From 48949336ff1cc16fd1c388b0136edf554a132215 Mon Sep 17 00:00:00 2001
From: Gabriel Arazas <foodogsquared@foodogsquared.one>
Date: Thu, 20 Mar 2025 08:55:05 +0800
Subject: [PATCH] lib: init XDG-specific subset

This is arguably more suitable for certain environment but Nix ecosystem
is already largely Unix-adjacent anyways.
---
 lib/default.nix       |  2 ++
 lib/xdg.nix           | 31 +++++++++++++++++++++++++++++++
 tests/lib/default.nix |  1 +
 tests/lib/xdg.nix     | 14 ++++++++++++++
 4 files changed, 48 insertions(+)
 create mode 100644 lib/xdg.nix
 create mode 100644 tests/lib/xdg.nix

diff --git a/lib/default.nix b/lib/default.nix
index e3804469..24160a23 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -13,6 +13,7 @@ in pkgs.lib.makeExtensible (self:
     trivial = callLib ./trivial.nix;
     data = callLib ./data.nix;
     math = callLib ./math.nix;
+    xdg = callLib ./xdg.nix;
 
     # For future references, these are the only attributes that are going to be
     # exported as part of nixpkgs overlay.
@@ -43,6 +44,7 @@ in pkgs.lib.makeExtensible (self:
     inherit (self.trivial) countAttrs filterAttrs';
     inherit (self.data) importYAML renderTeraTemplate renderMustacheTemplate;
     inherit (self.fetchers) fetchInternetArchive fetchUgeeDriver;
+    inherit (self.xdg) getXdgDesktop;
   } // lib.optionalAttrs (builtins ? fetchTree) {
     flake = callLib ./flake.nix;
 
diff --git a/lib/xdg.nix b/lib/xdg.nix
new file mode 100644
index 00000000..137cbfa9
--- /dev/null
+++ b/lib/xdg.nix
@@ -0,0 +1,31 @@
+{ pkgs, lib, self }:
+
+rec {
+  /**
+    Naively get the absolute path of a `.desktop` file given a derivation and a
+    name.
+
+    # Arguments
+
+    drv
+    : The derivation.
+
+    name
+    : The name of the `.desktop` file (without the `.desktop` extension).
+
+    # Type
+
+    ```
+    getXdgDesktop :: Derivation -> String -> Path
+    ```
+
+    # Example
+
+    ```nix
+    getXdgDesktop pkgs.wezterm "org.wezfurlong.wezterm"
+    => /nix/store/$HASH-wezterm-org.wezterm.wezterm.desktop
+    ```
+  */
+  getXdgDesktop = drv: name:
+    "${drv}/share/applications/${name}.desktop";
+}
diff --git a/tests/lib/default.nix b/tests/lib/default.nix
index fc32b352..4e1755cd 100644
--- a/tests/lib/default.nix
+++ b/tests/lib/default.nix
@@ -27,6 +27,7 @@ in {
   trivial = callLib ./trivial.nix;
   data = callLib ./data;
   math = callLib ./math.nix;
+  xdg = callLib ./xdg.nix;
 
   # Environment-specific subset.
   home-manager = callLib ./home-manager.nix;
diff --git a/tests/lib/xdg.nix b/tests/lib/xdg.nix
new file mode 100644
index 00000000..da05316a
--- /dev/null
+++ b/tests/lib/xdg.nix
@@ -0,0 +1,14 @@
+{ pkgs, lib, self }:
+
+lib.runTests {
+  testGetXdgDesktop = {
+    expr = self.xdg.getXdgDesktop pkgs.wezterm "org.wezfurlong.wezterm";
+    expected = "${pkgs.wezterm}/share/applications/org.wezfurlong.wezterm.desktop";
+  };
+
+  # This should be a naive function so it should just naively get things.
+  testGetXdgDesktop2 = {
+    expr = self.xdg.getXdgDesktop pkgs.hello "non-existing-desktop";
+    expected = "${pkgs.hello}/share/applications/non-existing-desktop.desktop";
+  };
+}