waybar: add module

PR #1329

4 files changed, 382 insertions, 0 deletions

diff --git a/modules/lib/maintainers.nix b/modules/lib/maintainers.nix
index 49d14ef0638..ff046360071 100644
--- a/modules/lib/maintainers.nix
+++ b/modules/lib/maintainers.nix
@@ -25,4 +25,14 @@
     github = "cwyc";
     githubId = 16950437;
   };
+  berbiche = {
+    name = "Nicolas Berbiche";
+    email = "berbiche@users.noreply.github.com";
+    github = "berbiche";
+    githubId = 20448408;
+    keys = [{
+      longkeyid = "rsa4096/0xB461292445C6E696";
+      fingerprint = "D446 E58D 87A0 31C7 EC15  88D7 B461 2924 45C6 E696";
+    }];
+  };
 }
diff --git a/modules/misc/news.nix b/modules/misc/news.nix
index 62f57a44cec..4ec6fc2d6dd 100644
--- a/modules/misc/news.nix
+++ b/modules/misc/news.nix
@@ -1619,6 +1619,14 @@ in
           A new module is available: 'services.dropbox'.
         '';
       }
+
+      {
+        time = "2020-08-13T22:15:27+00:00";
+        condition = hostPlatform.isLinux;
+        message = ''
+          A new module is available: 'programs.waybar'
+        '';
+      }
     ];
   };
 }
diff --git a/modules/modules.nix b/modules/modules.nix
index 76ff5aaa8c0..41877c5e21a 100644
--- a/modules/modules.nix
+++ b/modules/modules.nix
@@ -118,6 +118,7 @@ let
     (loadModule ./programs/vim.nix { })
     (loadModule ./programs/vscode.nix { })
     (loadModule ./programs/vscode/haskell.nix { })
+    (loadModule ./programs/waybar.nix { condition = hostPlatform.isLinux; })
     (loadModule ./programs/z-lua.nix { })
     (loadModule ./programs/zathura.nix { })
     (loadModule ./programs/zoxide.nix { })
diff --git a/modules/programs/waybar.nix b/modules/programs/waybar.nix
new file mode 100644
index 00000000000..369f6e32aba
--- /dev/null
+++ b/modules/programs/waybar.nix
@@ -0,0 +1,363 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+let
+  cfg = config.programs.waybar;
+
+  # Used when generating warnings
+  modulesPath = "programs.waybar.settings.[].modules";
+
+  # Taken from <https://github.com/Alexays/Waybar/blob/adaf84304865e143e4e83984aaea6f6a7c9d4d96/src/factory.cpp>
+  defaultModuleNames = [
+    "sway/mode"
+    "sway/workspaces"
+    "sway/window"
+    "wlr/taskbar"
+    "idle_inhibitor"
+    "memory"
+    "cpu"
+    "clock"
+    "disk"
+    "tray"
+    "network"
+    "backlight"
+    "pulseaudio"
+    "mpd"
+    "temperature"
+    "bluetooth"
+    "battery"
+  ];
+
+  isValidCustomModuleName = x:
+    elem x defaultModuleNames || (hasPrefix "custom/" x && stringLength x > 7);
+
+  margins = let
+    mkMargin = name: {
+      "margin-${name}" = mkOption {
+        type = types.nullOr types.int;
+        default = null;
+        example = 10;
+        description = "Margins value without unit.";
+      };
+    };
+    margins = map mkMargin [ "top" "left" "bottom" "right" ];
+  in foldl' mergeAttrs { } margins;
+
+  waybarBarConfig = with lib.types;
+    submodule {
+      options = {
+        layer = mkOption {
+          type = nullOr (enum [ "top" "bottom" ]);
+          default = null;
+          description = ''
+            Decide if the bar is displayed in front (<code>"top"</code>)
+            of the windows or behind (<code>"bottom"</code>).
+          '';
+          example = "top";
+        };
+
+        output = mkOption {
+          type = nullOr (either str (listOf str));
+          default = null;
+          example = literalExample ''
+            [ "DP-1" "!DP-2" "!DP-3" ]
+          '';
+          description = ''
+            Specifies on which screen this bar will be displayed.
+            Exclamation mark(!) can be used to exclude specific output.
