shells: fix a lot of logic and use activation scripts

modules/common/shell/default.nix

@@ -1,16 +1,78 @@
-{ config, lib, ... }: let
-  inherit (lib) attrsToList catAttrs mkConst mkIf mkValue sortOn toInt;
+{ config, lib, pkgs, ... }: let
+  inherit (lib) attrsToList catAttrs concatStringsSep const filter flatten foldl' getAttr getExe head last listToAttrs mapAttrs mapAttrsToList match mkConst mkIf mkValue nameValuePair readFile sortOn splitString toInt unique;
 in {
-  options.shells = mkValue {};
+  environment.shells = config.home-manager.users
+  |> mapAttrsToList (const <| getAttr "shellsByPriority")
+  |> flatten
+  |> unique;
 
-  options.shellsByPriority = mkConst (config.shells
-    |> attrsToList
-    |> sortOn ({ name, ... }: toInt name)
-    |> catAttrs "value");
+  home-manager.sharedModules = [
 
-  config = mkIf config.isDarwin {
-    environment.shells = config.shellsByPriority;
-  };
+  (homeArgs: let
+    config' = homeArgs.config;
+  in {
+    options.shells = mkValue {};
+
+    options.shellsByPriority = mkConst (config'.shells
+      |> attrsToList
+      |> sortOn ({ name, ... }: toInt name)
+      |> catAttrs "value");
+
+    options.variablesMap = mkConst ({
+      HOME = config'.home.homeDirectory;
+      USER = config'.home.username;
+
+      XDG_CACHE_HOME  = config'.xdg.cacheHome;
+      XDG_CONFIG_HOME = config'.xdg.configHome;
+      XDG_DATA_HOME   = config'.xdg.dataHome;
+      XDG_STATE_HOME  = config'.xdg.stateHome;
+    }
+    |> mapAttrsToList (name: value: [
+      { name = "\$${name}"; inherit value; }
+      { name = "\${${name}}"; inherit value; }
+    ])
+    |> flatten
+    |> listToAttrs);
+  })
+
+  (mkIf config.isDarwin (homeArgs: let
+    config' = homeArgs.config;
+
+    homeSessionVariables = let
+      homeSessionVariables = config'.home.sessionVariables;
+
+      homeSessionVariablesExtra = pkgs.runCommand "home-variables-extra.env" {} ''
+          bash -ic '
+            ${config'.variablesMap
+            |> mapAttrsToList (name: value: "export ${name}='${value}'")
+            |> concatStringsSep "\n"}
+
+            alias export=echo
+            source ${config'.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
+          ' > $out
+        ''
+        |> readFile
+        |> splitString "\n"
+        |> filter (s: s != "")
+        |> map (match "([^=]+)=(.*)")
+        |> map (keyAndValue: nameValuePair (head keyAndValue) (last keyAndValue))
+        |> foldl' (x: y: x // y) {};
+
+      homeSessionSearchVariables = config'.home.sessionSearchVariables
+        |> mapAttrs (const <| concatStringsSep ":");
+    in homeSessionVariables
+    // homeSessionVariablesExtra
+    // homeSessionSearchVariables;
+  in {
+    home.file.".zshrc".text = mkIf config.isDarwin /* zsh */ ''
+      ${homeSessionVariables
+      |> mapAttrsToList (name: value: "export ${name}='${value}'")
+      |> concatStringsSep "\n"}
+      SHELL='${getExe <| head config'.shellsByPriority}' exec "$SHELL"
+    '';
+  }))
+
+  ];
 
   # More at modules/linux/shell/default.nix.
   #