files\\gs\\gs10.02.1\\bin\\gswin64c.exe" -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -sOutputFile=${outputPath} ${inputPath}`;
// const command = `"C:\\Program Files\\gs\\gs10.02.1\\bin\\gswin64c.exe" -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=${outputPath} ${inputPath}`;
// Execute the command using exec
// exec(command, (error, stdout, stderr) => {
//     // Handle the result of the command execution
//     if (error) {
//         console.error(`Error compressing PDF: ${stderr}`);
//     } else {
//         console.log(`PDF compressed successfully: ${outputPath}`);
//     }
// });
// };