feat(tracker): implement saving and loading a song file

tracker/files.go

@@ -0,0 +1,51 @@
+package tracker
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"path/filepath"
+
+	"gopkg.in/yaml.v3"
+
+	"github.com/sqweek/dialog"
+	"github.com/vsariola/sointu"
+)
+
+func (t *Tracker) LoadSongFile() {
+	filename, err := dialog.File().Filter("Sointu YAML song", "yml").Filter("Sointu JSON song", "json").Title("Load song").Load()
+	if err != nil {
+		return
+	}
+	bytes, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return
+	}
+	var song sointu.Song
+	if errJSON := json.Unmarshal(bytes, &song); errJSON != nil {
+		if errYaml := yaml.Unmarshal(bytes, &song); errYaml != nil {
+			return
+		}
+	}
+	t.LoadSong(song)
+}
+
+func (t *Tracker) SaveSongFile() {
+	filename, err := dialog.File().Filter("Sointu YAML song", "yml").Filter("Sointu JSON song", "json").Title("Save song").Save()
+	if err != nil {
+		return
+	}
+	var extension = filepath.Ext(filename)
+	var contents []byte
+	if extension == "json" {
+		contents, err = json.Marshal(t.song)
+	} else {
+		contents, err = yaml.Marshal(t.song)
+	}
+	if err != nil {
+		return
+	}
+	if extension == "" {
+		filename = filename + ".yml"
+	}
+	ioutil.WriteFile(filename, contents, 0644)
+}