feat: watch playlists (#2)

go.mod

@@ -1,3 +1,5 @@
 module github.com/soldiermoth/hlsq
 
 go 1.14
+
+require golang.org/x/text v0.3.4

go.sum

@@ -0,0 +1,3 @@
+golang.org/x/text v0.3.4 h1:0YWbFKbhXG/wIiuHDSKpS0Iy7FSA+u45VtBMfQcFTTc=
+golang.org/x/text v0.3.4/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

hlsq.go

@@ -5,9 +5,13 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"net/http"
 	"os"
+	"strconv"
+	"time"
 
 	"github.com/soldiermoth/hlsq/hlsqlib"
+	"golang.org/x/text/unicode/norm"
 )
 
 func main() {
@@ -20,6 +24,8 @@ func main() {
 		query       = flag.String("query", "", "Query")
 		chomp       = flag.Bool("chomp", false, "Removes whitespace")
 		demuxed     = flag.Bool("demuxed", false, "Set to demuxed colors")
+		watch       = flag.Bool("watch", false, "Continuously watch the playlist (requires url)")
+		url         = flag.String("url", "", "URL of the manifest to watch (required to watch)")
 		r           io.Reader
 		err         error
 	)
@@ -52,6 +58,8 @@ func main() {
 		if r, err = os.Open(args[0]); err != nil {
 			log.Fatalf("could not open file %q err=%q", args[0], err)
 		}
+	} else if *watch && *url != "" {
+		r = getManifest(*url)
 	} else {
 		log.Fatal("expected 1 argument of the m3u8 file to process or to read from stdin")
 	}
@@ -71,9 +79,59 @@ func main() {
 		}
 		opts = append([]hlsqlib.SerializeOption{hlsqlib.AttrMatch(queryFunc)}, opts...)
 	}
-	for scanner.Scan() {
-		line := scanner.Tag()
-		hlsqlib.Serialize(os.Stdout, line, opts...)
+	if *watch && *url != "" {
+		opts = append(opts, hlsqlib.Chomp)
+		var updatePeriod time.Duration
+		seen := make(map[string]bool)
+		ignoredTagsOnUpdate := []string{
+			"#EXTM3U",
+			"#EXT-X-VERSION",
+			"#EXT-X-DISCONTINUITY-SEQUENCE",
+			"#EXT-X-PUBLISHED-TIME",
+			"#EXT-X-TARGETDURATION",
+			"#EXT-X-MEDIA-SEQUENCE",
+			"#EXT-X-PROGRAM-DATE-TIME",
+			"#EXT-X-KEY",
+		}
+		for scanner.Scan() {
+			line := scanner.Tag()
+			if line.Name == "#EXT-X-TARGETDURATION" {
+				d, _ := strconv.Atoi(line.Attrs[0].Key)
+				updatePeriod = time.Duration(d) * time.Second
+			}
+			if line.Name == "#EXTINF" {
+				segment := norm.NFC.Bytes([]byte(string(line.Trailing[0])))
+				seen[string(segment)] = true
+			}
+			hlsqlib.Serialize(os.Stdout, line, opts...)
+		}
+		for range time.Tick(updatePeriod) {
+			r = getManifest(*url)
+			scanner = hlsqlib.NewScanner(r)
+			updated := false
+			for scanner.Scan() {
+				line := scanner.Tag()
+				if stringInSlice(line.Name, ignoredTagsOnUpdate) {
+					continue
+				}
+				segment := norm.NFC.Bytes([]byte(string(line.Trailing[0])))
+				if line.Name == "#EXTINF" && seen[string(segment)] {
+					continue
+				} else if line.Name == "#EXTINF" && !seen[string(segment)] {
+					seen[string(segment)] = true
+				}
+				hlsqlib.Serialize(os.Stdout, line, opts...)
+				updated = true
+			}
+			if !updated {
+				fmt.Println("manifest did not change this period")
+			}
+		}
+	} else {
+		for scanner.Scan() {
+			line := scanner.Tag()
+			hlsqlib.Serialize(os.Stdout, line, opts...)
+		}
 	}
 	fmt.Fprintln(os.Stdout)
 }
@@ -86,9 +144,27 @@ func (f flagColor) String() string {
 	}
 	return hlsqlib.NewColorizer(*f.Color).S("Example")
 }
+
 func (f flagColor) Set(s string) (err error) {
 	if s != "" {
 		*f.Color, err = hlsqlib.ParseColor(s)
 	}
 	return
 }
+
+func getManifest(url string) io.ReadCloser {
+	resp, err := http.Get(url)
+	if err != nil {
+		log.Fatalf("could not fetch manifest: %v\n", err)
+	}
+	return resp.Body
+}
+
+func stringInSlice(a string, list []string) bool {
+	for _, b := range list {
+		if b == a {
+			return true
+		}
+	}
+	return false
+}