7 files changed, 149 insertions, 5 deletions
diff --git a/lib/git/git.go b/lib/git/git.go
index 71240221..02877281 100644
--- a/lib/git/git.go
+++ b/lib/git/git.go
@@ -1,6 +1,5 @@
-// SPDX-FileCopyrightText: 2018 M. Shulhan <ms@kilabit.info>
-//
 // SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2018 M. Shulhan <ms@kilabit.info>
 
 // Package git provide a wrapper for git command line interface.
 package git
@@ -13,6 +12,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
 
 	"git.sr.ht/~shulhan/pakakeh.go/lib/ini"
 )
@@ -28,6 +28,39 @@ var (
 	_stderr io.Writer = os.Stderr
 )
 
+// Git is a type for working with single git repository.
+type Git struct {
+	listIgnore map[string]*Gitignore
+
+	// absDir define the absolute path to the repository.
+	absDir string
+}
+
+// New start working on repository in directory `dir`.
+// If the `dir` does not contains ".git" directory it will return an error,
+// even if the parent directory may contains the ".git" directory.
+func New(dir string) (git *Git, err error) {
+	var logp = `New`
+	var fi os.FileInfo
+	var pathDotGit = filepath.Join(dir, `.git`)
+	fi, err = os.Stat(pathDotGit)
+	if err != nil {
+		return nil, fmt.Errorf(`%s: %q is not a git repository`, logp, dir)
+	}
+	if !fi.IsDir() {
+		return nil, fmt.Errorf(`%s: %q is not a git repository`, logp, dir)
+	}
+	dir, err = filepath.Abs(dir)
+	if err != nil {
+		return nil, fmt.Errorf(`%s: %w`, logp, err)
+	}
+	git = &Git{
+		absDir:     dir,
+		listIgnore: map[string]*Gitignore{},
+	}
+	return git, nil
+}
+
 // CheckoutRevision will set the HEAD to specific revision on specific branch.
 // Any untracked files and directories will be removed before checking out
 // existing branch or creating new branch.
@@ -188,6 +221,39 @@ func GetTag(repoDir, revision string) (tag string, err error) {
 	return tag, nil
 }
 
+// IsIgnored return true if the `path` is ignored by git.
+// This is processed by matching it with all of the patterns in the
+// ".gitignore" file inside the path directory and its parent, until the root
+// of Git repository.
+func (git *Git) IsIgnored(path string) (b bool) {
+	path = strings.TrimSpace(path)
+	if path == `` {
+		return true
+	}
+	// Traverse each directory from bottom to the top of git directory to
+	// load ".gitignore" file and match it with path.
+	var absPath = filepath.Join(git.absDir, path)
+	var dirGitignore = filepath.Dir(absPath)
+	var name = strings.TrimPrefix(absPath, dirGitignore)
+	name = strings.TrimLeft(name, `/`)
+	for strings.HasPrefix(dirGitignore, git.absDir) {
+		var ign *Gitignore
+		var ok bool
+		ign, ok = git.listIgnore[dirGitignore]
+		if !ok {
+			ign, _ = LoadGitignore(dirGitignore)
+			git.listIgnore[dirGitignore] = ign
+		}
+		if ign != nil && ign.IsIgnored(name) {
+			return true
+		}
+		dirGitignore = filepath.Dir(dirGitignore)
+		name = strings.TrimPrefix(absPath, dirGitignore)
+		name = strings.TrimLeft(name, `/`)
+	}
+	return false
+}
+
 // LatestCommit get the latest commit hash in short format from "ref".
 // If ref is empty, its default to "origin/master".
 func LatestCommit(repoDir, ref string) (commit string, err error) {
diff --git a/lib/git/git_example_test.go b/lib/git/git_example_test.go
new file mode 100644
index 00000000..0b55a251
--- /dev/null
+++ b/lib/git/git_example_test.go
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2025 M. Shulhan <ms@kilabit.info>
+
+package git_test
+
+import (
+	"fmt"
+	"log"
+
+	"git.sr.ht/~shulhan/pakakeh.go/lib/git"
+)
+
+func ExampleGit_IsIgnored() {
+	var agit *git.Git
+	var err error
+	agit, err = git.New(`testdata/IsIgnored`)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var listPath = []string{
+		``,
+		`vendor`,
+		`vendor/dummy`,
+		`hello.html`,
+		`hello.go`,
+		`foo/hello.go`,
+	}
+	var path string
+	var got bool
+	for _, path = range listPath {
+		got = agit.IsIgnored(path)
+		fmt.Printf("%q: %t\n", path, got)
+	}
+	// Output:
+	// "": true
+	// "vendor": true
+	// "vendor/dummy": true
+	// "hello.html": true
+	// "hello.go": false
+	// "foo/hello.go": false
+}
diff --git a/lib/git/git_test.go b/lib/git/git_test.go
index bcc63a95..70a9ccca 100644
--- a/lib/git/git_test.go
+++ b/lib/git/git_test.go
@@ -1,6 +1,5 @@
-// Copyright 2018, Shulhan <ms@kilabit.info>. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
+// SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2018 M. Shulhan <ms@kilabit.info>
 
