From 2f7577f7511acd892c499a32bc70ef833ebbd1cf Mon Sep 17 00:00:00 2001
From: Mathis Engelbart <mathis.engelbart@gmail.com>
Date: Thu, 16 Jan 2025 17:10:59 +0100
Subject: [PATCH] Removes duplicated unwrapper code

---
 internal/sequencenumber/unwrapper_test.go |  8 ++++
 pkg/rfc8888/stream_log.go                 |  7 +--
 pkg/rfc8888/unwrapper.go                  | 42 -----------------
 pkg/rfc8888/unwrapper_test.go             | 57 -----------------------
 4 files changed, 12 insertions(+), 102 deletions(-)
 delete mode 100644 pkg/rfc8888/unwrapper.go
 delete mode 100644 pkg/rfc8888/unwrapper_test.go

diff --git a/internal/sequencenumber/unwrapper_test.go b/internal/sequencenumber/unwrapper_test.go
index e5129b28..47c4154e 100644
--- a/internal/sequencenumber/unwrapper_test.go
+++ b/internal/sequencenumber/unwrapper_test.go
@@ -83,6 +83,14 @@ func TestUnwrapper(t *testing.T) {
 			input:    []uint16{32767, 0},
 			expected: []int64{32767, 0},
 		},
+		{
+			input:    []uint16{0, 1, 4, 3, 2, 5},
+			expected: []int64{0, 1, 4, 3, 2, 5},
+		},
+		{
+			input:    []uint16{65534, 0, 1, 65535, 4, 3, 2, 5},
+			expected: []int64{65534, 65536, 65537, 65535, 65540, 65539, 65538, 65541},
+		},
 		{
 			input: []uint16{
 				0, 32767, 32768, 32769, 32770,
diff --git a/pkg/rfc8888/stream_log.go b/pkg/rfc8888/stream_log.go
index 8dfb14fc..2d18d9c6 100644
--- a/pkg/rfc8888/stream_log.go
+++ b/pkg/rfc8888/stream_log.go
@@ -6,6 +6,7 @@ package rfc8888
 import (
 	"time"
 
+	"github.com/pion/interceptor/internal/sequencenumber"
 	"github.com/pion/rtcp"
 )
 
@@ -13,7 +14,7 @@ const maxReportsPerReportBlock = 16384
 
 type streamLog struct {
 	ssrc                       uint32
-	sequence                   unwrapper
+	sequence                   sequencenumber.Unwrapper
 	init                       bool
 	nextSequenceNumberToReport int64 // next to report
 	lastSequenceNumberReceived int64 // highest received
@@ -23,7 +24,7 @@ type streamLog struct {
 func newStreamLog(ssrc uint32) *streamLog {
 	return &streamLog{
 		ssrc:                       ssrc,
-		sequence:                   unwrapper{},
+		sequence:                   sequencenumber.Unwrapper{},
 		init:                       false,
 		nextSequenceNumberToReport: 0,
 		lastSequenceNumberReceived: 0,
@@ -32,7 +33,7 @@ func newStreamLog(ssrc uint32) *streamLog {
 }
 
 func (l *streamLog) add(ts time.Time, sequenceNumber uint16, ecn uint8) {
-	unwrappedSequenceNumber := l.sequence.unwrap(sequenceNumber)
+	unwrappedSequenceNumber := l.sequence.Unwrap(sequenceNumber)
 	if !l.init {
 		l.init = true
 		l.nextSequenceNumberToReport = unwrappedSequenceNumber
diff --git a/pkg/rfc8888/unwrapper.go b/pkg/rfc8888/unwrapper.go
deleted file mode 100644
index f15f33e6..00000000
--- a/pkg/rfc8888/unwrapper.go
+++ /dev/null
@@ -1,42 +0,0 @@
-// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
-// SPDX-License-Identifier: MIT
-
-package rfc8888
-
-const (
-	maxSequenceNumberPlusOne = int64(65536)
-	breakpoint               = 32768 // half of max uint16
-)
-
-type unwrapper struct {
-	init          bool
-	lastUnwrapped int64
-}
-
-func isNewer(value, previous uint16) bool {
-	if value-previous == breakpoint {
-		return value > previous
-	}
-	return value != previous && (value-previous) < breakpoint
-}
-
-func (u *unwrapper) unwrap(i uint16) int64 {
-	if !u.init {
-		u.init = true
-		u.lastUnwrapped = int64(i)
-		return u.lastUnwrapped
-	}
-
-	lastWrapped := uint16(u.lastUnwrapped)
-	delta := int64(i - lastWrapped)
-	if isNewer(i, lastWrapped) {
-		if delta < 0 {
-			delta += maxSequenceNumberPlusOne
-		}
-	} else if delta > 0 && u.lastUnwrapped+delta-maxSequenceNumberPlusOne >= 0 {
-		delta -= maxSequenceNumberPlusOne
-	}
-
-	u.lastUnwrapped += delta
-	return u.lastUnwrapped
-}
diff --git a/pkg/rfc8888/unwrapper_test.go b/pkg/rfc8888/unwrapper_test.go
deleted file mode 100644
index 3e7de924..00000000
--- a/pkg/rfc8888/unwrapper_test.go
+++ /dev/null
@@ -1,57 +0,0 @@
-// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
-// SPDX-License-Identifier: MIT
-
-package rfc8888
-
-import (
-	"fmt"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestUnwrapper(t *testing.T) {
-	cases := []struct {
-		input    []uint16
-		expected []int64
-	}{
-		{
-			input:    []uint16{},
-			expected: []int64{},
-		},
-		{
-			input:    []uint16{0, 1, 2, 3, 4},
-			expected: []int64{0, 1, 2, 3, 4},
-		},
-		{
-			input:    []uint16{65534, 65535, 0, 1, 2},
-			expected: []int64{65534, 65535, 65536, 65537, 65538},
-		},
-		{
-			input:    []uint16{32769, 0},
-			expected: []int64{32769, 65536},
-		},
-		{
-			input:    []uint16{32767, 0},
-			expected: []int64{32767, 0},
-		},
-		{
-			input:    []uint16{0, 1, 4, 3, 2, 5},
-			expected: []int64{0, 1, 4, 3, 2, 5},
-		},
-		{
-			input:    []uint16{65534, 0, 1, 65535, 4, 3, 2, 5},
-			expected: []int64{65534, 65536, 65537, 65535, 65540, 65539, 65538, 65541},
-		},
-	}
-	for i, tc := range cases {
-		t.Run(fmt.Sprintf("%v", i), func(t *testing.T) {
-			u := &unwrapper{}
-			result := []int64{}
-			for _, i := range tc.input {
-				result = append(result, u.unwrap(i))
-			}
-			assert.Equal(t, tc.expected, result)
-		})
-	}
-}