package nostr

import (
	"context"
	b64 "encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strings"
	"time"

	"git.minhas.io/asara/well-goknown/lnd"
	"git.minhas.io/asara/well-goknown/logger"
	"git.minhas.io/asara/well-goknown/redis"
	"github.com/nbd-wtf/go-nostr/nip19"
	"github.com/skip2/go-qrcode"
)

type nostrWellKnown struct {
	Names  map[string]string   `json:"names"`
	Relays map[string][]string `json:"relays,omitempty"`
}

type jsonErrorMessage struct {
	Error string `json:"error"`
}

type NostrRequest struct {
	Name     string `json:"name"`
	Key      string `json:"key"`
	Hostname string
	Relays   []string `json:"relays,omitempty"`
}

func RequestNostrAddr(w http.ResponseWriter, r *http.Request) {
	ctx := context.TODO()
	l := logger.Get()
	switch r.Method {
	case "GET":
		http.ServeFile(w, r, "html/nostr_form.html")
	case "POST":
		r.ParseForm()
		redisCli := redis.NostrRedisConn.Client
		// check if the user already exists
		rKey := getRkey("verified", r.FormValue("Name"), getHostname(r.Host))
		exists := redisCli.Exists(ctx, rKey)
		if exists.Val() == 1 {
			w.WriteHeader(http.StatusConflict)
			json.NewEncoder(w).Encode(&jsonErrorMessage{
				Error: "username already registered",
			})
			return
		}
		rKey = getRkey("requested", r.FormValue("Name"), getHostname(r.Host))
		exists = redisCli.Exists(ctx, rKey)
		if exists.Val() == 1 {
			w.WriteHeader(http.StatusConflict)
			json.NewEncoder(w).Encode(&jsonErrorMessage{
				Error: "username already requested, try again in a few minutes",
			})
			return
		}

		// get the hexkey
		hexKey, err := convertNpubToHex(r.FormValue("Key"))
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			json.NewEncoder(w).Encode(&jsonErrorMessage{
				Error: err.Error(),
			})
			return
		}

		// create the struct
		relays := make(map[string][]string)
		names := map[string]string{r.FormValue("Name"): hexKey}
		user := nostrWellKnown{}
		if r.FormValue("Relays") != "" {
			relays = map[string][]string{
				hexKey: strings.Split(r.FormValue("Relays"), ","),
			}
			user = nostrWellKnown{Names: names, Relays: relays}
		} else {
			user = nostrWellKnown{Names: names}
		}
		jsonUser, _ := json.Marshal(user)
		enc := b64.StdEncoding.EncodeToString([]byte(jsonUser))

		// generate the payment request
		paymentReq, err := lnd.Request(rKey)
		if err != nil {
			w.WriteHeader(http.StatusServiceUnavailable)
			json.NewEncoder(w).Encode(&jsonErrorMessage{
				Error: "service unavailable",
			})
			return
		}

		// generate qr png
		png, err := qrcode.Encode(paymentReq, qrcode.Medium, 256)

		// write request to redis
		err = redisCli.Set(ctx, rKey, enc, 15*time.Minute).Err()
		if err != nil {
			l.Error().Msg("unable to connect to redis")
		}

		// return qr code
		w.Header().Set("Content-Type", "image/png")
		w.WriteHeader(http.StatusOK)
		w.Write(png)
	}
}

func GetNostrAddr(w http.ResponseWriter, r *http.Request) {
	ctx := context.TODO()
	// get query string for username
	r.ParseForm()
	requestedName := r.FormValue("name")

	// connect to redis
	redisCli := redis.NostrRedisConn.Client

	// search for user@domain
	search := getRkey("verified", requestedName, getHostname(r.Host))
	addr, err := redisCli.Get(ctx, search).Result()
	if err != nil {
		w.WriteHeader(http.StatusNotFound)
		json.NewEncoder(w).Encode(&jsonErrorMessage{
			Error: "username not registered",
		})
		return
	}
	dec, err := b64.StdEncoding.DecodeString(addr)
	if err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		json.NewEncoder(w).Encode(&jsonErrorMessage{
			Error: "internal server error",
		})
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	w.Write(dec)
}

func AddNostrAddr(n NostrRequest) {
	ctx := context.TODO()
	l := logger.Get()
	// transform request to well known struct
	relays := make(map[string][]string)
	user := nostrWellKnown{}
	hexKey, err := convertNpubToHex(n.Key)
	if err != nil {
		l.Error().Msg("unable to convert npub to hex")
	}
	names := map[string]string{n.Name: hexKey}

	if n.Relays != nil {
		relays = map[string][]string{hexKey: n.Relays}
		user = nostrWellKnown{Names: names, Relays: relays}
	} else {
		user = nostrWellKnown{Names: names}
	}
	jsonUser, _ := json.Marshal(user)

	redisCli := redis.NostrRedisConn.Client
	nameKey := getRkey("verified", n.Name, n.Hostname)
	enc := b64.StdEncoding.EncodeToString([]byte(jsonUser))
	err = redisCli.Set(ctx, nameKey, enc, 0).Err()
	if err != nil {
		l.Error().Msg("unable to connect to redis")
	}
}

func getHostname(hostname string) string {
	// remove port for local testing
	return hostname
}

func convertNpubToHex(npub string) (string, error) {
	if !strings.HasPrefix(npub, "npub1") {
		return "", errors.New("key does not start with npub1 prefix")
	}
	_, hex, err := nip19.Decode(npub)
	if err != nil {
		return "", errors.New("unable to decode npub key")
	}

	return hex.(string), nil

}

func getRkey(prefix string, user string, hostname string) string {
	if strings.Contains(hostname, ":") {
		hostname = strings.Split(hostname, ":")[0]
	}
	return fmt.Sprintf("%s:%s@%s", prefix, user, hostname)
}