// Package gorecurcopy provides recursive copying in Go (golang) with a
// minimum of extra packages. Original concept by Oleg Neumyvakin
// (https://stackoverflow.com/users/1592008/oleg-neumyvakin) and modified
// by Dirk Avery.
// Slightly modified by me.
package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path/filepath"
	// "syscall"
)

// copyDir recursively copies a src directory to a destination.
func copyDir(src, dst string) error {
	entries, err := ioutil.ReadDir(src)
	if err != nil {
		return err
	}
	for _, entry := range entries {
		sourcePath := filepath.Join(src, entry.Name())
		destPath := filepath.Join(dst, entry.Name())

		fileInfo, err := os.Lstat(sourcePath)
		if err != nil {
			return err
		}

		switch fileInfo.Mode() & os.ModeType {
		case os.ModeDir:
			if err := _createDir(destPath, 0755); err != nil {
				return err
			}
			if err := copyDir(sourcePath, destPath); err != nil {
				return err
			}
		case os.ModeSymlink:
			if err := copySymlink(sourcePath, destPath); err != nil {
				return err
			}
		default:
			if err := _copy(sourcePath, destPath); err != nil {
				return err
			}
		}

		/*
			stat, ok := fileInfo.Sys().(*syscall.Stat_t)
			if !ok {
				return fmt.Errorf("failed to get raw syscall.Stat_t data for '%s'", sourcePath)
			}
			if err := os.Lchown(destPath, int(stat.Uid), int(stat.Gid)); err != nil {
				return err
			}
		*/

		isSymlink := entry.Mode()&os.ModeSymlink != 0
		if !isSymlink {
			if err := os.Chmod(destPath, entry.Mode()); err != nil {
				return err
			}
		}
	}
	return nil
}

// Copy copies a src file to a dst file where src and dst are regular files.
func _copy(src, dst string) error {
	sourceFileStat, err := os.Stat(src)
	if err != nil {
		return err
	}

	if !sourceFileStat.Mode().IsRegular() {
		return fmt.Errorf("%s is not a regular file", src)
	}

	source, err := os.Open(src)
	if err != nil {
		return err
	}
	defer source.Close()

	destination, err := os.Create(dst)
	if err != nil {
		return err
	}
	defer destination.Close()
	_, err = io.Copy(destination, source)
	return err
}

func _exists(path string) bool {
	if _, err := os.Stat(path); os.IsNotExist(err) {
		return false
	}

	return true
}

func _createDir(dir string, perm os.FileMode) error {
	if _exists(dir) {
		return nil
	}

	if err := os.MkdirAll(dir, perm); err != nil {
		return fmt.Errorf("failed to create directory: '%s', error: '%s'", dir, err.Error())
	}

	return nil
}

// copySymlink copies a symbolic link from src to dst.
func copySymlink(src, dst string) error {
	link, err := os.Readlink(src)
	if err != nil {
		return err
	}
	return os.Symlink(link, dst)
}