content-type-router/content-type-router.js

This is a strictly structured router module designed for internal use only. It assumes all incoming request are either json, text or file/blob via POST method. It doesn't parse flexible parameter in path either.

'use strict';
async function init(req, res, env, map) {
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.setHeader('Access-Control-Allow-Methods', 'POST, GET, OPTIONS');
    res.setHeader('Access-Control-Allow-Credentials', false);
    res.setHeader('Access-Control-Max-Age', '3600');
    res.setHeader('Access-Control-Allow-Headers', 'Origin, Content-Type, Accept, Authorization');
    if (map[req.url]) {
        switch (req.method) {
            case 'OPTIONS':
                res.statusCode = 200;
                res.end();
                break;
            case 'GET':
                map[req.url](req, res, env);
                break;
            case 'POST':
                switch (req.headers['content-type']) {
                    case 'application/json':
                        {
                            let json = await processJson(req, res);
                            await map[req.url](req, res, env, json);
                            break;
                        }
                    case 'undefined':
                    case 'null':
                    case '':
                    case undefined:
                    case null:
                        res.statusCode = 406;
                        res.statusMessage = "The provided content MIME type is not acceptable";
                        res.end();
                        break;
                    default:
                        {
                            let file = await processFile(req, res);
                            await map[req.url](req, res, env, file);
                            break;
                        }
                }
                break;
            default:
                res.statusCode = 406;
                res.statusMessage = "The provided method is not acceptable";
                res.end();
        }
    } else {
        res.statusCode = 404;
        res.statusMessage = "Service does not exist";
        res.end();
    }
}
async function processJson(req, res) {
    return new Promise(function(resolve, reject) {
        try {
            let text = '';
            let json = {};
            req.on('data', (chunk) => {
                text += chunk;
            });
            req.on('end', () => {
                json = JSON.parse(text) || {};
                resolve(json);
            });
        } catch (e) {
            res.statusCode = 406;
            res.statusMessage = "The incoming JSON string is invalid";
            res.end();
            reject(e);
        }
    });
}
async function processFile(req, res) {
    return new Promise(function(resolve, reject) {
        try {
            let buffer = Buffer.alloc(0);
            req.on('data', (chunk) => {
                buffer = Buffer.concat([buffer, chunk]);
            });
            req.on('end', () => {
                let file = {
                    buffer: buffer,
                    contentType: req.headers['content-type'],
                    contentCategory: req.headers['content-type'].split('/')[0]
                };
                resolve(file);
            });
        } catch (e) {
            res.statusCode = 500;
            res.statusMessage = "Something goes wrong while parsing FILE";
            res.end();
            reject(e);
        }
    });
}
exports.init = init;