/*
 * Copyright 2021 CloudWeGo Authors
 *
 * 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 (
	"time"

	"github.com/cloudwego/kitex/pkg/rpcinfo"
	"github.com/cloudwego/kitex/pkg/stats"
)

// CalculateEventCost get events from rpcstats, and calculates the time duration of (end - start).
// It returns 0 when get nil rpcinfo event of either stats event.
func CalculateEventCost(rpcstats rpcinfo.RPCStats, start, end stats.Event) time.Duration {
	endEvent := rpcstats.GetEvent(end)
	startEvent := rpcstats.GetEvent(start)
	if startEvent == nil || endEvent == nil {
		return 0
	}
	return endEvent.Time().Sub(startEvent.Time())
}
