/*
 *
 * Copyright 2016 gRPC 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 main

import (
	"log"
	"os"
	"path/filepath"
	"syscall"
)

// abs returns the absolute path the given relative file or directory path,
// relative to the google.golang.org/grpc directory in the user's GOPATH.
// If rel is already absolute, it is returned unmodified.
func abs(rel string) string {
	if filepath.IsAbs(rel) {
		return rel
	}
	v, err := goPackagePath("google.golang.org/grpc")
	if err != nil {
		log.Fatalf("Error finding google.golang.org/grpc/testdata directory: %v", err)
	}
	return filepath.Join(v, rel)
}

func cpuTimeDiff(first *syscall.Rusage, latest *syscall.Rusage) (float64, float64) {
	var (
		utimeDiffs  = latest.Utime.Sec - first.Utime.Sec
		utimeDiffus = latest.Utime.Usec - first.Utime.Usec
		stimeDiffs  = latest.Stime.Sec - first.Stime.Sec
		stimeDiffus = latest.Stime.Usec - first.Stime.Usec
	)

	uTimeElapsed := float64(utimeDiffs) + float64(utimeDiffus)*1.0e-6
	sTimeElapsed := float64(stimeDiffs) + float64(stimeDiffus)*1.0e-6

	return uTimeElapsed, sTimeElapsed
}

func goPackagePath(pkg string) (path string, err error) {
	gp := os.Getenv("GOPATH")
	if gp == "" {
		return path, os.ErrNotExist
	}
	for _, p := range filepath.SplitList(gp) {
		dir := filepath.Join(p, "src", filepath.FromSlash(pkg))
		fi, err := os.Stat(dir)
		if os.IsNotExist(err) {
			continue
		}
		if err != nil {
			return "", err
		}
		if !fi.IsDir() {
			continue
		}
		return dir, nil
	}
	return path, os.ErrNotExist
}