package login

import (
	"errors"
	"fmt"
	"net/http"

	"github.com/rs/zerolog/log"

	"librapi/forms"
	"librapi/services"
	"librapi/templates"
)

const URL = "/login"

func Handler(a services.IAuthenticate) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		switch r.Method {
		case http.MethodGet:
			getLogin(w, r, a)
		case http.MethodPost:
			postLogin(w, r, a)
		default:
			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		}
	}
}

func postLogin(w http.ResponseWriter, r *http.Request, a services.IAuthenticate) {
	if a.IsLogged(r) {
		tmpl, err := templates.ExecuteLoginSuccessTmpl(w)
		if err != nil {
			log.Err(err).Msg("unable to generate login success template")
			return
		}
		fmt.Fprint(w, tmpl)
		return
	}

	lf := forms.LoginFormFromRequest(r)
	if lf.HasErrors() {
		tmpl, err := templates.ExecuteLoginFormTmpl(&lf, w)
		if err != nil {
			log.Err(err).Msg("unable to generate login form template")
			return
		}

		w.WriteHeader(http.StatusBadRequest)
		fmt.Fprint(w, tmpl)
		return
	}

	session, err := a.Authenticate(lf.Username.Value, lf.Password.Value)
	if err != nil {
		if errors.Is(err, services.ErrUnauthorized) {
			log.Warn().Str("username", lf.Username.Value).Msg("bad credentials")

			lf.Error = forms.ErrInvalidCredentials

			tmpl, err := templates.ExecuteLoginFormTmpl(&lf, w)
			if err != nil {
				log.Err(err).Msg("unable to generate login form template")
				return
			}

			w.WriteHeader(http.StatusUnauthorized)
			fmt.Fprint(w, tmpl)
			return
		}

		http.Error(w, "unexpected error occurred", http.StatusInternalServerError)
		return
	}

	cookie := session.GenerateCookie(a.IsSecure())
	http.SetCookie(w, cookie)

	tmpl, err := templates.ExecuteLoginSuccessTmpl(w)
	if err != nil {
		log.Err(err).Msg("unable to generate login success template")
		return
	}

	fmt.Fprint(w, tmpl)
}

func getLogin(w http.ResponseWriter, r *http.Request, a services.IAuthenticate) {
	if a.IsLogged(r) {
		tmpl, err := templates.ExecuteLoginSuccessTmpl(w)
		if err != nil {
			log.Err(err).Msg("unable to generate login success template")
			return
		}

		fmt.Fprint(w, tmpl)
		return
	}

	tmpl, err := templates.ExecuteLoginFormTmpl(&forms.LoginForm{}, w)
	if err != nil {
		log.Err(err).Msg("unable to generate login form template")
		return
	}

	fmt.Fprint(w, tmpl)
}