// Copyright © 2016 Jip J. Dekker <jip@dekker.li>
//
// 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 helpers

import (
	"errors"
	"io"
	"os"
	"path/filepath"
	"time"

	log "github.com/Sirupsen/logrus"
)

// CleanPath returns a cleaned path from a given string relative
// to the working directory unless explicitly absolute
func CleanPath(path string) (string, error) {
	if path == "" {
		// No given path, use working directory
		return os.Getwd()
	} else if filepath.IsAbs(path) {
		// Given path is absolute
		return filepath.Clean(path), nil
	} else {
		// Given path is a relative path
		dir, err := os.Getwd()
		if err == nil {
			return filepath.Join(dir, path), nil
		}
		return "", err
	}
}

// Exists checks if a file or directory exists.
func Exists(path string) bool {
	_, err := os.Stat(path)
	if err == nil {
		return true
	}
	if !os.IsNotExist(err) {
		log.WithFields(log.Fields{"error": err, "path": path}).
			Panic("Unable to check path")
	}
	return false
}

// ExistsOrCreate will create a directory unless it already Exists
func ExistsOrCreate(path string) (err error) {
	if !Exists(path) {
		log.WithFields(log.Fields{"path": path}).Info("creating directory")
		err = os.MkdirAll(path, os.ModePerm)
	}
	return
}

// LastModified returns the time the file on the path was last modified,
// if file lookup fails the current time is returned.
func LastModified(path string) time.Time {
	stat, err := os.Stat(path)
	if err == nil {
		return stat.ModTime()
	}
	return time.Now()
}

// FindFileDir returns the path of the
func FindFileDir(file string) (string, error) {
	wd, err := os.Getwd()
	if err != nil {
		return "", nil
	}
	for path := wd; path != "/"; path = filepath.Dir(path) {
		if Exists(filepath.Join(path, file)) {
			return path, nil
		}
	}
	return "", &os.PathError{
		Path: wd,
		Err:  errors.New("directory containing " + file + " not found"),
	}
}

// AbsolutePath returns an the path if it is absolute or
// otherwise filepath.Join(root, path)
func AbsolutePath(path, root string) string {
	if filepath.IsAbs(path) {
		return path
	}
	return filepath.Join(root, path)
}

// CleanFile removes the file on the given path if it exists. In case of
// failure, an error will be logged.
func CleanFile(path string) {
	if Exists(path) {
		if err := os.Remove(path); err != nil {
			log.WithFields(log.Fields{
				"error": err,
				"file":  path,
			}).Error("unable to delete file")
		}
	}
}

func EmptyDir(name string) (bool, error) {
	f, err := os.Open(name)
	if err != nil {
		return false, err
	}
	defer f.Close()

	_, err = f.Readdirnames(1) // Or f.Readdir(1)
	if err == io.EOF {
		return true, nil
	}
	return false, err // Either not empty or error, suits both cases
}