package main

import (
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strings"
)

func mustGetEnv(env string) (val string) {
	val, ok := os.LookupEnv(env)
	if !ok {
		log.Fatalf("required env var %s not found", env)
	}
	return
}

var host string
var fullhost string
var prefix *string

func main() {
	prefix = flag.String("prefix", "AW_", "Environment var prefix")
	proto := flag.String("proto", "https", "Protocol under which this server is going to be exposed")
	flag.Parse()

	bind, ok := os.LookupEnv(*prefix + "BIND")
	if !ok {
		bind = ":8080" // Default to *:8080
	}

	host = strings.ToLower(mustGetEnv(*prefix + "HOST"))
	fullhost = fmt.Sprintf("%s://%s", *proto, host)

	discoverApps()

	http.HandleFunc("/.well-known/host-meta", hostMetaHandler)
	http.HandleFunc("/.well-known/webfinger", handlerWebFinger)
	http.HandleFunc("/u/", handlerUserPage)
	http.HandleFunc("/inbox", func(w http.ResponseWriter, r *http.Request) {
		byt, _ := ioutil.ReadAll(r.Body)
		fmt.Println(string(byt))
	})

	if err := http.ListenAndServe(bind, nil); err != nil {
		log.Fatalf("error while listening: %f", err)
	}
}

func discoverApps() {
	// Find app definitions
	envs := os.Environ()
	envAppPrefix := *prefix + "APP_"
	envAppPrefixLen := len(envAppPrefix)
	apps = make(map[string]appDef)
	for _, envName := range envs {
		// Filter for APP_* vars
		if !strings.HasPrefix(envName, envAppPrefix) {
			continue
		}
		// Retrieve app name
		nextSep := strings.Index(envName[envAppPrefixLen:], "_")
		if nextSep < 0 {
			nextSep = 0
		}
		name := envName[envAppPrefixLen : envAppPrefixLen+nextSep]
		appName := strings.ToLower(name)
		// Skip if we processed this app already
		if _, ok := apps[appName]; ok {
			continue
		}
		// Retrieve info for app
		var pubkey *rsa.PublicKey = nil
		if key, ok := os.LookupEnv(envAppPrefix + name + "_PEM"); ok {
			key, _ := pem.Decode([]byte(key))
			pub, err := x509.ParsePKCS1PublicKey(key.Bytes)
			if err != nil {
				log.Fatalf("Error while parsing PEM/PKCS1 block for %s: %s", envAppPrefix+name+"_PEM", err.Error())
			}
			pubkey = pub
		}

		apps[appName] = appDef{
			Name:       mustGetEnv(envAppPrefix + name + "_NAME"),
			WebhookURL: mustGetEnv(envAppPrefix + name + "_URL"),
			PublicKey:  pubkey,
		}

		log.Printf("app registered: %s", appName)
	}
}