package main

import (
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"os"

	"github.com/urfave/cli"
)

func main() {
	app := cli.NewApp()
	app.Name = "what-is-my-ip"
	app.Version = "0.2.0"
	app.Usage = "Webapp that gives the IP address for incoming requests"
	app.Action = action

	app.Flags = []cli.Flag{
		cli.StringFlag{
			Name:   "address, a",
			Value:  ":3000",
			EnvVar: "WHAT_IS_MY_IP_ADDRESS",
			Usage:  "Address and port to bind to",
		},

		cli.StringFlag{
			Name:   "certificate, c",
			Value:  "cert.pem",
			EnvVar: "WHAT_IS_MY_IP_CERTIFICATE",
			Usage:  "path to certificate file for https server",
		},

		cli.StringFlag{
			Name:   "key, k",
			Value:  "key.pem",
			EnvVar: "WHAT_IS_MY_IP_KEY",
			Usage:  "path to key file for https server",
		},
	}

	app.Run(os.Args)
}

func action(c *cli.Context) error {
	http.HandleFunc("/", getIP)
	address := c.String("address")
	certificate := c.String("certificate")
	key := c.String("key")
	fmt.Printf("listening on %s\n", address)
	return http.ListenAndServeTLS(address, certificate, key, nil)
}

func getIP(w http.ResponseWriter, req *http.Request) {
	ip, _, err := net.SplitHostPort(req.RemoteAddr)
	if err != nil {
		handleError(w, err, "Could not get IP address from request")
		return
	}
	io.WriteString(w, ip+"\n")
	log.Printf("Give response IP %s\n", ip)
}

func handleError(resp http.ResponseWriter, err error, message string) {
	resp.WriteHeader(http.StatusBadRequest)
	io.WriteString(resp, message)
	log.Printf("Error handling request: %s (%s)", message, err)
}