/*
Command simController is the controller end of a simulated dial-out switch configuration service.

It is an upstream http://localhost:8080 server. It requires an NginX reverse proxy that presents its protocol as
an HTTP2, mutual auth service on https://localcalhost:8443.

NginX is expected to support switch configuration HTTP2 clients and multiplex their concurrent requests over a single TLS session.

NginX will then spread client requests across one or more config servers. Each active request will be carried
on a separate TCP connection.
*/
package main

import (
	"log"
	"net/http"
	"net/url"
	"time"
)

const (

	//The port this program presents its HTTP service on
	port = "8080"
)

//handlePing is the http handler for /config requests
func handlePing(w http.ResponseWriter, r *http.Request) {
	var (
		pingQueryValues url.Values
		pingInterval    string
		interval        time.Duration
		err             error
	)

	//The interval query parameter specifies the number of seconds to delay responding to the ping. If none, ping is immediate.
	pingQueryValues, err = url.ParseQuery(r.URL.RawQuery)
	if err != nil {
		log.Printf("Ping request query string error: %s\n", err)
		w.WriteHeader(http.StatusBadRequest)
		return
	}
	pingInterval = pingQueryValues.Get("interval")
	if pingInterval == "" {
		log.Println("Responded immediately to Ping")
		return
	} else {
		interval, err = time.ParseDuration(pingInterval + "s")
		if err != nil {
			log.Printf("Ping interval conversion error: %s\n", err)
			w.WriteHeader(http.StatusBadRequest)
			return
		}
		time.Sleep(interval)
		log.Printf("Responded to Ping after %s seconds\n", pingInterval)
	}
} //handlePing

func main() {
	var (
		err error
	)

	//Start the simController service
	log.Printf("Starting the simController service on port %s", port)
	http.HandleFunc("/ping", handlePing)
	err = http.ListenAndServe(":"+port, nil)
	log.Printf("The simController service terminated with status: %s\n", err)

}