package smb2

import (
	"errors"
	"os"
	"regexp"
	"strings"
)

var NORMALIZE_PATH = true // normalize path arguments automatically

const PathSeparator = '\\'

func IsPathSeparator(c uint8) bool {
	return c == '\\'
}

func base(path string) string {
	j := len(path)
	for j > 0 && IsPathSeparator(path[j-1]) {
		j--
	}

	if j == 0 {
		return ""
	}

	i := j - 1
	for i > 0 && !IsPathSeparator(path[i-1]) {
		i--
	}

	return path[i:j]
}

func dir(path string) string {
	if path == "" {
		return ""
	}

	i := len(path)
	for i > 0 && IsPathSeparator(path[i-1]) {
		i--
	}

	if i == 0 {
		return "\\"
	}

	i--
	for i > 0 && !IsPathSeparator(path[i-1]) {
		i--
	}

	if i == 0 {
		return ""
	}

	i--
	for i > 0 && IsPathSeparator(path[i-1]) {
		i--
	}

	if i == 0 {
		return "\\"
	}

	return path[:i]
}

func validatePath(op string, path string, allowAbs bool) error {
	if len(path) == 0 {
		return nil
	}

	if !NORMALIZE_PATH {
		if strings.ContainsRune(path, '/') {
			return &os.PathError{Op: op, Path: path, Err: errors.New("can't use '/' as a path separator; use '\\' instead")}
		}
	}

	if !allowAbs && path[0] == '\\' {
		return &os.PathError{Op: op, Path: path, Err: errors.New("leading '\\' is not allowed in this operation")}
	}

	return nil
}

var mountPathPattern = regexp.MustCompile(`^\\\\[^\\/]+\\[^\\/]+$`)

func validateMountPath(path string) error {
	if !mountPathPattern.MatchString(path) {
		return &os.PathError{Op: "mount", Path: path, Err: errors.New(`mount path must be a valid share name (\\<server>\<share>)`)}
	}
	return nil
}

func normPath(path string) string {
	if !NORMALIZE_PATH {
		return path
	}
	path = strings.Replace(path, `/`, `\`, -1)
	for strings.HasPrefix(path, `.\`) {
		path = path[2:]
	}
	if path == "." {
		return ""
	}
	return path
}

func normPattern(pattern string) string {
	if !NORMALIZE_PATH {
		return pattern
	}
	pattern = strings.Replace(pattern, `/`, `\`, -1)
	for strings.HasPrefix(pattern, `.\`) {
		pattern = pattern[2:]
	}
	return pattern
}

func join(elem ...string) string {
	return normPath(strings.Join(elem, string(PathSeparator)))
}

func split(path string) (dir, file string) {
	i := len(path) - 1
	for i >= 0 && !IsPathSeparator(path[i]) {
		i--
	}
	return path[:i+1], path[i+1:]
}