Add GTK application implementation

internal/gui/albumheaderbar.go

@@ -0,0 +1,42 @@
+package gui
+
+import (
+	"strings"
+
+	"github.com/diamondburned/gotk4-adwaita/pkg/adw"
+	"github.com/diamondburned/gotk4/pkg/gtk/v4"
+	"suruatoel.xyz/mcg/data"
+	"suruatoel.xyz/mcg/internal/common"
+)
+
+type albumHeaderbar struct {
+	*adw.Bin
+	titleLabel  *gtk.Label
+	artistLabel *gtk.Label
+	closeButton *gtk.Button
+}
+
+func newAlbumHeaderbar() *albumHeaderbar {
+	bar := albumHeaderbar{}
+	bar.loadWidgets()
+
+	return &bar
+}
+
+func (b *albumHeaderbar) loadWidgets() {
+	builder := gtk.NewBuilderFromString(data.AlbumHeaderbarXML)
+
+	b.Bin = builder.GetObject("McgAlbumHeaderbar").Cast().(*adw.Bin)
+	b.titleLabel = builder.GetObject("standalone_title").Cast().(*gtk.Label)
+	b.artistLabel = builder.GetObject("standalone_artist").Cast().(*gtk.Label)
+	b.closeButton = builder.GetObject("close_button").Cast().(*gtk.Button)
+}
+
+func (b *albumHeaderbar) SetAlbum(album *common.Album) {
+	b.titleLabel.SetText(album.Title())
+	b.artistLabel.SetText(strings.Join(album.Artists(), ", "))
+}
+
+func (b *albumHeaderbar) ConnectClose(callback func()) {
+	b.closeButton.ConnectClicked(callback)
+}