PDF -> PNG Convertor

* DockerFile Addditions
+ Helper Functions

src/Controllers/Convert.ts

@@ -0,0 +1,86 @@
+import { Request, Response, NextFunction, Router } from 'express';
+import { Magic, MAGIC_MIME_TYPE } from 'mmmagic';
+import { findFile, returnError } from '../Helpers/ApiHelper';
+import { convertFileToPNG } from '../Models/ConversionModel';
+
+const magic = new Magic(MAGIC_MIME_TYPE);
+
+const convertController = async (req: Request, res: Response, next: NextFunction) => {
+
+    // Check if any files were sent over.
+    if ( !req.files || req.files?.length <= 0 ) {
+        return returnError(res, {
+            "message": "No files have been provided, this api endpoint requres files to be able to process them",
+            "error":   "Empty files array"
+        })
+    }
+
+    // Get our file
+    const inputFile = findFile('inputFile', req.files as Express.Multer.File[]);
+
+    // Check if we have an input File
+    if ( inputFile == null ) {
+        return returnError(res, {
+            "message": "Broken file name in request, please try again.",
+            "error":   "Files are in the call, but we require the name inputFile to be sent over."
+        })
+    }
+
+    let inputFileType: string | null = null;
+
+    // Get the input file format
+    await new Promise<string | string[]>((_r, _e) => { 
+        magic.detectFile(inputFile.path, (err, fileType) => {
+            if ( err ) {
+                return _e(err);
+            } else {
+                return _r(fileType);
+            }
+        })
+    })
+    .then( ftype => {
+        console.log(ftype);
+
+        if ( typeof ftype != 'object' ) {
+            inputFileType = ftype;
+        } else {
+            inputFileType = ftype[0];
+        }
+
+    })
+    .catch( err => {
+        console.error(err);
+    })
+
+    if ( !!!inputFileType ) {
+        return returnError(res, {
+            message: "Could not determine a valid input file type",
+            error:   "Could not determine a valid input file type",
+        })
+    }
+
+    // Check if we have the target Format
+    const targetFormat = req.body.targetFormat
+
+    // Predefine the result
+    let result: string | null = null;
+
+    // Check for the input/output formats
+    if ( targetFormat == 'png' && inputFileType == 'application/pdf' ) {
+        await convertFileToPNG(inputFile)
+        .then( data => {
+            result = data.toString(`base64`);
+        })
+        .catch( err => {
+            console.error(err);
+        })
+    }
+
+    res.status(200).send({
+        message: `Conversion completed`,
+        result: result,
+    });
+
+}
+
+export { convertController }

src/Controllers/Homepage.ts

@@ -1,6 +1,6 @@
 import { Request, Response, NextFunction, Router } from 'express';
 
-const homepageController = ( req:Request, res:Response, next:NextFunction ) => {
+const homepageController = ( req: Request, res: Response, next: NextFunction ) => {
 
     // Make sure that the browser isn't caching this
     res.setHeader(`Cache-Control`, `no-cache, must-revalidate`);

src/Helpers/ApiHelper.ts

@@ -0,0 +1,19 @@
+import { Response } from "express";
+
+export function returnError(res: Response, content: any, status: number = 400) {
+    res.status(status).send(content);
+}
+
+export function findFile(fieldName: string, fileList: Express.Multer.File[]): Express.Multer.File | null {
+
+    // Go through all files
+    for ( let file of fileList ) {
+        // Check if the field name matches
+        if ( file.fieldname == fieldName) {
+            // Return the found file
+            return file;
+        }
+    }
+
+    return null;
+}

src/Models/ConversionModel.ts

@@ -0,0 +1,36 @@
+import { Poppler } from "node-poppler";
+import fs from "fs/promises";
+
+
+export function convertFileToPNG(file: Express.Multer.File): Promise<Buffer> {
+
+    return new Promise<Buffer>((_r, _e) => {
+
+        console.log(file);
+        // Read the file
+        fs.readFile(file.path)
+        .then( fileBuffer => {
+            let p = new Poppler(`/usr/bin`);
+            p.pdfToCairo(fileBuffer, undefined, {
+                pngFile: true,
+                singleFile: true,
+            })
+            .then( buff => {
+
+                if ( buff instanceof Error ) {
+                    return _e(buff);
+                }
+
+                _r(Buffer.from(buff));
+            })
+            .catch(err => {
+                _e(err);
+            })
+        })
+        .catch( err => {
+            return _e(err);
+        })
+
+    })
+
+}

src/Routes/Api.ts

@@ -0,0 +1,23 @@
+// Imports
+import express from 'express';
+import multer from 'multer';
+import { convertController } from '../Controllers/Convert';
+
+const upload = multer({ dest: '/tmp' });
+
+// Get the router
+const router = express.Router();
+
+router.get(`/`, (req, res, next) => {
+    res.status(200).send({
+        status: "Healthy",
+        healthStatus: "100%",
+        version: "1.0.0",
+    });
+})
+
+// Set the route
+router.post("/convert", upload.any(), convertController);
+
+// Export the reouter
+export {router as apiRouter};

src/app.ts

@@ -4,6 +4,7 @@ import express from 'express';
 import config from './Config/config';
 import { engine } from 'express-handlebars';
 import { homepageRouter } from './Routes/Homepage';
+import { apiRouter } from './Routes/Api';
 
 //#endregion
 
@@ -58,6 +59,8 @@ router.use((req, res, next) => {
 router.use(`/public`, express.static('./src/public/'));
 
 // Handle the homepage
+router.use("/api", apiRouter);
+
 router.get("/", homepageRouter);
 
 { // Error handling