+          '';
+        };
+
+        position = mkOption {
+          type = nullOr (enum [ "top" "bottom" "left" "right" ]);
+          default = null;
+          example = "right";
+          description = "Bar position relative to the output.";
+        };
+
+        height = mkOption {
+          type = nullOr ints.unsigned;
+          default = null;
+          example = 5;
+          description =
+            "Height to be used by the bar if possible. Leave blank for a dynamic value.";
+        };
+
+        width = mkOption {
+          type = nullOr ints.unsigned;
+          default = null;
+          example = 5;
+          description =
+            "Width to be used by the bar if possible. Leave blank for a dynamic value.";
+        };
+
+        modules-left = mkOption {
+          type = nullOr (listOf str);
+          default = null;
+          description = "Modules that will be displayed on the left.";
+          example = literalExample ''
+            [ "sway/workspaces" "sway/mode" "wlr/taskbar" ]
+          '';
+        };
+
+        modules-center = mkOption {
+          type = nullOr (listOf str);
+          default = null;
+          description = "Modules that will be displayed in the center.";
+          example = literalExample ''
+            [ "sway/window" ]
+          '';
+        };
+
+        modules-right = mkOption {
+          type = nullOr (listOf str);
+          default = null;
+          description = "Modules that will be displayed on the right.";
+          example = literalExample ''
+            [ "mpd" "custom/mymodule#with-css-id" "temperature" ]
+          '';
+        };
+
+        modules = mkOption {
+          type = attrsOf unspecified;
+          default = { };
+          description = "Modules configuration.";
+          example = literalExample ''
+            {
+              "sway/window" = {
+                max-length = 50;
+              };
+              "clock" = {
+                format-alt = "{:%a, %d. %b  %H:%M}";
+              };
+            }
+          '';
+        };
+
+        margin = mkOption {
+          type = nullOr str;
+          default = null;
+          description = "Margins value using the CSS format without units.";
+          example = "20 5";
+        };
+
+        inherit (margins) margin-top margin-left margin-bottom margin-right;
+
+        name = mkOption {
+          type = nullOr str;
+          default = null;
+          description =
+            "Optional name added as a CSS class, for styling multiple waybars.";
+          example = "waybar-1";
+        };
+
+        gtk-layer-shell = mkOption {
+          type = nullOr bool;
+          default = null;
+          example = false;
+          description =
+            "Option to disable the use of gtk-layer-shell for popups.";
+        };
+      };
+    };
+in {
+  meta.maintainers = [ hm.maintainers.berbiche ];
+
+  options.programs.waybar = with lib.types; {
+    enable = mkEnableOption "Waybar";
+
+    package = mkOption {
+      type = package;
+      default = pkgs.waybar;
+      defaultText = literalExample "${pkgs.waybar}";
+      description = ''
+        Waybar package to use. Set to <code>null</code> to use the default module.
+      '';
+    };
+
+    settings = mkOption {
+      type = listOf waybarBarConfig;
+      default = [ ];
+      description = ''
+        Configuration for Waybar, see <link
+          xlink:href="https://github.com/Alexays/Waybar/wiki/Configuration"/>
+        for supported values.
+      '';
+      example = literalExample ''
+        [
+          {
+            layer = "top";
+            position = "top";
+            height = 30;
+            output = [
+              "eDP-1"
+              "HDMI-A-1"
+            ];
+            modules-left = [ "sway/workspaces" "sway/mode" "wlr/taskbar" ];
+            modules-center = [ "sway/window" "custom/hello-from-waybar" ];
+            modules-right = [ "mpd" "custom/mymodule#with-css-id" "temperature" ];
+            modules = {
+              "sway/workspaces" = {
+                disable-scroll = true;
+                all-outputs = true;
+              };
+              "custom/hello-from-waybar" = {
+                format = "hello {}";
+                max-length = 40;
+                interval = "once";
+                exec = pkgs.writeShellScript "hello-from-waybar" '''
+                  echo "from within waybar"
+                ''';
+              };
+            };
+          }
+        ]
+      '';
+    };
+
+    systemd.enable = mkEnableOption "Waybar systemd integration";
+
+    style = mkOption {
+      type = nullOr str;
+      default = null;
+      description = ''
+        CSS style of the bar.
+        See <link xlink:href="https://github.com/Alexays/Waybar/wiki/Configuration"/>
+        for the documentation.
