package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"os"
	"os/signal"
	"path"
	"strings"
	"syscall"
)

var myLDAP = LDAP{
	Host:   "localhost",
	Port:   389,
	BaseDN: "dc=example,dc=com",
}

type ResponseWriterPrefix struct {
	real   http.ResponseWriter
	prefix string
}

func (r ResponseWriterPrefix) Header() http.Header {
	return r.real.Header()
}

func (r ResponseWriterPrefix) WriteHeader(s int) {
	if v, exists := r.real.Header()["Location"]; exists {
		r.real.Header().Set("Location", r.prefix+v[0])
	}
	r.real.WriteHeader(s)
}

func (r ResponseWriterPrefix) Write(z []byte) (int, error) {
	return r.real.Write(z)
}

func StripPrefix(prefix string, h http.Handler) http.Handler {
	if prefix == "" {
		return h
	}
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if prefix != "/" && r.URL.Path == "/" {
			http.Redirect(w, r, prefix+"/", http.StatusFound)
		} else if p := strings.TrimPrefix(r.URL.Path, prefix); len(p) < len(r.URL.Path) {
			r2 := new(http.Request)
			*r2 = *r
			r2.URL = new(url.URL)
			*r2.URL = *r.URL
			r2.URL.Path = p
			h.ServeHTTP(ResponseWriterPrefix{w, prefix}, r2)
		} else {
			h.ServeHTTP(w, r)
		}
	})
}

func main() {
	var bind = flag.String("bind", "127.0.0.1:8080", "Bind port/socket")
	var baseURL = flag.String("baseurl", "/", "URL prepended to each URL")
	var configfile = flag.String("config", "config.json", "path to the configuration file")
	flag.Parse()

	// Sanitize options
	log.Println("Checking paths...")
	if *baseURL != "/" {
		tmp := path.Clean(*baseURL)
		baseURL = &tmp
	} else {
		tmp := ""
		baseURL = &tmp
	}

	// Load config file
	if fd, err := os.Open(*configfile); err != nil {
		log.Fatal(err)
	} else if cnt, err := ioutil.ReadAll(fd); err != nil {
		log.Fatal(err)
	} else if err := json.Unmarshal(cnt, &myLDAP); err != nil {
		log.Fatal(err)
	}

	// Prepare graceful shutdown
	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt, syscall.SIGTERM)

	// Register handlers
	http.HandleFunc(fmt.Sprintf("%s/", *baseURL), changePassword)
	http.HandleFunc(fmt.Sprintf("%s/login", *baseURL), tryLogin)
	http.HandleFunc(fmt.Sprintf("%s/change", *baseURL), changePassword)
	http.HandleFunc(fmt.Sprintf("%s/reset", *baseURL), resetPassword)
	http.HandleFunc(fmt.Sprintf("%s/lost", *baseURL), lostPassword)

	srv := &http.Server{
		Addr: *bind,
	}

	// Serve content
	go func() {
		log.Fatal(srv.ListenAndServe())
	}()
	log.Println(fmt.Sprintf("Ready, listening on %s", *bind))

	// Wait shutdown signal
	<-interrupt

	log.Print("The service is shutting down...")
	srv.Shutdown(context.Background())
	log.Println("done")
}