/*
 * Copyright 2017-2019 Kopano and its licensors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package utils

import (
	"net/http"
	"net/url"
)

// OriginFromRequestHeaders tries to find information about the origin from the
// provided http.Header. It first looks into the Origin header field and if that
// is not found it looks into the Referer header field. If both are not found
// an empty string is returned.
func OriginFromRequestHeaders(header http.Header) string {
	origin := header.Get("Origin")
	if origin == "" {
		referer := header.Get("Referer")
		if referer != "" {
			refererURI, _ := url.Parse(referer)
			origin = refererURI.Scheme + "://" + refererURI.Host
		}
	}

	return origin
}