+      '';
+      example = ''
+        * {
+          border: none;
+          border-radius: 0;
+          font-family: Source Code Pro;
+        }
+        window#waybar {
+          background: #16191C;
+          color: #AAB2BF;
+        }
+        #workspaces button {
+          padding: 0 5px;
+        }
+      '';
+    };
+  };
+
+  config = let
+    # Inspired by https://github.com/NixOS/nixpkgs/pull/89781
+    writePrettyJSON = name: x:
+      pkgs.runCommandLocal name { } ''
+        ${pkgs.jq}/bin/jq . > $out <<<${escapeShellArg (builtins.toJSON x)}
+      '';
+
+    configSource = let
+      # Removes nulls because Waybar ignores them for most values
+      removeNulls = filterAttrs (_: v: v != null);
+
+      # Makes the actual valid configuration Waybar accepts
+      # (strips our custom settings before converting to JSON)
+      makeConfiguration = configuration:
+        let
+          # The "modules" option is not valid in the JSON
+          # as its descendants have to live at the top-level
+          settingsWithoutModules =
+            filterAttrs (n: _: n != "modules") configuration;
+          settingsModules =
+            optionalAttrs (configuration.modules != { }) configuration.modules;
+        in removeNulls (settingsWithoutModules // settingsModules);
+      # The clean list of configurations
+      finalConfiguration = map makeConfiguration cfg.settings;
+    in writePrettyJSON "waybar-config.json" finalConfiguration;
+
+    warnings = let
+      mkUnreferencedModuleWarning = name:
+        "The module '${name}' defined in '${modulesPath}' is not referenced "
+        + "in either `modules-left`, `modules-center` or `modules-right` of Waybar's options";
+      mkUndefinedModuleWarning = settings: name:
+        let
+          # Locations where the module is undefined (a combination modules-{left,center,right})
+          locations = flip filter [ "left" "center" "right" ]
+            (x: elem name settings."modules-${x}");
+          mkPath = loc: "'${modulesPath}-${loc}'";
+          # The modules-{left,center,right} configuration that includes
+          # an undefined module
+          path = concatMapStringsSep " and " mkPath locations;
+        in "The module '${name}' defined in ${path} is neither "
+        + "a default module or a custom module declared in '${modulesPath}'";
+      mkInvalidModuleNameWarning = name:
+        "The custom module '${name}' defined in '${modulesPath}' is not a valid "
+        + "module name. A custom module's name must start with 'custom/' "
+        + "like 'custom/mymodule' for instance";
+
+      # Find all modules in `modules-{left,center,right}` and `modules` not declared/referenced.
+      # `cfg.settings` is a list of Waybar configurations
+      # and we need to preserve the index for appropriate warnings
+      allFaultyModules = flip map cfg.settings (settings:
+        let
+          allModules = unique
+            (concatMap (x: attrByPath [ "modules-${x}" ] [ ] settings) [
+              "left"
+              "center"
+              "right"
+            ]);
+          declaredModules = attrNames settings.modules;
+          # Modules declared in `modules` but not referenced in `modules-{left,center,right}`
+          unreferencedModules = subtractLists allModules declaredModules;
+          # Modules listed in modules-{left,center,right} that are not default modules
+          nonDefaultModules = subtractLists defaultModuleNames allModules;
+          # Modules referenced in `modules-{left,center,right}` but not declared in `modules`
+          undefinedModules = subtractLists declaredModules nonDefaultModules;
+          # Check for invalid module names
+          invalidModuleNames =
+            filter (m: !isValidCustomModuleName m) (attrNames settings.modules);
+        in {
+          # The Waybar bar configuration (since config.settings is a list)
+          settings = settings;
+          undef = undefinedModules;
+          unref = unreferencedModules;
+          invalidName = invalidModuleNames;
+        });
+
+      allWarnings = flip concatMap allFaultyModules
+        ({ settings, undef, unref, invalidName }:
+          let
+            unreferenced = map mkUnreferencedModuleWarning unref;
+            undefined = map (mkUndefinedModuleWarning settings) undef;
+            invalid = map mkInvalidModuleNameWarning invalidName;
+          in undefined ++ unreferenced ++ invalid);
+    in allWarnings;
+
+  in mkIf cfg.enable (mkMerge [
+    { home.packages = [ cfg.package ]; }
+    (mkIf (cfg.settings != [ ]) {
+      # Generate warnings about defined but unreferenced modules
+      inherit warnings;
+
+      xdg.configFile."waybar/config".source = configSource;
+    })
+    (mkIf (cfg.style != null) {
+      xdg.configFile."waybar/style.css".text = cfg.style;
+    })
+    (mkIf cfg.systemd.enable {
+      systemd.user.services.waybar = {
+        Unit = {
+          Description =
+            "Highly customizable Wayland bar for Sway and Wlroots based compositors.";
+          Documentation = "https://github.com/Alexays/Waybar/wiki";
+          PartOf = [ "graphical-session.target" ];
+          Requisite = [ "dbus.service" ];
+          After = [ "dbus.service" ];
+        };
+
+        Service = {
+          Type = "dbus";
+          BusName = "fr.arouillard.waybar";
+          ExecStart = "${cfg.package}/bin/waybar";
+          Restart = "always";
+          RestartSec = "1sec";
+        };
+
+        Install = { WantedBy = [ "graphical-session.target" ]; };
+      };
+    })
+  ]);
+}