sway: waybar: fix media to better handle multiple players

hosts/common/programs/default.nix

@@ -45,6 +45,7 @@
     ./nix-index.nix
     ./obsidian.nix
     ./offlineimap.nix
+    ./playerctl.nix
     ./rhythmbox.nix
     ./ripgrep.nix
     ./sfeed.nix

hosts/common/programs/playerctl.nix

@@ -0,0 +1,15 @@
+{ config, lib, pkgs, ... }:
+{
+  # TODO: give `sane.programs` native support for defining services
+  systemd.user.services.playerctld = lib.mkIf config.sane.programs.playerctl.enabled {
+    description = "playerctl daemon to keep track of which MPRIS players were recently active";
+    documentation = [ "https://github.com/altdesktop/playerctl/issues/161" ];
+    wantedBy = [ "default.target" ];
+    serviceConfig.ExecStart = "${config.sane.programs.playerctl.package}/bin/playerctld";
+    # serviceConfig.Type = "dbus";
+    # serviceConfig.BusName = "org.mpris.MediaPlayer2.Player";
+    serviceConfig.Type = "simple";  # playerctl also supports a --daemon option, idk if that's better
+    serviceConfig.Restart = "on-failure";
+    serviceConfig.RestartSec = "10s";
+  };
+}

hosts/modules/gui/sway/default.nix

@@ -171,6 +171,7 @@ in
           "swayidle"
           "wl-clipboard"
           "blueberry"  # GUI bluetooth manager
+          "playerctl"  # for waybar & particularly to have playerctld running
           # "mako"  # notification daemon
           "swaynotificationcenter"  # notification daemon
           # # "pavucontrol"

hosts/modules/gui/sway/waybar-media

@@ -0,0 +1,17 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p jq -p playerctl
+status=$(playerctl status 2> /dev/null | tr 'A-Z' 'a-z')
+if [ -z "$status" ]; then
+  status="inactive"
+fi
+
+artist=$(playerctl metadata artist 2> /dev/null)
+title=$(playerctl metadata title 2> /dev/null)
+
+text=
+if [ -n "$title" ]; then
+  text="$artist - $title"
+fi
+# waybar requires output to be on a single line.
+# `alt` key determines the icon
+jq --null-input --compact-output --arg status "$status" --arg text "$text" '{ "text": $text, "alt": $status }'

hosts/modules/gui/sway/waybar-top.nix

@@ -1,6 +1,14 @@
 # docs: <https://github.com/Alexays/Waybar/wiki/Configuration>
-# format specifiers: <https://fmt.dev/latest/syntax.html#syntax>
+# - custom modules: <https://github.com/Alexays/Waybar/wiki/Module:-Custom>
+# - format specifiers: <https://fmt.dev/latest/syntax.html#syntax>
 { lib, pkgs }:
+let
+  waybar-media = pkgs.static-nix-shell.mkBash {
+    pname = "waybar-media";
+    src = ./.;
+    pkgs = [ "jq" "playerctl" ];
+  };
+in
 {
   height = lib.mkDefault 40;
   modules-left = lib.mkDefault [ "sway/workspaces" ];
@@ -19,28 +27,36 @@
     max-length = 50;
   };
 
-  # include song artist/title.
-  # source: <https://www.reddit.com/r/swaywm/comments/ni0vso/waybar_spotify_tracktitle/>
   "custom/media" = {
-    exec = pkgs.writeShellScript "waybar-mediaplayer" ''
-      player_status=$(${pkgs.playerctl}/bin/playerctl status 2> /dev/null)
-      if [ "$player_status" = "Playing" ]; then
-        echo " $(${pkgs.playerctl}/bin/playerctl metadata artist) - $(${pkgs.playerctl}/bin/playerctl metadata title)"
-      elif [ "$player_status" = "Paused" ]; then
-        echo " $(${pkgs.playerctl}/bin/playerctl metadata artist) - $(${pkgs.playerctl}/bin/playerctl metadata title)"
-      fi
-    '';
+    # this module shows the actively playing song
+    # - source: <https://www.reddit.com/r/swaywm/comments/ni0vso/waybar_spotify_tracktitle/>
+    # - alternative: <https://github.com/Alexays/Waybar/wiki/Module:-MPRIS>
+    # - alternative: <https://github.com/Alexays/Waybar/wiki/Module:-Custom#mpris-controller>
+    #
+    # N.B.: for this to behave well with multiple MPRIS clients,
+    # `playerctld` must be enabled. see: <https://github.com/altdesktop/playerctl/issues/161>
+    exec = "${waybar-media}/bin/waybar-media";
+    return-type = "json";
     interval = 2;
-    format = "{}";
-    # return-type = "json";
-    on-click = "${pkgs.playerctl}/bin/playerctl play-pause";
-    on-scroll-up = "${pkgs.playerctl}/bin/playerctl next";
-    on-scroll-down = "${pkgs.playerctl}/bin/playerctl previous";
+    format = "{icon}{}";
+    max-length = 50;
+    format-icons = {
+      playing = " ";
+      paused = " ";
+      inactive = "";
+    };
+    tooltip = false;
+    on-click = "playerctl play-pause";
+    on-scroll-up = "playerctl next";
+    on-scroll-down = "playerctl previous";
   };
   "custom/swaync" = {
     # source: <https://github.com/ErikReider/SwayNotificationCenter#waybar-example>
-    tooltip = false;
-    format = "{icon}";  # or "{icon} {}" to inclde notif count
+    exec-if = "which swaync-client";
+    exec = "swaync-client -swb";
+    return-type = "json";
+    escape = true;
+    format = "{icon}";  # or "{icon} {}" to include notif count
     format-icons = {
       notification = "<span foreground='red'><sup></sup></span>";
       none = "";
@@ -51,12 +67,9 @@
       dnd-inhibited-notification = "<span foreground='red'><sup></sup></span>";
       dnd-inhibited-none = "";
     };
-    return-type = "json";
-    exec-if = "which swaync-client";
-    exec = "swaync-client -swb";
+    tooltip = false;
     on-click = "swaync-client -t -sw";
     on-click-right = "swaync-client -d -sw";
-    escape = true;
   };
   network = {
     # docs: <https://github.com/Alexays/Waybar/blob/master/man/waybar-network.5.scd>