package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"os"
	"time"
)
func init() {
	const usageHeader = `
simple golang http server to log http request bodies and parameters; can optionally respond with static file content

author: heqnx - https://heqnx.com

`
	flag.Usage = func() {
		fmt.Fprint(os.Stderr, usageHeader)
		fmt.Fprintf(os.Stderr, "usage of %s:\n", os.Args[0])
		flag.PrintDefaults()
	}
	flag.CommandLine.SetOutput(os.Stderr)
}

func main() {
	listen := flag.String("listen", "0.0.0.0", "interface to listen on (default: 0.0.0.0)")
	port := flag.String("port", "8080", "port to listen on")
	cert := flag.String("cert", "", "tls certificate file (for https)")
	key := flag.String("key", "", "tls key file (for https)")
	responseFile := flag.String("response", "", "file to use as static HTTP response body")
	flag.Parse()

	if flag.NFlag() == 0 && flag.NArg() == 0 {
		flag.Usage()
		os.Exit(1)
	}

	logFilename := fmt.Sprintf("requests_%s.log", time.Now().Format("2006-01-02T15-04-05"))
	logFile, err := os.OpenFile(logFilename, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
	if err != nil {
		fmt.Printf("[err] filed to open log file: %v\n", err)
	}
	defer logFile.Close()

	multiLog := io.MultiWriter(os.Stdout, logFile)
	logger := log.New(multiLog, "", 0)

	var staticResponse []byte
	if *responseFile != "" {
		staticResponse, err = os.ReadFile(*responseFile)
		if err != nil {
			fmt.Printf("[err] failed to read response file: %v\n", err)
		}
	}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		body, _ := io.ReadAll(r.Body)
		r.Body.Close()

		host, _, err := net.SplitHostPort(r.RemoteAddr)
		if err != nil {
			host = r.RemoteAddr
		}
		logger.Printf("%s | %s\n", time.Now().Format("2006/01/02 15:04:05"), host)

		var logEntry string
		logEntry += fmt.Sprintf("%s %s %s\n", r.Method, r.URL.RequestURI(), r.Proto)
		if r.Host != "" {
			logEntry += fmt.Sprintf("Host: %s\n", r.Host)
		}
		for name, values := range r.Header {
			for _, value := range values {
				logEntry += fmt.Sprintf("%s: %s\n", name, value)
			}
		}

		logEntry += "\n" + string(body) + "\n\n---\n\n"
		logger.Print(logEntry)

		w.WriteHeader(http.StatusOK)
		if staticResponse != nil {
			_, _ = w.Write(staticResponse)
		} else {
			_, _ = w.Write([]byte("pong\n"))
		}
	})

	addr := *listen + ":" + *port

	if *cert != "" && *key != "" {
		logger.Printf("[inf] starting https server on %s\n", addr)
		err = http.ListenAndServeTLS(addr, *cert, *key, nil)
	} else {
		logger.Printf("[inf] starting http server on %s\n", addr)
		err = http.ListenAndServe(addr, nil)
	}

	if err != nil {
		fmt.Printf("[err] server failed: %v\n", err)
	}
}