package middleware

import (
	"fmt"
	"net/http"
	"strings"

	"me-fit/service"
)

type csrfResponseWriter struct {
	http.ResponseWriter
	auth    service.Auth
	session *service.Session
}

func newCsrfResponseWriter(w http.ResponseWriter, auth service.Auth, session *service.Session) *csrfResponseWriter {
	return &csrfResponseWriter{
		ResponseWriter: w,
		auth:           auth,
		session:        session,
	}
}

func (rr *csrfResponseWriter) Write(data []byte) (int, error) {
	dataStr := string(data)
	if strings.Contains(dataStr, "</form>") {
		csrfToken, err := rr.auth.GetCsrfToken(rr.session)
		if err == nil {
			csrfField := fmt.Sprintf(`<input type="hidden" name="csrf-token" value="%s">`, csrfToken)
			dataStr = strings.ReplaceAll(dataStr, "</form>", csrfField+"</form>")
			dataStr = strings.ReplaceAll(dataStr, "CSRF_TOKEN", csrfToken)
		}
	}

	return rr.ResponseWriter.Write([]byte(dataStr))
}

func (rr *csrfResponseWriter) WriteHeader(statusCode int) {
	rr.ResponseWriter.WriteHeader(statusCode)
}

func CrossSiteRequestForgery(auth service.Auth) func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

			session := GetSession(r)

			if r.Method == http.MethodPost ||
				r.Method == http.MethodPut ||
				r.Method == http.MethodDelete ||
				r.Method == http.MethodPatch {

				csrfToken := r.FormValue("csrf-token")
				if csrfToken == "" {
					csrfToken = r.Header.Get("csrf-token")
				}
				if csrfToken == "" || !auth.IsCsrfTokenValid(csrfToken, session.Id) {
					http.Error(w, "", http.StatusForbidden)
					return
				}
			}

			// Always sign in anonymous
			// This way, there is no way to forget creating a csrf token
			if session == nil {
				session, _ = auth.SignInAnonymous()

				cookie := CreateSessionCookie(session.Id)
				http.SetCookie(w, &cookie)
			}

			responseWriter := newCsrfResponseWriter(w, auth, session)
			next.ServeHTTP(responseWriter, r)
		})
	}
}