feat: mapping and options to sort entries in help window (#2482)

* feat: add option to sort entries in help window

* stylua

* Add keymap to toggle sorting methods

* Bug fix

---------

Co-authored-by: Alexander Courtis <alex@courtis.org>

lua/nvim-tree/help.lua

@@ -84,17 +84,29 @@ end
 --- @return number maximum length of text
 local function compute()
   local head_lhs = "nvim-tree mappings"
-  local head_rhs = "exit: q"
+  local head_rhs1 = "exit: q"
+  local head_rhs2 = string.format("sort by %s: s", M.config.sort_by == "key" and "description" or "keymap")
 
   -- formatted lhs and desc from active keymap
   local mappings = vim.tbl_map(function(map)
     return { lhs = tidy_lhs(map.lhs), desc = tidy_desc(map.desc) }
   end, keymap.get_keymap())
 
-  -- sort roughly by lhs
-  table.sort(mappings, function(a, b)
-    return sort_lhs(a.lhs, b.lhs)
-  end)
+  -- sorter function for mappings
+  local sort_fn
+
+  if M.config.sort_by == "desc" then
+    sort_fn = function(a, b)
+      return a.desc:lower() < b.desc:lower()
+    end
+  else
+    -- by default sort roughly by lhs
+    sort_fn = function(a, b)
+      return sort_lhs(a.lhs, b.lhs)
+    end
+  end
+
+  table.sort(mappings, sort_fn)
 
   -- longest lhs and description
   local max_lhs = 0
@@ -105,11 +117,14 @@ local function compute()
   end
 
   -- increase desc if lines are shorter than the header
-  max_desc = math.max(max_desc, #head_lhs + #head_rhs - max_lhs)
+  max_desc = math.max(max_desc, #head_lhs + #head_rhs1 - max_lhs)
 
   -- header, not padded
   local hl = { { "NvimTreeRootFolder", 0, 0, #head_lhs } }
-  local lines = { ("%s%s%s"):format(head_lhs, string.rep(" ", max_desc + max_lhs - #head_lhs - #head_rhs + 2), head_rhs) }
+  local lines = {
+    head_lhs .. string.rep(" ", max_desc + max_lhs - #head_lhs - #head_rhs1 + 2) .. head_rhs1,
+    string.rep(" ", max_desc + max_lhs - #head_rhs2 + 2) .. head_rhs2,
+  }
   local width = #lines[1]
 
   -- mappings, left padded 1
@@ -121,7 +136,7 @@ local function compute()
     width = math.max(#line, width)
 
     -- highlight lhs
-    table.insert(hl, { "NvimTreeFolderName", i, 1, #l.lhs + 1 })
+    table.insert(hl, { "NvimTreeFolderName", i + 1, 1, #l.lhs + 1 })
   end
 
   return lines, hl, width
@@ -175,14 +190,25 @@ local function open()
   vim.wo[M.winnr].winhl = WIN_HL
   vim.wo[M.winnr].cursorline = M.config.cursorline
 
-  -- quit binding
-  vim.keymap.set("n", "q", close, {
-    desc = "nvim-tree: exit help",
-    buffer = M.bufnr,
-    noremap = true,
-    silent = true,
-    nowait = true,
-  })
+  local function toggle_sort()
+    M.config.sort_by = (M.config.sort_by == "desc") and "key" or "desc"
+    open()
+  end
+
+  local keymaps = {
+    q = { fn = close, desc = "nvim-tree: exit help" },
+    s = { fn = toggle_sort, desc = "nvim-tree: toggle sorting method" },
+  }
+
+  for k, v in pairs(keymaps) do
+    vim.keymap.set("n", k, v.fn, {
+      desc = v.desc,
+      buffer = M.bufnr,
+      noremap = true,
+      silent = true,
+      nowait = true,
+    })
+  end
 
   -- close window and delete buffer on leave
   vim.api.nvim_create_autocmd({ "BufLeave", "WinLeave" }, {
@@ -202,6 +228,7 @@ end
 
 function M.setup(opts)
   M.config.cursorline = opts.view.cursorline
+  M.config.sort_by = opts.help.sort_by
 end
 
 return M