From b06023bfde04688f19b214707f4741e6240c4d10 Mon Sep 17 00:00:00 2001
From: Ian Chamberlain <ian.h.chamberlain@gmail.com>
Date: Sun, 11 Aug 2024 12:02:42 -0400
Subject: [PATCH] fish: expose session variables package

This allows fish users to source the `hm-session-vars.fish` if they are
not using the generated `config.fish` (which now sources the same file).
---
 modules/programs/fish.nix                     | 36 +++++++++++++------
 tests/modules/programs/fish/default.nix       |  1 +
 .../programs/fish/session-variables.nix       | 26 ++++++++++++++
 .../programs/zsh/session-variables.nix        |  2 +-
 4 files changed, 53 insertions(+), 12 deletions(-)
 create mode 100644 tests/modules/programs/fish/session-variables.nix

diff --git a/modules/programs/fish.nix b/modules/programs/fish.nix
index 02141042d36e..f02d76614db8 100644
--- a/modules/programs/fish.nix
+++ b/modules/programs/fish.nix
@@ -220,15 +220,6 @@ let
       passAsFile = [ "text" ];
     } "env HOME=$(mktemp -d) fish_indent < $textPath > $out";
 
-  translatedSessionVariables =
-    pkgs.runCommandLocal "hm-session-vars.fish" { } ''
-      (echo "function setup_hm_session_vars;"
-      ${pkgs.buildPackages.babelfish}/bin/babelfish \
-      <${config.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
-      echo "end"
-      echo "setup_hm_session_vars") > $out
-    '';
-
 in {
   imports = [
     (mkRemovedOptionModule [ "programs" "fish" "promptInit" ] ''
@@ -393,10 +384,33 @@ in {
         <https://fishshell.com/docs/current/cmds/function.html>.
       '';
     };
+
+    # TODO: maybe this makes more sense as `programs.fish.sessionVariablesPackage`?
+    # if `programs.fish.sessionVariables` were added, would that need its own
+    # separate package, or would they just go in config.fish directly?
+    home.fishSessionVariablesPackage = mkOption {
+      type = types.package;
+      internal = true;
+      description = ''
+        The package containing the {file}`hm-session-vars.fish` file.
+      '';
+    };
   };
 
   config = mkIf cfg.enable (mkMerge [
-    { home.packages = [ cfg.package ]; }
+    {
+      home.fishSessionVariablesPackage =
+        pkgs.runCommandLocal "hm-session-vars.fish" { } ''
+          mkdir -p $out/etc/profile.d
+          (echo "function setup_hm_session_vars;"
+            ${pkgs.buildPackages.babelfish}/bin/babelfish \
+            <${config.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
+            echo "end"
+            echo "setup_hm_session_vars"
+          ) > $out/etc/profile.d/hm-session-vars.fish
+        '';
+
+      home.packages = [ cfg.package config.home.fishSessionVariablesPackage ];
 
     (mkIf cfg.generateCompletions {
       # Support completion for `man` by building a cache for `apropos`.
@@ -473,7 +487,7 @@ in {
         set -q __fish_home_manager_config_sourced; and exit
         set -g __fish_home_manager_config_sourced 1
 
-        source ${translatedSessionVariables}
+        source ${config.home.fishSessionVariablesPackage}/etc/profile.d/hm-session-vars.fish
 
         ${cfg.shellInit}
 
diff --git a/tests/modules/programs/fish/default.nix b/tests/modules/programs/fish/default.nix
index f81ff971ea35..52d53f81ebc3 100644
--- a/tests/modules/programs/fish/default.nix
+++ b/tests/modules/programs/fish/default.nix
@@ -4,4 +4,5 @@
   fish-functions = ./functions.nix;
   fish-no-functions = ./no-functions.nix;
   fish-plugins = ./plugins.nix;
+  fish-session-variables = ./session-variables.nix;
 }
diff --git a/tests/modules/programs/fish/session-variables.nix b/tests/modules/programs/fish/session-variables.nix
new file mode 100644
index 000000000000..bced6d84046d
--- /dev/null
+++ b/tests/modules/programs/fish/session-variables.nix
@@ -0,0 +1,26 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    home.sessionVariables = {
+      V1 = "v1";
+      V2 = "v2-${config.home.sessionVariables.V1}";
+    };
+
+    programs.fish = {
+      enable = true;
+
+      # TODO: should there be an equivalent sessionVariables here like bash + zsh?
+    };
+
+    nmt.script = ''
+      assertFileExists home-path/etc/profile.d/hm-session-vars.fish
+      assertFileRegex home-path/etc/profile.d/hm-session-vars.fish \
+        "set -gx V1 'v1'"
+      assertFileRegex home-path/etc/profile.d/hm-session-vars.fish \
+        "set -gx V1 'v1'"
+    '';
+  };
+}
diff --git a/tests/modules/programs/zsh/session-variables.nix b/tests/modules/programs/zsh/session-variables.nix
index 45c63d236158..53030b4c57c1 100644
--- a/tests/modules/programs/zsh/session-variables.nix
+++ b/tests/modules/programs/zsh/session-variables.nix
@@ -15,7 +15,7 @@
 
     nmt.script = ''
       assertFileExists home-files/.zshenv
-      assertFileRegex home-files/.zshenv 'export V1="v1"'
+      assertFileRegex home-files/.zshenv 'export V1="v2"'
       assertFileRegex home-files/.zshenv 'export V2="v2-v1"'
     '';
   };