package main

import (
	"context"
	"encoding/hex"
	"flag"
	"net/http"
	"time"

	"github.com/google/uuid"
	"github.com/o1egl/paseto/v2"
	"golang.org/x/crypto/ed25519"
	"golang.org/x/net/trace"
)

var (
	// Paseto
	pasetoPublicKey  = flag.String("paseto-public-key", "", "Paseto public key (see tools/paseto-key-gen.go)")
	pasetoPrivateKey = flag.String("paseto-private-key", "", "Paseto private key")
)

type GoTraceMiddleware struct{ next http.Handler }

func (gtm GoTraceMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()
	tr := trace.New("http", r.URL.Path)
	ctx = trace.NewContext(ctx, tr)
	r = r.WithContext(ctx)
	gtm.next.ServeHTTP(w, r)
	tr.Finish()
}

type PasetoMiddleware struct {
	next    http.Handler
	pubKey  ed25519.PublicKey
	privKey ed25519.PrivateKey
	v2      paseto.V2
}

func MakeMiddleware(pub, priv string, next http.Handler) (*PasetoMiddleware, error) {
	var result PasetoMiddleware
	result.next = next

	publicKey, err := hex.DecodeString(pub)
	if err != nil {
		return nil, err
	}
	result.pubKey = ed25519.PublicKey(publicKey)

	privateKey, err := hex.DecodeString(priv)
	if err != nil {
		return nil, err
	}
	result.privKey = ed25519.PrivateKey(privateKey)

	return &result, nil
}

func (pm PasetoMiddleware) CreateToken(data [][2]string, expiration time.Time) (string, error) {
	claims := paseto.JSONToken{
		Expiration: expiration,
		Jti:        uuid.New().String(),
		Subject:    "Within",
		IssuedAt:   time.Now(),
	}

	for _, datum := range data {
		claims.Set(datum[0], datum[1])
	}

	tok, err := pm.v2.Sign(pm.privKey, claims, nil)
	if err != nil {
		return "", err
	}

	return tok, nil
}

var publicRoutes map[string]bool

func init() {
	publicRoutes = map[string]bool{
		"/webhooks/":          true,
		"/static/":            true,
		"/static/main.js":     true,
		"/static/gruvbox.css": true,
		"/static/favicon.ico": true,
		"/static/favicon.png": true,
		"/debug/requests":     true,
		"/debug/events":       true,
	}
}

type ctxKey int

const (
	tokenKey ctxKey = iota
)

func (pm PasetoMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	tok := r.Header.Get("Authorization")
	var newJsonToken paseto.JSONToken
	var newFooter string
	var err error

	if r.URL.EscapedPath() == "/.within/botinfo" || r.URL.EscapedPath() == "/" {
		goto ok
	}

	for k := range publicRoutes {
		if r.URL.EscapedPath() == k {
			goto ok
		}
	}

	err = pm.v2.Verify(tok, pm.pubKey, &newJsonToken, &newFooter)
	if err != nil {
		http.Error(w, "Not allowed", http.StatusForbidden)
		return
	}

	r = r.WithContext(context.WithValue(r.Context(), tokenKey, newJsonToken))

ok:
	pm.next.ServeHTTP(w, r)
}