streaming

commit 6f91fd7e149c0466f57b4288c77d2b2c0c35de78
parent c0a87bbed2f0947fe30ae80a5466bdae4de7621b
Author: blackfalcon <blackfalcon.ru@gmail.com>
Date:   Thu, 30 May 2024 14:03:17 -0300

m3u8: support writing SessionData

Resolves #8

Diffstat:
M
m3u8/m3u8.go
 | 
21
++++++++++++++++++---
A
m3u8/m3u8_test.go
 | 
64
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
m3u8/parse.go
 | 
1
+
M
m3u8/write.go
 | 
16
++++++++++++++++

4 files changed, 99 insertions(+), 3 deletions(-)
diff --git a/m3u8/m3u8.go b/m3u8/m3u8.go
@@ -283,8 +283,23 @@ type IFrameInfo Variant
 
 // SessionData represents the EXT-X-SESSION-DATA tag.
 type SessionData struct {
-	ID       string
-	Value    string
+	ID       string // This attribute is REQUIRED
+	Value    string // MUST contain either a VALUE or URI attribute, but not both
 	URI      string
-	Language string
+	Language string // This attribute is OPTIONAL.
+}
+
+func (sd SessionData) String() string {
+	var attrs []string
+	attrs = append(attrs, fmt.Sprintf("DATA-ID=%q", sd.ID))
+	if sd.Value != "" {
+		attrs = append(attrs, fmt.Sprintf("VALUE=%q", sd.Value))
+	}
+	if sd.URI != "" {
+		attrs = append(attrs, fmt.Sprintf("URI=%q", sd.URI))
+	}
+	if sd.Language != "" {
+		attrs = append(attrs, fmt.Sprintf("LANGUAGE=%q", sd.Language))
+	}
+	return strings.Join(attrs, ",")
 }
diff --git a/m3u8/m3u8_test.go b/m3u8/m3u8_test.go
@@ -0,0 +1,64 @@
+package m3u8
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestWriteSessionData(t *testing.T) {
+	var cases = []struct {
+		name  string
+		sd    SessionData
+		want  string
+		valid bool
+	}{
+		{
+			"all attributes set",
+			SessionData{ID: "1234", Value: "5678", Language: "indonesian"},
+			`#EXT-X-SESSION-DATA:DATA-ID="1234",VALUE="5678",LANGUAGE="indonesian"`,
+			true,
+		},
+		{
+			"language is optional",
+			SessionData{ID: "1234", URI: "hello/hi.json"},
+			`#EXT-X-SESSION-DATA:DATA-ID="1234",URI="hello/hi.json"`,
+			true,
+		},
+		{
+			"required attributes set(id, value or uri)",
+			SessionData{ID: "1234", Value: "5678"},
+			`#EXT-X-SESSION-DATA:DATA-ID="1234",VALUE="5678"`,
+			true,
+		},
+		{
+			"empty id",
+			SessionData{URI: "hello/hi.json"},
+			"",
+			false,
+		},
+		{
+			"both URI and Value set",
+			SessionData{ID: "1234", URI: "hello/hi.json", Value: "5678"},
+			"",
+			false,
+		},
+	}
+	for _, tt := range cases {
+		t.Run(tt.name, func(t *testing.T) {
+			buf := &bytes.Buffer{}
+			_, err := writeSessionData(buf, tt.sd)
+			if err == nil && !tt.valid {
+				t.Fatalf("nil error on invalid session data %v", tt.sd)
+			} else if err != nil && tt.valid {
+				t.Fatalf("non-nil error %v on valid session data", err)
+			}
+			got := strings.TrimSpace(buf.String()) // strip newlines
+			if got != tt.want {
+				t.Errorf("unexpected session data text")
+				t.Log("got:", got)
+				t.Log("want:", tt.want)
+			}
+		})
+	}
+}
diff --git a/m3u8/parse.go b/m3u8/parse.go
@@ -19,6 +19,7 @@ const (
 	tagMediaSequence       = "#EXT-X-MEDIA-SEQUENCE"       // RFC 8216, 4.3.3.2
 	tagEndList             = "#EXT-X-ENDLIST"              // RFC 8216, 4.4.3.4
 	tagIndependentSegments = "#EXT-X-INDEPENDENT-SEGMENTS" // RFC 8216, 4.3.5.1
+	tagSessionData         = "#EXT-X-SESSION-DATA"         // RFC 8216, 4.3.4.4
 )
 
 func ParsePlaylist(rd io.Reader) (*Playlist, error) {
diff --git a/m3u8/write.go b/m3u8/write.go
@@ -120,6 +120,12 @@ func Encode(w io.Writer, p *Playlist) error {
 		fmt.Fprintln(w, v.URI)
 	}
 
+	for i, sd := range p.SessionData {
+		if _, err := writeSessionData(w, sd); err != nil {
+			return fmt.Errorf("write session data %d: %w", i, err)
+		}
+	}
+
 	if p.End {
 		fmt.Fprintln(w, tagEndList)
 	}
@@ -173,3 +179,13 @@ func writeMap(w io.Writer, m Map) (n int, err error) {
 	}
 	return fmt.Fprintf(w, "%s:URI=%q\n", tagMap, m.URI)
 }
+
+func writeSessionData(w io.Writer, sd SessionData) (n int, err error) {
+	if sd.ID == "" {
+		return 0, fmt.Errorf("ID not set")
+	}
+	if sd.URI != "" && sd.Value != "" {
+		return 0, fmt.Errorf("only one of Value or URI may be set")
+	}
+	return fmt.Fprintf(w, "%s:%s\n", tagSessionData, sd)
+}