// Install node-http-proxy package first
var http = require("http"), httpProxy = require("http-proxy");

var API_TARGET = 'https://pokeapi.co/api/v2/'
var PROXY_PORT = 8080

// Create a proxy server with custom application logic
var proxy = httpProxy.createProxyServer({});
var sendError = function(res, err) {
        return res.status(500).send({
                 error: err,
                 message: "An error occured in the proxy"
        });
};

// error handling
proxy.on("error", function (err, req, res) {
        sendError(res, err);
});

var enableCors = function(req, res) {
        if (req.headers['access-control-request-method']) {
                res.setHeader('access-control-allow-methods', req.headers['access-control-request-method']);
        }

	if (req.headers['access-control-request-headers']) {
                res.setHeader('access-control-allow-headers', req.headers['access-control-request-headers']);
        }

	if (req.headers.origin) {
                res.setHeader('access-control-allow-origin', req.headers.origin);
                res.setHeader('access-control-allow-credentials', 'true');
        }
};

// set header for CORS
proxy.on("proxyRes", function(proxyRes, req, res) {
        enableCors(req, res);
});

var server = http.createServer(function(req, res) {
        // You can define here your custom logic to handle the request
        // and then proxy the request.
        if (req.method === 'OPTIONS') {
                enableCors(req, res);
                res.writeHead(200);
                res.end();
                return;
        }

	proxy.web(req, res, {
                target: API_TARGET,
                secure: true,
                changeOrigin: true
        }, function(err) {
                sendError(res, err);
        });
});

server.listen(PROXY_PORT);