// package fileutils provides utililty methods to copy and move files and directories.
package fileutils

import (
	"fmt"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
)

const debugCopypath = false
const debugCopyfile = false

// Copypath copies the contents of src to dst, excluding any file or
// directory that starts with a period.
func Copypath(dst string, src string) error {
	err := filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		if strings.HasPrefix(filepath.Base(path), ".") {
			if info.IsDir() {
				return filepath.SkipDir
			}
			return nil
		}

		if info.IsDir() {
			return nil
		}

		dst := filepath.Join(dst, path[len(src):])

		if info.Mode()&os.ModeSymlink != 0 {
			return Copylink(dst, path)
		}

		return Copyfile(dst, path)
	})
	if err != nil {
		// if there was an error during copying, remove the partial copy.
		RemoveAll(dst)
	}
	return err
}

func Copyfile(dst, src string) error {
	err := mkdir(filepath.Dir(dst))
	if err != nil {
		return fmt.Errorf("copyfile: mkdirall: %v", err)
	}
	r, err := os.Open(src)
	if err != nil {
		return fmt.Errorf("copyfile: open(%q): %v", src, err)
	}
	defer r.Close()
	w, err := os.Create(dst)
	if err != nil {
		return fmt.Errorf("copyfile: create(%q): %v", dst, err)
	}
	defer w.Close()
	if debugCopyfile {
		fmt.Printf("copyfile(dst: %v, src: %v)\n", dst, src)
	}
	_, err = io.Copy(w, r)
	return err
}

func Copylink(dst, src string) error {
	target, err := os.Readlink(src)
	if err != nil {
		return fmt.Errorf("copylink: readlink: %v", err)
	}
	if err := mkdir(filepath.Dir(dst)); err != nil {
		return fmt.Errorf("copylink: mkdirall: %v", err)
	}
	if err := os.Symlink(target, dst); err != nil {
		return fmt.Errorf("copylink: symlink: %v", err)
	}
	if debugCopyfile {
		fmt.Printf("copylink(dst: %v, src: %v, tgt: %s)\n", dst, src, target)
	}
	return nil
}

// RemoveAll removes path and any children it contains. Unlike os.RemoveAll it
// deletes read only files on Windows.
func RemoveAll(path string) error {
	if runtime.GOOS == "windows" {
		// Simple case: if Remove works, we're done.
		err := os.Remove(path)
		if err == nil || os.IsNotExist(err) {
			return nil
		}
		// make sure all files are writable so we can delete them
		filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
			if err != nil {
				// walk gave us some error, give it back.
				return err
			}
			mode := info.Mode()
			if mode|0200 == mode {
				return nil
			}
			return os.Chmod(path, mode|0200)
		})
	}
	return os.RemoveAll(path)
}

func mkdir(path string) error {
	return os.MkdirAll(path, 0755)
}