package dirlist

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

const keep = 64<<10 - 100

func List(path string) (string, error) {
	entries, err := os.ReadDir(path)
	if err != nil {
		return "", err
	}
	if len(entries) == 0 {
		return fmt.Sprintf("%s is empty.\n", path), nil
	}
	b := &strings.Builder{}
	for i, e := range entries {
		name := e.Name()
		info, err := os.Stat(filepath.Join(path, name))
		if err == nil && info.IsDir() {
			name += "/"
		}
		if b.Len()+len(name)+1 > keep {
			fmt.Fprintf(b, "(%d more entries not shown; output stops at 64 KiB)\n", len(entries)-i)
			break
		}
		b.WriteString(name + "\n")
	}
	return b.String(), nil
}