// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library 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 Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package common

import (
	"bytes"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

// FileExist checks if a file exists at filePath.
func FileExist(filePath string) bool {
	_, err := os.Stat(filePath)
	if err != nil && os.IsNotExist(err) {
		return false
	}
	return true
}

// AbsolutePath returns datadir + filename, or filename if it is absolute.
func AbsolutePath(datadir string, filename string) string {
	if filepath.IsAbs(filename) {
		return filename
	}
	return filepath.Join(datadir, filename)
}

func GetGoRoot() (string, error) {
	cmd := exec.Command("go", "env", "GOROOT")
	var out bytes.Buffer
	cmd.Stdout = &out
	err := cmd.Run()
	if err != nil {
		return "", err
	}
	return strings.TrimSpace(out.String()), nil
}
