nvim: statusline: Enable winbar

Use it to show full path for file. This frees up space in status line
when git branch names are long.

nvim/.config/nvim/after/plugin/statusline.lua

@@ -1,6 +1,5 @@
 local fn  = vim.fn
 local api = vim.api
-local cmd = vim.cmd
 
 local gstatus = { ahead = 0, behind = 0 }
 local update_gstatus = function()
@@ -70,6 +69,7 @@ highlight("DiagnosticsH", colors.orange , colors.bg)
 
 highlight("Location"    , colors.yellow , colors.bg)
 highlight("Progress"    , colors.magenta, colors.bg)
+highlight("WinbarFile"  , colors.magenta, colors.bg)
 
 M.trunc_width = setmetatable({
   git_status = 80,
@@ -146,7 +146,7 @@ M.get_git_status = function(self)
     or ""
 end
 
-M.get_filename = function(self)
+M.get_filename = function()
   local filetype = vim.bo.filetype
   local special_ft = { 'diff', 'fugitive', 'git', 'qf' }
   for _, v in pairs(special_ft) do
@@ -222,8 +222,6 @@ M.set_inactive = function(self)
     -- Putting this in a function like the others seems to not work. And takes
     -- the window number of the active window. Same for filename.
     " %{winnr()}",
-    "%#Filename#",
-    ' %t%m%r',
     self:get_git_branch(),
     "%=",
     self:get_fileformat(),
@@ -238,26 +236,46 @@ _G.Statusline = setmetatable(M, {
   end,
 })
 
-api.nvim_create_augroup("Statusline", {clear = true})
+local status_id = api.nvim_create_augroup("Statusline", {clear = true})
+local hide_status_id = api.nvim_create_augroup("HideStatusline", {clear = true})
+
 api.nvim_create_autocmd({"WinEnter", "BufEnter"}, {
-  group   = "Statusline",
+  group   = status_id,
   pattern = "*",
   command = "setlocal statusline=%!v:lua.Statusline('active')"
 })
 api.nvim_create_autocmd({"WinLeave" , "BufLeave"}, {
-  group   = "Statusline",
+  group   = status_id,
   pattern = "*",
   command = "setlocal statusline=%!v:lua.Statusline('inactive')"
 })
+api.nvim_create_autocmd({"BufWinEnter", "BufFilePost"}, {
+  group    = status_id,
+  callback = function()
+    local winbar_filetype_exclude = {
+      "diff",
+      "fugitive",
+      "git",
+      "help",
+      "packer",
+      "qf"
+    }
 
-api.nvim_create_augroup("HideStatusline", {clear = true})
+    if vim.tbl_contains(winbar_filetype_exclude, vim.bo.filetype) then
+      vim.opt_local.winbar = nil
+      return
+    end
+
+    vim.opt_local.winbar = string.format(" %s%s", "%#WinbarFile#", '%f%m%r')
+  end,
+})
 api.nvim_create_autocmd({"TermOpen", "TermEnter"}, {
-  group   = "HideStatusline",
+  group   = hide_status_id,
   pattern = "*",
   command = "set laststatus=0 noshowmode noruler"
 })
 api.nvim_create_autocmd({"TermLeave"}, {
-  group   = "HideStatusline",
+  group   =  hide_status_id,
   pattern = "*",
   command = "set laststatus=2 showmode ruler"
 })