tmux: add module

This commit adds the tmux program to Home Manager.

In addition to configuring tmux, a user may specify tmux plugins from
Nixpkgs. These can be included in the list of `plugins` and can either
be a package (all tmux plugins live under `nixpkgs.tmuxPlugins.*`), or
an object which includes the plugin and an `extraConfig`, which will
be run immediately after sourcing the tmux plugin.

Finally, this commit introduces two nested programs which may be
enabled which depend on tmux: tmuxp and tmuxinator. These do not have
the ability to be configured, although this may be a future
contribution.

1 files changed, 148 insertions, 0 deletions

diff --git a/modules/programs/tmux.nix b/modules/programs/tmux.nix
new file mode 100644
index 00000000000..050168bedc8
--- /dev/null
+++ b/modules/programs/tmux.nix
@@ -0,0 +1,148 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.programs.tmux;
+
+  pluginName = p: if types.package.check p then p.name else p.plugin.name;
+
+  pluginModule = types.submodule {
+    options = {
+      plugin = mkOption {
+        type = types.package;
+        description = "Path of the configuration file to include.";
+      };
+
+      extraConfig = mkOption {
+        type = types.lines;
+        description = "Additional configuration for the associated plugin.";
+        default = "";
+      };
+    };
+  };
+
+in
+
+{
+  options = {
+    programs.tmux = {
+      enable = mkEnableOption "tmux";
+
+      package = mkOption {
+        type = types.package;
+        default = pkgs.tmux;
+        defaultText = "pkgs.tmux";
+        example = literalExample "pkgs.tmux";
+        description = "The tmux package to install";
+      };
+
+      sensibleOnTop = mkOption {
+        type = types.bool;
+        default = true;
+        description = ''
+          Run the sensible plugin at the top of the configuration. It
+          is possible to override the sensible settings using the
+          <option>programs.tmux.extraConfig</option> option.
+        '';
+      };
+
+      tmuxp.enable = mkEnableOption "tmuxp";
+
+      tmuxinator.enable = mkEnableOption "tmuxinator";
+
+      plugins = mkOption {
+        type = with types;
+          listOf (either package pluginModule)
+          // { description = "list of plugin packages or submodules"; };
+        description = ''
+          List of tmux plugins to be included at the end of your tmux
+          configuration. The sensible plugin, however, is defaulted to
+          run at the top of your configuration.
+        '';
+        default = [ ];
+        example = literalExample ''
+          with pkgs; [
+            tmuxPlugins.cpu
+            {
+              plugin = tmuxPlugins.resurrect;
+              extraConfig = "set -g @resurrect-strategy-nvim 'session'";
+            }
+            {
+              plugin = tmuxPlugins.continuum;
+              extraConfig = '''
+                set -g @continuum-restore 'on'
+                set -g @continuum-save-interval '60' # minutes
+              ''';
+            }
+          ]
+        '';
+      };
+
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        description = ''
+          Additional configuration to add to
+          <filename>tmux.conf</filename>.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable (
+    mkMerge [
+      {
+        home.packages = [ cfg.package ]
+          ++ optional cfg.tmuxinator.enable pkgs.tmuxinator
+          ++ optional cfg.tmuxp.enable      pkgs.tmuxp;
+
+          home.file.".tmux.conf".text = cfg.extraConfig;
+      }
+
+      (mkIf cfg.sensibleOnTop {
+        home.file.".tmux.conf".text = mkBefore ''
+          # ============================================= #
+          # Start with defaults from the Sensible plugin  #
+          # --------------------------------------------- #
+          run-shell ${pkgs.tmuxPlugins.sensible.rtp}
+          # ============================================= #
+        '';
+      })
+
+      (mkIf (cfg.plugins != []) {
+        assertions = [(
+          let
+            hasBadPluginName = p: !(hasPrefix "tmuxplugin" (pluginName p));
+            badPlugins = filter hasBadPluginName cfg.plugins;
+          in
+            {
+              assertion = badPlugins == [];
+              message =
+                "Invalid tmux plugin (not prefixed with \"tmuxplugins\"): "
+                + concatMapStringsSep ", " pluginName badPlugins;
+            }
+        )];
+
+        home.file.".tmux.conf".text = mkAfter ''
+          # ============================================= #
+          # Load plugins with Home Manager                #
+          # --------------------------------------------- #
+
+          ${(concatMapStringsSep "\n\n" (p: ''
+              # ${pluginName p}
+              # ---------------------
+              ${p.extraConfig or ""}
+              run-shell ${
+                if types.package.check p
+                then p.rtp
+                else p.plugin.rtp
+              }
+          '') cfg.plugins)}
+          # ============================================= #
+        '';
+      })
+    ]
+  );
+}