package http

import (
	"html/template"
	"net/http"
	"time"

	_ "embed"

	"forge.cadoles.com/arcad/edge/pkg/module/auth"
	"forge.cadoles.com/arcad/edge/pkg/module/auth/http/passwd"
	"github.com/go-chi/chi/v5"
	"github.com/lestrrat-go/jwx/v2/jwa"
	"github.com/lestrrat-go/jwx/v2/jwk"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

//go:embed templates/login.html.tmpl
var rawLoginTemplate string
var loginTemplate *template.Template

var (
	errNotFound        = errors.New("not found")
	errInvalidPassword = errors.New("invalid password")
)

func init() {
	loginTemplate = template.Must(template.New("").Parse(rawLoginTemplate))
}

type LocalHandler struct {
	router   chi.Router
	algo     jwa.KeyAlgorithm
	key      jwk.Key
	accounts map[string]LocalAccount
}

func (h *LocalHandler) initRouter(prefix string) {
	router := chi.NewRouter()

	router.Route(prefix, func(r chi.Router) {
		r.Get("/login", h.serveForm)
		r.Post("/login", h.handleForm)
		r.Get("/logout", h.handleLogout)
	})

	h.router = router
}

type loginTemplateData struct {
	URL      string
	Username string
	Password string
	Message  string
}

func (h *LocalHandler) serveForm(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	data := loginTemplateData{
		URL:      r.URL.String(),
		Username: "",
		Password: "",
		Message:  "",
	}

	if err := loginTemplate.Execute(w, data); err != nil {
		logger.Error(ctx, "could not execute login page template", logger.E(errors.WithStack(err)))
	}
}

func (h *LocalHandler) handleForm(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	if err := r.ParseForm(); err != nil {
		logger.Error(ctx, "could not parse form", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)

		return
	}

	username := r.Form.Get("username")
	password := r.Form.Get("password")

	data := loginTemplateData{
		URL:      r.URL.String(),
		Username: username,
		Password: password,
		Message:  "",
	}

	account, err := h.authenticate(username, password)
	if err != nil {
		if errors.Is(err, errNotFound) || errors.Is(err, errInvalidPassword) {
			data.Message = "Invalid username or password."

			if err := loginTemplate.Execute(w, data); err != nil {
				logger.Error(ctx, "could not execute login page template", logger.E(errors.WithStack(err)))
			}

			return
		}

		logger.Error(ctx, "could not authenticate account", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	token, err := generateSignedToken(h.algo, h.key, account.Claims)
	if err != nil {
		logger.Error(ctx, "could not generate signed token", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	cookie := http.Cookie{
		Name:     auth.CookieName,
		Value:    string(token),
		HttpOnly: false,
		Path:     "/",
	}

	http.SetCookie(w, &cookie)

	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func (h *LocalHandler) handleLogout(w http.ResponseWriter, r *http.Request) {
	http.SetCookie(w, &http.Cookie{
		Name:     auth.CookieName,
		Value:    "",
		HttpOnly: false,
		Expires:  time.Unix(0, 0),
		Path:     "/",
	})

	http.Redirect(w, r, "/", http.StatusSeeOther)
}

func (h *LocalHandler) authenticate(username, password string) (*LocalAccount, error) {
	account, exists := h.accounts[username]
	if !exists {
		return nil, errors.WithStack(errNotFound)
	}

	matches, err := passwd.Match(account.Algo, password, account.Password)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if !matches {
		return nil, errors.WithStack(errInvalidPassword)
	}

	return &account, nil
}

func NewLocalHandler(algo jwa.KeyAlgorithm, key jwk.Key, funcs ...LocalHandlerOptionFunc) *LocalHandler {
	opts := defaultLocalHandlerOptions()
	for _, fn := range funcs {
		fn(opts)
	}

	handler := &LocalHandler{
		algo:     algo,
		key:      key,
		accounts: toAccountsMap(opts.Accounts),
	}

	handler.initRouter(opts.RoutePrefix)

	return handler
}

// ServeHTTP implements http.Handler.
func (h *LocalHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	h.router.ServeHTTP(w, r)
}

var _ http.Handler = &LocalHandler{}