diff --git a/lib/app.go b/lib/app.go
index 8574bdf..ea98230 100644
--- a/lib/app.go
+++ b/lib/app.go
@@ -1,7 +1,8 @@
-package pkg
+package lib
 
 type App struct {
-
 }
 
-
+func NewApp() App {
+	return App{}
+}
diff --git a/lib/download.go b/lib/download.go
index 9688424..b5aac7e 100644
--- a/lib/download.go
+++ b/lib/download.go
@@ -1,4 +1,4 @@
-package pkg
+package lib
 
 import (
 	"errors"
@@ -11,24 +11,37 @@ const (
 	DEFAULT_DOWNLOAD_OUTPUT_FOLDER = "."
 )
 
-func Download(app *App, url string, output_folder string, service string) error {
-	if output_folder == "" {
-		output_folder = DEFAULT_DOWNLOAD_OUTPUT_FOLDER
+type AvailableServices int
+
+const (
+	AvailableServicesTidal = iota
+)
+
+func ParseAvailableServices(service string) (AvailableServices, error) {
+	switch service {
+	case "tidal":
+		return AvailableServicesTidal, nil
+		break
+	}
+	return AvailableServicesTidal, errors.New("Invalid service.")
+}
+
+type DownloadRequest struct {
+	Service AvailableServices
+}
+
+func (app *App) Download(url string, outputFolder string, serviceString string) error {
+	if outputFolder == "" {
+		outputFolder = DEFAULT_DOWNLOAD_OUTPUT_FOLDER
 	}
 
-	if service == "" {
-		service = DEFAULT_DOWNLOAD_SERVICE
+	if serviceString == "" {
+		serviceString = DEFAULT_DOWNLOAD_SERVICE
 	}
 
-	if service == "amazon" || service == "qobuz" {
-		isInstalled, err := app.CheckFFmpegInstalled()
-		if err != nil {
-			return err
-		}
-
-		if !isInstalled {
-			return errors.New("FFmpeg is not installed.")
-		}
+	service, err := ParseAvailableServices(serviceString)
+	if err != nil {
+		return err
 	}
 
 	url_type := GetUrlType(url)
@@ -41,7 +54,7 @@ func Download(app *App, url string, output_folder string, service string) error
 		}
 
 		track := metadata.Track
-		downloadRequest := app.DownloadRequest{
+		downloadRequest := DownloadRequest{
 			Service:     service,
 			TrackName:   track.Name,
 			ArtistName:  track.Artists,
@@ -49,7 +62,7 @@ func Download(app *App, url string, output_folder string, service string) error
 			AlbumArtist: track.AlbumArtist,
 			ReleaseDate: track.ReleaseDate,
 			CoverURL:    track.Images,
-			OutputDir:   output_folder,
+			OutputDir:   outputFolder,
 			SpotifyID:   track.SpotifyID,
 		}
 
@@ -65,7 +78,7 @@ func Download(app *App, url string, output_folder string, service string) error
 		for idx, track := range metadata.TrackList {
 			fmt.Println("[" + strconv.Itoa(idx+1) + "/" + trackListSize + "] " + track.Name + " - " + track.Artists)
 
-			downloadRequest := app.DownloadRequest{
+			downloadRequest := DownloadRequest{
 				Service:      service,
 				TrackName:    track.Name,
 				ArtistName:   track.Artists,
@@ -73,7 +86,7 @@ func Download(app *App, url string, output_folder string, service string) error
 				AlbumArtist:  track.AlbumArtist,
 				ReleaseDate:  track.ReleaseDate,
 				CoverURL:     track.Images,
-				OutputDir:    output_folder,
+				OutputDir:    outputFolder,
 				SpotifyID:    track.SpotifyID,
 				PlaylistName: metadata.Info.Owner.Name,
 			}
@@ -89,3 +102,7 @@ func Download(app *App, url string, output_folder string, service string) error
 
 	return errors.New("Invalid URL.")
 }
+
+func (app *App) DownloadTrack(dr DownloadRequest) {
+
+}
diff --git a/lib/metadata.go b/lib/metadata.go
index 725efc1..43deb8a 100644
--- a/lib/metadata.go
+++ b/lib/metadata.go
@@ -1,4 +1,4 @@
-package pkg
+package lib
 
 import (
 	"encoding/json"
@@ -73,7 +73,7 @@ func GetMetadata[T MetadataPlaylist | MetadataSong](app *App, url string) (T, er
 	return result, nil
 }
 
-func PrintMetadata(app *App, url string) error {
+func (app *App) PrintMetadata(url string) error {
 	switch GetUrlType(url) {
 	case UrlTypeTrack:
 		metadata, err := GetMetadata[MetadataSong](app, url)
@@ -117,4 +117,3 @@ Cover: %s`
 
 	return errors.New("Invalid URL.")
 }
-
diff --git a/lib/services.go b/lib/services.go
new file mode 100644
index 0000000..55c21f8
--- /dev/null
+++ b/lib/services.go
@@ -0,0 +1 @@
+package lib
diff --git a/lib/utils.go b/lib/utils.go
index 9cce6f2..64c243b 100644
--- a/lib/utils.go
+++ b/lib/utils.go
@@ -1,4 +1,4 @@
-package pkg
+package lib
 
 import (
 	"strings"
diff --git a/main.go b/main.go
index 5d5cae9..71acc13 100644
--- a/main.go
+++ b/main.go
@@ -10,7 +10,7 @@ import (
 )
 
 func main() {
-	var output_folder, service string
+	var outputFolder, service string
 
 	app := lib.NewApp()
 
@@ -29,7 +29,7 @@ func main() {
 						Name:        "output",
 						Aliases:     []string{"o"},
 						Usage:       "set output folder",
-						Destination: &output_folder,
+						Destination: &outputFolder,
 					},
 					&cli.StringFlag{
 						Name:        "service",
@@ -40,7 +40,7 @@ func main() {
 				},
 				Action: func(ctx context.Context, cmd *cli.Command) error {
 					song_url := cmd.Args().First()
-					err := pkg.Download(app, song_url, output_folder, service)
+					err := app.Download(song_url, outputFolder, service)
 					return err
 				},
 			},
@@ -50,7 +50,7 @@ func main() {
 				Usage:   "view song metadata",
 				Action: func(ctx context.Context, cmd *cli.Command) error {
 					url := cmd.Args().First()
-					return pkg.PrintMetadata(app, url)
+					return app.PrintMetadata(url)
 				},
 			},
 		},