package handlers

import (
	"context"
	"fmt"
	"html/template"
	"net/http"
	"net/url"

	"github.com/lestrrat-go/jwx/jwk"
	"github.com/nicksnyder/go-i18n/v2/i18n"

	"git.cacert.org/oidc_login/app/services"
	commonServices "git.cacert.org/oidc_login/common/services"
)

type indexHandler struct {
	bundle         *i18n.Bundle
	indexTemplate  *template.Template
	keySet         *jwk.Set
	logoutUrl      string
	messageCatalog *commonServices.MessageCatalog
	serverAddr     string
}

func (h *indexHandler) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
	if request.Method != http.MethodGet {
		http.Error(writer, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
		return
	}
	if request.URL.Path != "/" {
		http.NotFound(writer, request)
		return
	}
	accept := request.Header.Get("Accept-Language")
	localizer := i18n.NewLocalizer(h.bundle, accept)
	writer.WriteHeader(http.StatusOK)

	session, err := services.GetSessionStore().Get(request, sessionName)
	if err != nil {
		http.Error(writer, err.Error(), http.StatusInternalServerError)
		return
	}

	logoutUrl, err := url.Parse(h.logoutUrl)
	if err != nil {
		http.Error(writer, err.Error(), http.StatusInternalServerError)
		return
	}
	var idToken string
	var ok bool
	if idToken, ok = session.Values[sessionKeyIdToken].(string); ok {
		logoutUrl.RawQuery = url.Values{
			"id_token_hint":            []string{idToken},
			"post_logout_redirect_uri": []string{fmt.Sprintf("https://%s/after-logout", h.serverAddr)},
		}.Encode()
	} else {
		return
	}

	oidcToken, err := ParseIdToken(idToken, h.keySet)
	if err != nil {
		http.Error(writer, err.Error(), http.StatusInternalServerError)
		return
	}

	writer.Header().Add("Content-Type", "text/html")
	err = h.indexTemplate.Lookup("base").Execute(writer, map[string]interface{}{
		"Title": h.messageCatalog.LookupMessage("IndexTitle", nil, localizer),
		"Greeting": h.messageCatalog.LookupMessage("IndexGreeting", map[string]interface{}{
			"User": oidcToken.Name(),
		}, localizer),
		"IntroductionText": h.messageCatalog.LookupMessage("IndexIntroductionText", nil, localizer),
		"LogoutLabel":      h.messageCatalog.LookupMessage("LogoutLabel", nil, localizer),
		"LogoutURL":        logoutUrl.String(),
	})
	if err != nil {
		http.Error(writer, err.Error(), http.StatusInternalServerError)
		return
	}
}

func NewIndexHandler(ctx context.Context, serverAddr string) (*indexHandler, error) {
	indexTemplate, err := template.ParseFiles(
		"templates/app/base.gohtml", "templates/app/index.gohtml")
	if err != nil {
		return nil, err
	}
	return &indexHandler{
		bundle:         commonServices.GetI18nBundle(ctx),
		indexTemplate:  indexTemplate,
		keySet:         commonServices.GetJwkSet(ctx),
		logoutUrl:      commonServices.GetOidcConfig(ctx).EndSessionEndpoint,
		messageCatalog: commonServices.GetMessageCatalog(ctx),
		serverAddr:     serverAddr,
	}, nil
}