From 75e107da0c631dcaf0598850e1866a18cd85008a Mon Sep 17 00:00:00 2001
From: Thomas Dupas <thomas.dupas@dnsbelgium.be>
Date: Wed, 20 Apr 2022 16:38:30 +0200
Subject: [PATCH] allow inverted sorting if needed

---
 README.md                                     |  1 +
 internal/config/config.go                     |  6 +++
 internal/controllers/reversed-s3-objects.go   | 47 +++++++++++++++++++
 .../controllers/reversed-s3-objects_test.go   | 35 ++++++++++++++
 internal/controllers/s3.go                    |  6 ++-
 5 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 internal/controllers/reversed-s3-objects.go
 create mode 100644 internal/controllers/reversed-s3-objects_test.go

diff --git a/README.md b/README.md
index d730fa6..ccd4654 100644
--- a/README.md
+++ b/README.md
@@ -58,6 +58,7 @@ MAX_IDLE_CONNECTIONS      | Allowed number of idle connections to the S3 storage
 IDLE_CONNECTION_TIMEOUT   | Allowed timeout to the S3 storage.                |          | 10
 DISABLE_COMPRESSION       | If true will pass encoded content through as-is.  |          | true
 INSECURE_TLS              | If true it will skip cert checks                  |          | false
+REVERSE_SORTING           | If true it will sort in descending order          |          | false
 
 ### 2. Run the application
 
diff --git a/internal/config/config.go b/internal/config/config.go
index 6e80c32..8594fbd 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -46,6 +46,7 @@ type config struct { // nolint
 	DisableCompression bool          // DISABLE_COMPRESSION
 	InsecureTLS        bool          // Disables TLS validation on request endpoints.
 	JwtSecretKey       string        // JWT_SECRET_KEY
+	ReverseSorting     bool          // REVERSE_SORTING
 }
 
 // Setup configurations with environment variables
@@ -98,6 +99,10 @@ func Setup() {
 	if b, err := strconv.ParseBool(os.Getenv("INSECURE_TLS")); err == nil {
 		insecureTLS = b
 	}
+	reverseSorting := false
+	if b, err := strconv.ParseBool(os.Getenv("REVERSE_SORTING")); err == nil {
+		reverseSorting = b
+	}
 	Config = &config{
 		AwsRegion:          region,
 		AwsAPIEndpoint:     os.Getenv("AWS_API_ENDPOINT"),
@@ -128,6 +133,7 @@ func Setup() {
 		DisableCompression: disableCompression,
 		InsecureTLS:        insecureTLS,
 		JwtSecretKey:       os.Getenv("JWT_SECRET_KEY"),
+		ReverseSorting:     reverseSorting,
 	}
 	// Proxy
 	log.Printf("[config] Proxy to %v", Config.S3Bucket)
diff --git a/internal/controllers/reversed-s3-objects.go b/internal/controllers/reversed-s3-objects.go
new file mode 100644
index 0000000..88cfeb1
--- /dev/null
+++ b/internal/controllers/reversed-s3-objects.go
@@ -0,0 +1,47 @@
+package controllers
+
+import (
+	"strings"
+	"unicode"
+)
+
+type reversedS3objects []string
+
+func (s reversedS3objects) Len() int {
+	return len(s)
+}
+func (s reversedS3objects) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+func (s reversedS3objects) Less(i, j int) bool {
+	if strings.Contains(s[i], "/") {
+		if !strings.Contains(s[j], "/") {
+			return true
+		}
+	} else {
+		if strings.Contains(s[j], "/") {
+			return false
+		}
+	}
+	irs := []rune(s[i])
+	jrs := []rune(s[j])
+
+	max := len(irs)
+	if max > len(jrs) {
+		max = len(jrs)
+	}
+	for idx := 0; idx < max; idx++ {
+		ir := irs[idx]
+		jr := jrs[idx]
+		irl := unicode.ToLower(ir)
+		jrl := unicode.ToLower(jr)
+
+		if irl != jrl {
+			return irl > jrl
+		}
+		if ir != jr {
+			return ir > jr
+		}
+	}
+	return false
+}
diff --git a/internal/controllers/reversed-s3-objects_test.go b/internal/controllers/reversed-s3-objects_test.go
new file mode 100644
index 0000000..be40567
--- /dev/null
+++ b/internal/controllers/reversed-s3-objects_test.go
@@ -0,0 +1,35 @@
+package controllers
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSortByReversedS3objects1(t *testing.T) {
+	expected := []string{"3", "2", "1"}
+
+	actual := []string{"3", "1", "2"}
+	sort.Sort(reversedS3objects{(actual))
+
+	assert.Equal(t, expected, actual)
+}
+
+func TestSortByReversedS3objects2(t *testing.T) {
+	expected := []string{"/20", "/10", "/101"}
+
+	actual := []string{"/20", "/101", "/10"}
+	sort.Sort(reversedS3objects(actual))
+
+	assert.Equal(t, expected, actual)
+}
+
+func TestSortByReversedS3objects3(t *testing.T) {
+	expected := []string{"/200/10", "/101/1", "/10/2"}
+
+	actual := []string{"/200/10", "/10/2", "/101/1"}
+	sort.Sort(reversedS3objects(actual))
+
+	assert.Equal(t, expected, actual)
+}
diff --git a/internal/controllers/s3.go b/internal/controllers/s3.go
index 7243e7c..0b9084e 100644
--- a/internal/controllers/s3.go
+++ b/internal/controllers/s3.go
@@ -194,7 +194,11 @@ func convertToMaps(s3output *s3.ListObjectsOutput, prefix string) ([]string, map
 	for file := range candidates {
 		files = append(files, file)
 	}
-	sort.Sort(s3objects(files))
+	if config.Config.ReverseSorting {
+		sort.Sort(reversedS3objects(files))
+	} else {
+		sort.Sort(s3objects(files))
+	}
 
 	return files, updatedAt
 }