Moved Stream logic to engine layer

engine/stream.go

@@ -0,0 +1,56 @@
+package engine
+
+import (
+	"io"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+
+	"github.com/astaxie/beego"
+)
+
+// TODO Encapsulate as a io.Reader
+func Stream(path string, bitRate int, maxBitRate int, w io.Writer) error {
+	var f io.Reader
+	var err error
+	if maxBitRate > 0 && bitRate > maxBitRate {
+		f, err = downsample(path, maxBitRate)
+	} else {
+		f, err = os.Open(path)
+	}
+	if err != nil {
+		beego.Error("Error opening file", path, ":", err)
+		return err
+	}
+	if _, err = io.Copy(w, f); err != nil {
+		beego.Error("Error copying file", path, ":", err)
+		return err
+	}
+	return err
+}
+
+func downsample(path string, maxBitRate int) (f io.Reader, err error) {
+	cmdLine, args := createDownsamplingCommand(path, maxBitRate)
+
+	beego.Debug("Executing cmd:", cmdLine, args)
+	cmd := exec.Command(cmdLine, args...)
+	cmd.Stderr = os.Stderr
+	if f, err = cmd.StdoutPipe(); err != nil {
+		return f, err
+	}
+	return f, cmd.Start()
+}
+
+func createDownsamplingCommand(path string, maxBitRate int) (string, []string) {
+	cmd := beego.AppConfig.String("downsampleCommand")
+
+	split := strings.Split(cmd, " ")
+	for i, s := range split {
+		s = strings.Replace(s, "%s", path, -1)
+		s = strings.Replace(s, "%b", strconv.Itoa(maxBitRate), -1)
+		split[i] = s
+	}
+
+	return split[0], split[1:len(split)]
+}

engine/stream_test.go

@@ -0,0 +1,30 @@
+package engine
+
+import (
+	"testing"
+
+	. "github.com/deluan/gosonic/tests"
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestDownsampling(t *testing.T) {
+
+	Init(t, false)
+
+	Convey("Subject: createDownsamplingCommand", t, func() {
+
+		Convey("It should create a valid command line", func() {
+			cmd, args := createDownsamplingCommand("/music library/file.mp3", 128)
+
+			So(cmd, ShouldEqual, "ffmpeg")
+			So(args[0], ShouldEqual, "-i")
+			So(args[1], ShouldEqual, "/music library/file.mp3")
+			So(args[2], ShouldEqual, "-b:a")
+			So(args[3], ShouldEqual, "128k")
+			So(args[4], ShouldEqual, "mp3")
+			So(args[5], ShouldEqual, "-")
+		})
+
+	})
+
+}