/*
 * Copyright 2016, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

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
}
