treewide: begin restructuring the module tree

modules/plugins/filetree/default.nix

@@ -0,0 +1,5 @@
+{
+  imports = [
+    ./nvimtree
+  ];
+}

modules/plugins/filetree/nvimtree/config.nix

@@ -0,0 +1,85 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit (lib.strings) optionalString;
+  inherit (lib.modules) mkIf mkMerge;
+  inherit (lib.nvim.binds) mkBinding;
+  inherit (lib.nvim.dag) entryAnywhere;
+  inherit (lib.nvim.lua) toLuaObject;
+  # TODO: move this to its own module
+  inherit (lib) pushDownDefault;
+
+  cfg = config.vim.filetree.nvimTree;
+  self = import ./nvimtree.nix {inherit pkgs lib;};
+  inherit (self.options.vim.filetree.nvimTree) mappings;
+in {
+  config = mkIf cfg.enable {
+    vim.startPlugins = ["nvim-tree-lua"];
+
+    vim.maps.normal = mkMerge [
+      (mkBinding cfg.mappings.toggle ":NvimTreeToggle<cr>" mappings.toggle.description)
+      (mkBinding cfg.mappings.refresh ":NvimTreeRefresh<cr>" mappings.refresh.description)
+      (mkBinding cfg.mappings.findFile ":NvimTreeFindFile<cr>" mappings.findFile.description)
+      (mkBinding cfg.mappings.focus ":NvimTreeFocus<cr>" mappings.focus.description)
+    ];
+
+    vim.binds.whichKey.register = pushDownDefault {
+      "<leader>t" = "+NvimTree";
+    };
+
+    vim.luaConfigRC.nvimtreelua = entryAnywhere ''
+      ${
+        optionalString cfg.disableNetrw ''
+          -- disable netrew completely
+          vim.g.loaded_netrw = 1
+          vim.g.loaded_netrwPlugin = 1
+        ''
+      }
+
+      require'nvim-tree'.setup(${toLuaObject cfg.setupOpts})
+
+      ${
+        optionalString cfg.openOnSetup ''
+          -- autostart behaviour
+          -- Open on startup has been deprecated
+          -- see https://github.com/nvim-tree/nvim-tree.lua/wiki/Open-At-Startup
+
+          -- use a nix eval to dynamically insert the open on startup function
+          local function open_nvim_tree(data)
+            local IGNORED_FT = {
+              "markdown",
+            }
+
+            -- buffer is a real file on the disk
+            local real_file = vim.fn.filereadable(data.file) == 1
+
+            -- buffer is a [No Name]
+              local no_name = data.file == "" and vim.bo[data.buf].buftype == ""
+
+            -- &ft
+            local filetype = vim.bo[data.buf].ft
+
+            -- only files please
+            if not real_file and not no_name then
+              return
+            end
+
+            -- skip ignored filetypes
+            if vim.tbl_contains(IGNORED_FT, filetype) then
+              return
+            end
+
+            -- open the tree but don't focus it
+            require("nvim-tree.api").tree.toggle({ focus = false })
+          end
+
+          -- function to automatically open the tree on VimEnter
+          vim.api.nvim_create_autocmd({ "VimEnter" }, { callback = open_nvim_tree })
+        ''
+      }
+    '';
+  };
+}

modules/plugins/filetree/nvimtree/default.nix

@@ -0,0 +1,6 @@
+_: {
+  imports = [
+    ./config.nix
+    ./nvimtree.nix
+  ];
+}