Enable creation of other config files than init.lua (#246)

wrappers/modules/output.nix

@@ -0,0 +1,134 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+with lib; let
+  pluginWithConfigType = types.submodule {
+    options = {
+      config = mkOption {
+        type = types.lines;
+        description = "vimscript for this plugin to be placed in init.vim";
+        default = "";
+      };
+
+      optional =
+        mkEnableOption "optional"
+        // {
+          description = "Don't load by default (load with :packadd)";
+        };
+
+      plugin = mkOption {
+        type = types.package;
+        description = "vim plugin";
+      };
+    };
+  };
+in {
+  options = {
+    viAlias = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Symlink <command>vi</command> to <command>nvim</command> binary.
+      '';
+    };
+
+    vimAlias = mkOption {
+      type = types.bool;
+      default = false;
+      description = ''
+        Symlink <command>vim</command> to <command>nvim</command> binary.
+      '';
+    };
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.neovim-unwrapped;
+      description = "Neovim to use for nixvim";
+    };
+
+    wrapRc = mkOption {
+      type = types.bool;
+      description = "Should the config be included in the wrapper script";
+      default = false;
+    };
+
+    finalPackage = mkOption {
+      type = types.package;
+      description = "Wrapped neovim";
+      readOnly = true;
+    };
+
+    initContent = mkOption {
+      type = types.str;
+      description = "The content of the init.lua file";
+      readOnly = true;
+      visible = false;
+    };
+  };
+
+  config = let
+    defaultPlugin = {
+      plugin = null;
+      config = "";
+      optional = false;
+    };
+
+    normalizedPlugins = map (x:
+      defaultPlugin
+      // (
+        if x ? plugin
+        then x
+        else {plugin = x;}
+      ))
+    config.extraPlugins;
+
+    neovimConfig = pkgs.neovimUtils.makeNeovimConfig ({
+        inherit (config) viAlias vimAlias;
+        # inherit customRC;
+        plugins = normalizedPlugins;
+      }
+      # Necessary to make sure the runtime path is set properly in NixOS 22.05,
+      # or more generally before the commit:
+      # cda1f8ae468 - neovim: pass packpath via the wrapper
+      // optionalAttrs (functionArgs pkgs.neovimUtils.makeNeovimConfig ? configure) {
+        configure.packages = {
+          nixvim = {
+            start = map (x: x.plugin) normalizedPlugins;
+            opt = [];
+          };
+        };
+      });
+
+    customRC =
+      ''
+        vim.cmd([[
+          ${neovimConfig.neovimRcContent}
+        ]])
+      ''
+      + config.content;
+
+    extraWrapperArgs = builtins.concatStringsSep " " (
+      (optional (config.extraPackages != [])
+        ''--prefix PATH : "${makeBinPath config.extraPackages}"'')
+      ++ (optional (config.wrapRc)
+        ''--add-flags -u --add-flags "${pkgs.writeText "init.lua" customRC}"'')
+    );
+
+    wrappedNeovim = pkgs.wrapNeovimUnstable config.package (neovimConfig
+      // {
+        wrapperArgs = lib.escapeShellArgs neovimConfig.wrapperArgs + " " + extraWrapperArgs;
+        wrapRc = false;
+      });
+  in {
+    type = lib.mkForce "lua";
+    finalPackage = wrappedNeovim;
+    initContent = customRC;
+    extraPlugins =
+      if config.wrapRc
+      then [config.filesPlugin]
+      else [];
+  };
+}