feat: add venn.nvim for drawing venn diagrams

modules/lib/types-plugin.nix

@@ -49,6 +49,7 @@ with lib; let
     "cinnamon-nvim"
     "cheatsheet-nvim"
     "colorizer"
+    "venn-nvim"
   ];
 
   pluginsType = with types; listOf (nullOr (either (enum availablePlugins) package));

modules/utility/default.nix

@@ -1,5 +1,6 @@
 _: {
   imports = [
     ./colorizer.nix
+    ./venn.nix
   ];
 }

modules/utility/venn.nix

@@ -0,0 +1,47 @@
+{
+  pkgs,
+  config,
+  lib,
+  ...
+}:
+with lib;
+with builtins; let
+  cfg = config.vim.utility.venn-nvim;
+in {
+  options.vim.utility.venn-nvim = {
+    enable = mkEnableOption "draw ASCII diagrams in Neovim";
+  };
+
+  config = mkIf (cfg.enable) {
+    vim.startPlugins = [
+      "venn-nvim"
+    ];
+
+    # TODO: https://github.com/jbyuki/venn.nvim#using-toggle-command
+    # add keybindings for drawing diagrams4
+    vim.luaConfigRC.venn-nvim = nvim.dag.entryAnywhere ''
+      local venn = require('venn')
+      -- venn.nvim: enable or disable keymappings
+      function _G.Toggle_venn()
+          local venn_enabled = vim.inspect(vim.b.venn_enabled)
+          if venn_enabled == "nil" then
+              vim.b.venn_enabled = true
+              vim.cmd[[setlocal ve=all]]
+              -- draw a line on HJKL keystokes
+              vim.api.nvim_buf_set_keymap(0, "n", "J", "<C-v>j:VBox<CR>", {noremap = true})
+              vim.api.nvim_buf_set_keymap(0, "n", "K", "<C-v>k:VBox<CR>", {noremap = true})
+              vim.api.nvim_buf_set_keymap(0, "n", "L", "<C-v>l:VBox<CR>", {noremap = true})
+              vim.api.nvim_buf_set_keymap(0, "n", "H", "<C-v>h:VBox<CR>", {noremap = true})
+              -- draw a box by pressing "f" with visual selection
+              vim.api.nvim_buf_set_keymap(0, "v", "f", ":VBox<CR>", {noremap = true})
+          else
+              vim.cmd[[setlocal ve=]]
+              vim.cmd[[mapclear <buffer>]]
+              vim.b.venn_enabled = nil
+          end
+      end
+      -- toggle keymappings for venn using <leader>v
+      vim.api.nvim_set_keymap('n', '<leader>v', ":lua Toggle_venn()<CR>", { noremap = true})
+    '';
+  };
+}