Revert "feat(vim): remove nerd-tree"

This reverts commit 9acbbc65b30a2a08e19bf6fe4e0e3b07e1e71c44.

.vimrc

@@ -145,6 +145,7 @@ nmap <Leader>fb :Buffers<CR>
 nmap <Leader>fg :Rg ""<CR>
 nmap <expr> <Leader>fe &filetype ==# 'netrw' ? ':Rex<CR>' : ':Ex<CR>'
 nmap <C-w>q :bn \| bd#<CR>
+nmap <Leader>tt :NERDTreeToggle<CR>
 nmap <Leader>uu :tabnew \| bprevious \| UndotreeToggle \| UndotreeFocus<CR>
 tnoremap <Esc> <C-\><C-n>
 tnoremap <C-\> <Esc>
@@ -214,6 +215,20 @@ let g:gitgutter_sign_removed = '┃'
 
 let g:colorizer_colornames = 0
 
+" {{{3 NERDTree
+
+let g:NERDTreeDirArrowCollapsible = ""
+let g:NERDTreeDirArrowExpandable = ""
+let g:NERDTreeHijackNetrw = 0
+let g:NERDTreeShowHidden = 1
+let g:NERDTreeWinSize = 40
+let g:NERDTreeMinimalUI = 1
+let g:NERDTreeCascadeSingleChildDir = 0
+let g:NERDTreeRemoveFileCmd = "gio trash "
+let g:NERDTreeRemoveDirCmd = "gio trash "
+let g:NERDTreeMapActivateNode = "l"
+let g:NERDTreeMapCloseDir = "h"
+
 " {{{3 onedark
 let g:onedark_color_overrides = {
             \ "background": {"gui": "#1f2329", "cterm": "235", "cterm16": "NONE" },
@@ -277,6 +292,8 @@ call plug#begin(s:plug_dir)
     Plug 'rbong/vim-flog'
     Plug 'chrisbra/Colorizer'
     Plug 'jceb/vim-orgmode'
+    Plug 'preservim/nerdtree'
+    Plug 'ryanoasis/vim-devicons'
     Plug 'mbbill/undotree'
 
     " Plug 'prabirshrestha/vim-lsp'
@@ -678,7 +695,25 @@ function! ToggleGitStatus()
     call OpenGitStatus()
 endfunction
 
+function! s:SetupNERDTree()
+    if !exists('g:loaded_nerd_tree')
+        return
+    endif
+
+    " Exit Vim if NERDTree is the only window remaining in the only tab.
+    autocmd BufEnter * if tabpagenr('$') == 1 &&
+                \ winnr('$') == 1 &&
+                \ exists('b:NERDTree') &&
+                \ b:NERDTree.isTabTree() |
+                \ quit |
+                \ endif
+
+    " Start NERDTree and put the cursor back in the other window.
+    NERDTree | wincmd p
+endfunction
+
 autocmd VimEnter * call s:SetupGitGutter()
+autocmd VimEnter * call s:SetupNERDTree()
 
 cnoreabbrev term terminal ++curwin