reception.js

const express = require('express');
const mongoose = require('mongoose');
const fs = require('fs');
const envUtils = require('../helpers/envutils');
const crypto = require("crypto");

const router = express.Router();

//import models
require('../models/HttpDump');
require('../models/HttpReception');

const HttpDump = mongoose.model('httdump');
const HttpReception = mongoose.model('httpreception')
//routes

router.get("/:id", (req, res) => {
    handleRequest(req, res, "GET");
});

router.post("/:id", (req, res) => {
    handleRequest(req, res, "POST");
});

router.put("/:id", (req, res) => {
    handleRequest(req, res, "PUT");
});

router.delete("/:id", (req, res) => {
    handleRequest(req, res, "DELETE");
});

//route for downloading request payload
router.get("/download/requestpayload/:id", (req, res) => {
    handleDownload(req, res, true);
});

//route for fownloading reesponse payload
router.get("/download/responsepayload/:id", (req, res) => {
    handleDownload(req, res, false);
});

//end of routes

function handleRequest(req, res, method) {
    HttpReception.findById({
        _id: req.params.id
    })
        .then(httpReception => {
            if (httpReception != null) {
                processRequest(req, res, method, httpReception);
            } else {
                res.send("HTTP Reception is not defined or expired!");
            }
        })
        .catch(err => {
            console.log(err);
            res.send("Error Occured!");
        });
}

function processRequest(req, res, method, httpReception) {
    const headers = req.headers
    const headerMap = [];

    for (var key in headers) {
        //headerMap.set(key, headers[key]);
        headerMap.push({
            key: key,
            value: headers[key]
        })
    }
    let chunks = [];
    let finalBuffer;

    //record request body
    req.on('data', chunk => {
        chunks.push(chunk);
    }).on('end', () => {//received all the data from the request
        finalBuffer = Buffer.concat(chunks);
        //headers to be sent
        const responseHeaders = [];
        var idx = 0;
        for (; idx < httpReception.responseHeaders.length; idx++) {
            const headerKey = httpReception.responseHeaders[idx].key;
            const headerVal = httpReception.responseHeaders[idx].value;
            responseHeaders.push({
                key: headerKey,
                value: headerVal
            });
        }

        //persist
        const newHttpDump = {
            host: req.hostname,
            ip: req.ip,
            protocol: req.protocol,
            method: method,
            body: finalBuffer,
            responseBody: httpReception.body,
            headers: headerMap,
            responseHeaders: responseHeaders,
            httpReceptionId: httpReception._id
        };

        new HttpDump(newHttpDump).
            save()
            .then(httpdmp => {
                var idx = 0;
                for (; idx < responseHeaders.length; idx++) {
                    const headerKey = responseHeaders[idx].key;
                    const headerVal = responseHeaders[idx].value;
                    res.setHeader(headerKey, headerVal);
                }
                res.writeHead(httpReception.responseStatus, httpReception.reasonPhrase);
                res.end(httpReception.body);
            })
            .catch(err => {
                console.log(err);
                res.send("Error occured " + err)
            });

    });
}

//handle common download request
function handleDownload(req, res, isRequestDownload) {
    HttpDump.findById({
        _id: req.params.id
    })
        .then(httpdmp => {
            var buffer;
            if(isRequestDownload){
                buffer = httpdmp.body;
            }else{
                buffer = httpdmp.responseBody;
            }

            //write response payload to temp location
            const randomFileName = crypto.randomBytes(16).toString("hex");
            const filePath = envUtils.getTempDir() + randomFileName;
            fs.writeFile(filePath, buffer, (err) => {
                if (err) {
                    res.send("Unable to write file");
                }
                else {
                    //download written file
                    res.download(filePath, randomFileName, (err) => {
                        if (err) {
                            res.send("Unable to download file!");
                        }
                        //try to delete temp file
                        fs.unlinkSync(filePath);
                    });
                }
            });
        })
        .catch(err => {
            res.send("Error when retrieving http dump");
        });
}

module.exports = router;