Fixes #21; playlists are loaded in the background, with a spinner to …

…show the user the ongoing operation.

gui.go

@@ -71,7 +71,6 @@ const (
 )
 
 func InitGui(indexes *[]subsonic.SubsonicIndex,
-	playlists *[]subsonic.SubsonicPlaylist,
 	connection *subsonic.SubsonicConnection,
 	player *mpvplayer.Player,
 	logger *logger.Logger,
@@ -82,7 +81,7 @@ func InitGui(indexes *[]subsonic.SubsonicIndex,
 		eventLoop: nil, // initialized by initEventLoops()
 		mpvEvents: make(chan mpvplayer.UiEvent, 5),
 
-		playlists:   *playlists,
+		playlists:   []subsonic.SubsonicPlaylist{},
 		connection:  connection,
 		player:      player,
 		logger:      logger,
@@ -176,6 +175,8 @@ func InitGui(indexes *[]subsonic.SubsonicIndex,
 		SetFocus(rootFlex).
 		EnableMouse(true)
 
+	ui.playlistPage.UpdatePlaylists()
+
 	return ui
 }
 

page_playlist.go

@@ -4,6 +4,10 @@
 package main
 
 import (
+	"fmt"
+	"sync"
+	"time"
+
 	"github.com/gdamore/tcell/v2"
 	"github.com/rivo/tview"
 	"github.com/spezifisch/stmps/logger"
@@ -22,12 +26,16 @@ type PlaylistPage struct {
 	// external refs
 	ui     *Ui
 	logger logger.LoggerInterface
+
+	updatingMutex sync.Locker
+	isUpdating    bool
 }
 
 func (ui *Ui) createPlaylistPage() *PlaylistPage {
 	playlistPage := PlaylistPage{
-		ui:     ui,
-		logger: ui.logger,
+		ui:            ui,
+		logger:        ui.logger,
+		updatingMutex: &sync.Mutex{},
 	}
 
 	// left half: playlists
@@ -180,19 +188,77 @@ func (p *PlaylistPage) GetCount() int {
 }
 
 func (p *PlaylistPage) UpdatePlaylists() {
-	response, err := p.ui.connection.GetPlaylists()
-	if err != nil {
-		p.logger.PrintError("GetPlaylists", err)
+	// There's a potential race condition here and, albeit highly unlikely to ever get hit,
+	// we'll put in some protection
+	p.updatingMutex.Lock()
+	defer p.updatingMutex.Unlock()
+	if p.isUpdating {
+		return
 	}
-	p.ui.playlists = response.Playlists.Playlists
-
-	p.playlistList.Clear()
-	p.ui.addToPlaylistList.Clear()
+	p.isUpdating = true
+
+	var spinnerText []rune = []rune("⠁⠂⠄⡀⢀⠠⠐⠈")
+	playlistsButton := buttonOrder[2]
+	stop := make(chan bool)
+	go func() {
+		var idx int
+		timer := time.NewTicker(500 * time.Millisecond)
+		defer timer.Stop()
+		for {
+			select {
+			case <-timer.C:
+				p.ui.app.QueueUpdateDraw(func() {
+					var format string
+					if playlistsButton == p.ui.menuWidget.activeButton {
+						format = "%d: [::b][red]%c[white]%s[::-]"
+					} else {
+						format = "%d: [red]%c[white]%s"
+					}
+					label := fmt.Sprintf(format, 3, spinnerText[idx], playlistsButton)
+					p.ui.menuWidget.buttons[playlistsButton].SetLabel(label)
+					idx++
+					if idx > 7 {
+						idx = 0
+					}
+				})
+			case <-stop:
+				p.ui.app.QueueUpdateDraw(func() {
+					var format string
+					if playlistsButton == p.ui.menuWidget.activeButton {
+						format = "%d: [::b]%s[::-]"
+					} else {
+						format = "%d: %s"
+					}
+					label := fmt.Sprintf(format, 3, playlistsButton)
+					p.ui.menuWidget.buttons[playlistsButton].SetLabel(label)
+				})
+				close(stop)
+				return
+			}
+		}
+	}()
 
-	for _, playlist := range p.ui.playlists {
-		p.playlistList.AddItem(tview.Escape(playlist.Name), "", 0, nil)
-		p.ui.addToPlaylistList.AddItem(tview.Escape(playlist.Name), "", 0, nil)
-	}
+	go func() {
+		response, err := p.ui.connection.GetPlaylists()
+		if err != nil {
+			p.logger.PrintError("GetPlaylists", err)
+		}
+		p.updatingMutex.Lock()
+		defer p.updatingMutex.Unlock()
+		p.ui.playlists = response.Playlists.Playlists
+		p.ui.app.QueueUpdateDraw(func() {
+			p.playlistList.Clear()
+			p.ui.addToPlaylistList.Clear()
+
+			for _, playlist := range p.ui.playlists {
+				p.playlistList.AddItem(tview.Escape(playlist.Name), "", 0, nil)
+				p.ui.addToPlaylistList.AddItem(tview.Escape(playlist.Name), "", 0, nil)
+			}
+
+			p.isUpdating = false
+		})
+		stop <- true
+	}()
 }
 
 func (p *PlaylistPage) handleAddPlaylistSongToQueue() {

stmps.go

@@ -113,13 +113,6 @@ func main() {
 		os.Exit(1)
 	}
 
-	// TODO (B) loading playlists can take a long time on e.g. gonic if there are a lot of them; can it be done in the background?
-	playlistResponse, err := connection.GetPlaylists()
-	if err != nil {
-		fmt.Printf("Error fetching indexes from server: %s\n", err)
-		os.Exit(1)
-	}
-
 	if *list {
 		fmt.Printf("Index response:\n")
 		fmt.Printf("  Directory: %s\n", indexResponse.Directory.Name)
@@ -134,7 +127,12 @@ func main() {
 		for _, pl := range indexResponse.Indexes.Index {
 			fmt.Printf("    %s\n", pl.Name)
 		}
-		fmt.Printf("Playlist response:\n")
+		fmt.Printf("Playlist response: (this can take a while)\n")
+		playlistResponse, err := connection.GetPlaylists()
+		if err != nil {
+			fmt.Printf("Error fetching indexes from server: %s\n", err)
+			os.Exit(1)
+		}
 		fmt.Printf("  Directory: %s\n", playlistResponse.Directory.Name)
 		fmt.Printf("  Status: %s\n", playlistResponse.Status)
 		fmt.Printf("  Error: %s\n", playlistResponse.Error.Message)
@@ -181,7 +179,6 @@ func main() {
 	}
 
 	ui := InitGui(&indexResponse.Indexes.Index,
-		&playlistResponse.Playlists.Playlists,
 		connection,
 		player,
 		logger,

widget_help.go

@@ -9,7 +9,6 @@ import (
 	"github.com/rivo/tview"
 )
 
-// FIXME (A) invoking help and the dismissing it ('q') dismisses it forever (it can't be called back up)
 type HelpWidget struct {
 	Root *tview.Flex