 package git
 
@@ -44,6 +43,27 @@ func TestMain(m *testing.M) {
 	os.Exit(s)
 }
 
+func TestNew(t *testing.T) {
+	type testCase struct {
+		dir      string
+		expError string
+	}
+	var listCase = []testCase{{
+		dir:      `testdata/New/fail_no_git`,
+		expError: `New: "testdata/New/fail_no_git" is not a git repository`,
+	}, {
+		dir:      `testdata/New/fail_not_dir`,
+		expError: `New: "testdata/New/fail_not_dir" is not a git repository`,
+	}}
+
+	var err error
+	var tcase testCase
+	for _, tcase = range listCase {
+		_, err = New(tcase.dir)
+		test.Assert(t, `error`, tcase.expError, err.Error())
+	}
+}
+
 func TestClone(t *testing.T) {
 	cases := []struct {
 		desc, dest, expErr, expStderr, expStdout string
diff --git a/lib/git/testdata/IsIgnored/.gitignore b/lib/git/testdata/IsIgnored/.gitignore
new file mode 100644
index 00000000..15989de8
--- /dev/null
+++ b/lib/git/testdata/IsIgnored/.gitignore
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# SPDX-FileCopyrightText: 2025 M. Shulhan <ms@kilabit.info>
+
+# comment
+  # comment
+  vendor/  # ignore vendor directory, but not vendor file.
+/hello.*    # ignore hello at root, but not foo/hello.go.
+!hello.go
diff --git a/lib/git/testdata/IsIgnored/foo/hello.go b/lib/git/testdata/IsIgnored/foo/hello.go
new file mode 100644
index 00000000..b61e7105
--- /dev/null
+++ b/lib/git/testdata/IsIgnored/foo/hello.go
@@ -0,0 +1,4 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2025 M. Shulhan <ms@kilabit.info>
+
+package foo
diff --git a/lib/git/testdata/IsIgnored/vendor/empty b/lib/git/testdata/IsIgnored/vendor/empty
new file mode 100644
index 00000000..62f13a9e
--- /dev/null
+++ b/lib/git/testdata/IsIgnored/vendor/empty
@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2025 M. Shulhan <ms@kilabit.info>
diff --git a/lib/git/testdata/New/fail_no_git/.gitignore b/lib/git/testdata/New/fail_no_git/.gitignore
new file mode 100644
index 00000000..62f13a9e
--- /dev/null
+++ b/lib/git/testdata/New/fail_no_git/.gitignore
@@ -0,0 +1,2 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// SPDX-FileCopyrightText: 2025 M. Shulhan <ms@kilabit.info>