// Vikunja is a to-do list application to facilitate your life.
// Copyright 2018-present Vikunja and contributors. All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package mail

import (
	"net/url"
	"os"

	"code.vikunja.io/api/pkg/config"
	"code.vikunja.io/api/pkg/log"
)

// GetMailDomain returns the hostname from the configured public URL,
// or "vikunja" as a fallback. Used for RFC 5322 compliant Message-ID
// and thread ID generation.
func GetMailDomain() string {
	publicURL := config.ServicePublicURL.GetString()
	if publicURL != "" {
		if parsedURL, err := url.Parse(publicURL); err == nil && parsedURL.Hostname() != "" {
			return parsedURL.Hostname()
		}
	}
	if hostname, err := os.Hostname(); err == nil && hostname != "" {
		if log.IsInitialized() {
			log.Warningf("Could not determine mail domain from public URL, falling back to hostname %q", hostname)
		}
		return hostname
	}
	if log.IsInitialized() {
		log.Warningf("Could not determine mail domain from public URL or hostname, falling back to %q", "vikunja")
	}
	return "vikunja"
}