From 54a9058ee0bba8eddb60183b525150de467243b7 Mon Sep 17 00:00:00 2001
From: Robert Helgesson <robert@rycee.net>
Date: Tue, 17 Oct 2017 15:50:55 +0200
Subject: [PATCH] xdg: add module

When enabled this module will cause Home Manager to manage the user
environment XDG variables. When disabled, then Home Manager will use
the XDG variables taken from the user environment.
---
 modules/default.nix  |   1 +
 modules/misc/xdg.nix | 138 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 modules/misc/xdg.nix

diff --git a/modules/default.nix b/modules/default.nix
index 4cba27ffb..9b6ad758d 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -19,6 +19,7 @@ let
     ./misc/news.nix
     ./misc/nixpkgs.nix
     ./misc/pam.nix
+    ./misc/xdg.nix
     ./programs/bash.nix
     ./programs/beets.nix
     ./programs/browserpass.nix
diff --git a/modules/misc/xdg.nix b/modules/misc/xdg.nix
new file mode 100644
index 000000000..941d51ed8
--- /dev/null
+++ b/modules/misc/xdg.nix
@@ -0,0 +1,138 @@
+{ options, config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.xdg;
+
+  fileType = basePath: (types.loaOf (types.submodule (
+    { name, config, ... }: {
+      options = {
+        target = mkOption {
+          type = types.str;
+          apply = p: "${cfg.configHome}/${p}";
+          description = ''
+            Path to target file relative to <varname>${basePath}</varname>.
+          '';
+        };
+
+        text = mkOption {
+          default = null;
+          type = types.nullOr types.lines;
+          description = "Text of the file.";
+        };
+
+        source = mkOption {
+          type = types.path;
+          description = ''
+            Path of the source file. The file name must not start
+            with a period since Nix will not allow such names in
+            the Nix store.
+            </para><para>
+            This may refer to a directory.
+          '';
+        };
+
+        executable = mkOption {
+          type = types.bool;
+          default = false;
+          description = "Whether the file should be executable.";
+        };
+      };
+
+      config = {
+        target = mkDefault name;
+        source = mkIf (config.text != null) (
+          let
+            file = pkgs.writeTextFile {
+              inherit (config) text executable;
+              name = "user-etc-" + baseNameOf name;
+            };
+          in
+            mkDefault file
+        );
+      };
+    }
+  )));
+
+  defaultCacheHome = "${config.home.homeDirectory}/.cache";
+  defaultConfigHome = "${config.home.homeDirectory}/.config";
+  defaultDataHome = "${config.home.homeDirectory}/.local/share";
+
+  getXdgDir = name: fallback:
+    let
+      value = builtins.getEnv name;
+    in
+      if value != "" then value else fallback;
+
+in
+
+{
+  options.xdg = {
+    enable = mkEnableOption "management of XDG base directories";
+
+    cacheHome = mkOption {
+      type = types.path;
+      defaultText = "~/.cache";
+      description = ''
+        Absolute path to directory holding application caches.
+      '';
+    };
+
+    configFile = mkOption {
+      type = fileType "xdg.configHome";
+      default = {};
+      description = ''
+        Attribute set of files to link into the user's XDG
+        configuration home.
+      '';
+    };
+
+    configHome = mkOption {
+      type = types.path;
+      defaultText = "~/.config";
+      description = ''
+        Absolute path to directory holding application configurations.
+      '';
+    };
+
+    dataHome = mkOption {
+      type = types.path;
+      defaultText = "~/.local/share";
+      description = ''
+        Absolute path to directory holding application data.
+      '';
+    };
+  };
+
+  config = mkMerge [
+    (mkIf cfg.enable {
+      xdg.cacheHome = mkDefault defaultCacheHome;
+      xdg.configHome = mkDefault defaultConfigHome;
+      xdg.dataHome = mkDefault defaultDataHome;
+
+      home.sessionVariables = {
+        XDG_CACHE_HOME = cfg.cacheHome;
+        XDG_CONFIG_HOME = cfg.configHome;
+        XDG_DATA_HOME = cfg.dataHome;
+      };
+    })
+
+    (mkIf (!cfg.enable) {
+      xdg.cacheHome = getXdgDir "XDG_CACHE_HOME" defaultCacheHome;
+      xdg.configHome = getXdgDir "XDG_CONFIG_HOME" defaultConfigHome;
+      xdg.dataHome = getXdgDir "XDG_DATA_HOME" defaultDataHome;
+    })
+
+    {
+      home.file =
+        let
+          f = n: v: {
+            inherit (v) source target;
+            mode = if v.executable then "777" else "444";
+          };
+        in mapAttrsToList f cfg.configFile;
+    }
+  ];
+}