package helpers

import (
	"os"
	"path/filepath"
	"strconv"
	"strings"
)

func SafeFilename(name string) (string, bool) {
	filename := filepath.Base(name)
	filename = strings.TrimSpace(filename)
	return filename, filename != "" && filename != "." && filename != string(filepath.Separator)
}

func SafeChildPath(parent string, filename string) (string, bool) {
	parent = filepath.Clean(parent)
	filename = strings.TrimSpace(filename)
	if parent == "" || filename == "" || filepath.IsAbs(filename) {
		return "", false
	}

	path := filepath.Clean(filepath.Join(parent, filename))
	relative, err := filepath.Rel(parent, path)
	if err != nil || relative == "." || strings.HasPrefix(relative, ".."+string(filepath.Separator)) || relative == ".." {
		return "", false
	}

	return path, true
}

func UniqueFilename(directory string, filename string) string {
	if _, err := os.Stat(filepath.Join(directory, filename)); os.IsNotExist(err) {
		return filename
	}

	extension := filepath.Ext(filename)
	base := strings.TrimSuffix(filename, extension)
	for count := 2; ; count++ {
		candidate := base + "-" + strconv.Itoa(count) + extension
		if _, err := os.Stat(filepath.Join(directory, candidate)); os.IsNotExist(err) {
			return candidate
		}
	}
}

func UniqueNameInBatch(filename string, usedNames map[string]int) string {
	count := usedNames[filename]
	usedNames[filename] = count + 1

	if count == 0 {
		return filename
	}

	extension := filepath.Ext(filename)
	base := strings.TrimSuffix(filename, extension)
	return base + "-" + strconv.Itoa(count+1) + extension
}