package oidc

import (
	"encoding/gob"
	"net/http"

	"github.com/coreos/go-oidc"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
	"gitlab.com/wpetit/goweb/middleware/container"
	"gitlab.com/wpetit/goweb/service/session"
)

const (
	SessionIDTokenKey   = "oidc-id-token"
	SessionOIDCStateKey = "oidc-state"
	SessionOIDCNonceKey = "oidc-nonce"
)

func init() {
	gob.Register(&oidc.IDToken{})
}

func Middleware(next http.Handler) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		if _, err := IDToken(w, r); err != nil {
			logger.Error(r.Context(), "could not retrieve idtoken", logger.E(errors.WithStack(err)))

			ctn := container.Must(r.Context())
			client := Must(ctn)
			client.Login(w, r)
			return
		}

		next.ServeHTTP(w, r)
	}

	return http.HandlerFunc(fn)
}

func HandleCallback(next http.Handler) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()
		ctn := container.Must(ctx)
		client := Must(ctn)

		_, rawIDToken, err := client.Validate(w, r)
		if err != nil {
			logger.Error(ctx, "could not validate oidc token", logger.E(errors.WithStack(err)))

			http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)

			return
		}

		sess, err := session.Must(ctn).Get(w, r)
		if err != nil {
			panic(errors.Wrap(err, "could not retrieve session"))
		}

		sess.Set(SessionIDTokenKey, rawIDToken)

		if err := sess.Save(w, r); err != nil {
			panic(errors.Wrap(err, "could not save session"))
		}

		next.ServeHTTP(w, r)
	}

	return http.HandlerFunc(fn)
}

func RawIDToken(w http.ResponseWriter, r *http.Request) (string, error) {
	ctx := r.Context()

	ctn, err := container.From(ctx)
	if err != nil {
		return "", errors.Wrap(err, "could not retrieve service container")
	}

	sess, err := session.Must(ctn).Get(w, r)
	if err != nil {
		return "", errors.Wrap(err, "could not retrieve session")
	}

	rawIDToken, ok := sess.Get(SessionIDTokenKey).(string)
	if !ok || rawIDToken == "" {
		return "", errors.New("invalid id token")
	}

	return rawIDToken, nil
}

func IDToken(w http.ResponseWriter, r *http.Request) (*oidc.IDToken, error) {
	rawIDToken, err := RawIDToken(w, r)
	if err != nil {
		return nil, errors.Wrap(err, "could not retrieve raw idtoken")
	}

	ctx := r.Context()
	ctn, err := container.From(ctx)
	if err != nil {
		return nil, errors.Wrap(err, "could not retrieve service container")
	}

	client, err := From(ctn)
	if err != nil {
		return nil, errors.Wrap(err, "could not retrieve oidc service")
	}

	idToken, err := client.verifier.Verify(ctx, rawIDToken)
	if err != nil {
		return nil, errors.Wrap(err, "could not verify id token")
	}

	return idToken, nil
}