From b0f6f15a9e371469697206281f02c9352ac41550 Mon Sep 17 00:00:00 2001
From: Alexandre Pujol <alexandre@pujol.io>
Date: Wed, 19 Jun 2024 23:55:45 +0100
Subject: [PATCH] refractor: use internal Intersect function.

---
 pkg/aa/rules.go        |  6 +++---
 pkg/util/tools.go      | 19 +++++++++++++++++
 pkg/util/tools_test.go | 47 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/pkg/aa/rules.go b/pkg/aa/rules.go
index f292ee553..409b48618 100644
--- a/pkg/aa/rules.go
+++ b/pkg/aa/rules.go
@@ -8,7 +8,7 @@ import (
 	"slices"
 	"strings"
 
-	"github.com/samber/lo"
+	"github.com/roddhjav/apparmor.d/pkg/util"
 )
 
 type requirement map[string][]string
@@ -225,7 +225,7 @@ func (r Rules) Format() Rules {
 			rule := r[i].(*File)
 
 			// Add padding to align with other transition rule
-			isTransition := lo.Intersect(transitions, rule.Access)
+			isTransition := util.Intersect(transitions, rule.Access)
 			if len(isTransition) > 0 {
 				ruleLen := len(rule.Path) + 1
 				paddingMaxLenght = max(ruleLen, paddingMaxLenght)
@@ -265,7 +265,7 @@ func (r Rules) Format() Rules {
 			}
 
 			// Do not add new line on executable rule
-			isTransition := lo.Intersect(transitions, rule.Access)
+			isTransition := util.Intersect(transitions, rule.Access)
 			if len(isTransition) > 0 {
 				continue
 			}
diff --git a/pkg/util/tools.go b/pkg/util/tools.go
index 96cffb36a..30d5251d6 100644
--- a/pkg/util/tools.go
+++ b/pkg/util/tools.go
@@ -82,6 +82,25 @@ func RemoveDuplicate[T comparable](inlist []T) []T {
 	return list
 }
 
+// Intersect returns the intersection between two collections.
+// From https://github.com/samber/lo
+func Intersect[T comparable](list1 []T, list2 []T) []T {
+	result := []T{}
+	seen := map[T]struct{}{}
+
+	for _, elem := range list1 {
+		seen[elem] = struct{}{}
+	}
+
+	for _, elem := range list2 {
+		if _, ok := seen[elem]; ok {
+			result = append(result, elem)
+		}
+	}
+
+	return result
+}
+
 // CopyTo recursivelly copy all files from a source path to a destination path.
 func CopyTo(src *paths.Path, dst *paths.Path) error {
 	files, err := src.ReadDirRecursiveFiltered(nil,
diff --git a/pkg/util/tools_test.go b/pkg/util/tools_test.go
index b6f85a386..4d5cade6a 100644
--- a/pkg/util/tools_test.go
+++ b/pkg/util/tools_test.go
@@ -59,6 +59,53 @@ func TestRemoveDuplicate(t *testing.T) {
 	}
 }
 
+func TestIntersect(t *testing.T) {
+	tests := []struct {
+		name  string
+		list1 []int
+		list2 []int
+		want  []int
+	}{
+		{
+			name:  "1",
+			list1: []int{0, 1, 2, 3, 4, 5},
+			list2: []int{0, 2},
+			want:  []int{0, 2},
+		},
+		{
+			name:  "2",
+			list1: []int{0, 1, 2, 3, 4, 5},
+			list2: []int{0, 6},
+			want:  []int{0},
+		},
+		{
+			name:  "3",
+			list1: []int{0, 1, 2, 3, 4, 5},
+			list2: []int{-1, 6},
+			want:  []int{},
+		},
+		{
+			name:  "4",
+			list1: []int{0, 6},
+			list2: []int{0, 1, 2, 3, 4, 5},
+			want:  []int{0},
+		},
+		{
+			name:  "5",
+			list1: []int{0, 6, 0},
+			list2: []int{0, 1, 2, 3, 4, 5},
+			want:  []int{0},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := Intersect(tt.list1, tt.list2); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Intersect() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
 func TestToRegexRepl(t *testing.T) {
 	tests := []struct {
 		name string