@@ -0,0 +1,122 @@
+package ignore
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+
+	ignore "github.com/sabhiram/go-gitignore"
+
+	"alin.ovh/erl/repository"
+)
+
+var DefaultIgnoreFilename = ".ignore"
+
+type Filter struct {
+	repo        *repository.Repo
+	projectRoot string
+	wd          string
+
+	givenPaths []string
+	paths      []string
+	ignores    []*Ignore
+}
+
+type Ignore struct {
+	*ignore.GitIgnore
+
+	filename string
+}
+
+func New(wd string, path ...string) *Filter {
+	return &Filter{
+		wd:         wd,
+		givenPaths: path,
+	}
+}
+
+func (f *Filter) ReadIgnoreFiles(ctx context.Context) error {
+	if f.projectRoot == "" {
+		repo, err := repository.GetRepo(ctx, f.wd)
+		if err != nil {
+			return err
+		}
+
+		f.repo = repo
+		f.projectRoot = repo.GetRoot()
+	}
+
+	err := f.getPaths()
+	if err != nil {
+		return err
+	}
+
+	f.ignores = []*Ignore{}
+	for _, path := range f.paths {
+		ig, err := ignore.CompileIgnoreFile(path)
+		if err != nil {
+			return err
+		}
+
+		f.ignores = append(f.ignores, &Ignore{
+			GitIgnore: ig,
+			filename:  path,
+		})
+	}
+
+	return nil
+}
+
+func (f *Filter) Ignored(path string) bool {
+	return slices.ContainsFunc(f.ignores, func(ig *Ignore) bool {
+		return ig.MatchesPath(path)
+	})
+}
+
+func (f *Filter) getPaths() error {
+	f.paths = f.givenPaths
+
+	rel, err := filepath.Rel(f.projectRoot, f.wd)
+	if err != nil {
+		return err
+	}
+
+	ignoreFileNames := []string{DefaultIgnoreFilename}
+	ignoreFileNames = append(ignoreFileNames, f.repo.GetIgnoreFileNames()...)
+	dirs := strings.Split(rel, string(filepath.Separator))
+	for i := range dirs {
+		var dir string
+		if i == 0 {
+			dir = "."
+		} else {
+			dir = filepath.Join(dirs[:i+1]...)
+		}
+
+		for _, basename := range ignoreFileNames {
+			filename := filepath.Join(f.projectRoot, dir, basename)
+			stat, err := os.Stat(filename)
+			if err != nil {
+				if errors.Is(err, os.ErrNotExist) {
+					continue
+				}
+
+				return err
+			}
+			if stat.IsDir() {
+				return fmt.Errorf(
+					"%s path is a directory: %s",
+					basename,
+					filepath.Join(f.projectRoot, dir, filename),
+				)
+			}
+
+			f.paths = append(f.paths, filename)
+		}
+	}
+
+	return nil
+}