finished, also added cobra cli

internal/filter/filter.go

@@ -0,0 +1,60 @@
+package filter
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type Filter struct {
+	MaxSize    int64
+	Extensions []string
+	Ignores    []string
+}
+
+func (f *Filter) ShouldSkipDir(name string) bool {
+	if strings.HasPrefix(name, ".") {
+		return true
+	}
+	for _, pattern := range f.Ignores {
+		matched, _ := filepath.Match(pattern, name)
+		if matched {
+			return true
+		}
+	}
+	return false
+}
+
+func (f *Filter) ShouldSkipFile(path, name string, info os.FileInfo) bool {
+	if strings.HasPrefix(name, ".") {
+		return true
+	}
+
+	for _, pattern := range f.Ignores {
+		matched, _ := filepath.Match(pattern, name)
+		if matched {
+			return true
+		}
+	}
+
+	ext := filepath.Ext(path)
+	for _, bad := range f.Extensions {
+		if strings.EqualFold(ext, bad) {
+			return true
+		}
+	}
+
+	if info.Size() > f.MaxSize {
+		return true
+	}
+
+	return false
+}
+
+func IsSymlink(path string) bool {
+	info, err := os.Lstat(path)
+	if err != nil {
+		return false
+	}
+	return info.Mode()&os.ModeSymlink != 0
+}