package auth

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"ruben/inventory2/internal/domains/authentication"
	"ruben/inventory2/internal/server/cookies"
	"ruben/inventory2/internal/server/response"
	"ruben/inventory2/internal/server/router"
)

type loginSubrouter struct {
	log  *slog.Logger
	auth *authentication.Authenticator
	router.Subrouter
}

func NewLoginSubrouter(logger *slog.Logger, auth *authentication.Authenticator) *loginSubrouter {
	mux := router.NewSubMux(logger)

	ls := &loginSubrouter{
		log:       logger,
		auth:      auth,
		Subrouter: mux,
	}

	mux.Handle("GET /login", ls.loginPage)
	mux.Handle("GET /login/callback", ls.loginCallback)
	mux.Handle("GET /logout", ls.logoutPage)

	return ls
}

func (s *loginSubrouter) newLoginSubrouter(logger *slog.Logger) router.Subrouter {
	mux := router.NewSubMux(logger)

	ls := &loginSubrouter{
		log:       s.log,
		auth:      s.auth,
		Subrouter: mux,
	}

	mux.Handle("GET /login", ls.loginPage)
	mux.Handle("GET /login/callback", ls.loginCallback)
	mux.Handle("GET /logout", ls.logoutPage)

	return ls
}

func (s *loginSubrouter) loginPage(r *http.Request) (response.Response, error) {
	ctx := r.Context()

	u, err := NewLoginURL(ctx, s.auth, "/")
	if err != nil {
		return nil, err
	}

	return response.TemporaryRedirect(u), nil
}

func NewLoginURL(ctx context.Context, auth *authentication.Authenticator, targetURI string) (string, error) {
	state, err := auth.NewState(ctx, targetURI)
	if err != nil {
		return "", fmt.Errorf("failed to generate random state: %w", err)
	}

	base64EncodedState := fmt.Sprintf("%x", state[:])

	return auth.AuthCodeURL(base64EncodedState), nil
}

func (s *loginSubrouter) loginCallback(r *http.Request) (response.Response, error) {
	ctx := r.Context()
	q := r.URL.Query()

	// obtain token and profile

	accessToken, targetURI, expiration, err := s.auth.Exchange(ctx, q.Get("state"), q.Get("code"))
	if err != nil {
		return nil, response.Unauthorized().
			Msg(fmt.Sprintf("Failed to exchange an authorization code for a token")).
			Wrap(err)
	}

	// set access_token cookie and redirect to a reasonable place

	return response.TemporaryRedirect(targetURI).
		Cookie(cookies.AccessToken(accessToken, expiration)), nil
}

func (s *loginSubrouter) logoutPage(r *http.Request) (response.Response, error) {
	host := r.Header.Get("X-Forwarded-Host")
	if host == "" {
		host = r.Host
	}

	if ck, err := r.Cookie("access_token"); err == nil && ck != nil {
		if err := s.auth.DeleteOAuthTokens(r.Context(), ck.Value); err != nil {
			s.log.Error("failed to delete auth token", "error", err)
		}
	}

	return response.TemporaryRedirect(s.auth.GetLogoutURL(host).String()).
		Cookie(cookies.Expired("access_token")), nil
}