Update nvim-ufo config to fix fold close on insert leave

See kevinhwang91/nvim-ufo#7

lua/ucw/keys.lua

@@ -1,4 +1,5 @@
 local map = require('ucw.utils').map
+local actions = require('ucw.keys.actions')
 
 vim.g.mapleader = " "
 
@@ -29,6 +30,9 @@ end, { expr = true })
 map('n', 'gS', [[<cmd>set opfunc=v:lua.require'ucw.keys.actions'.opfunc_textobj_go_start<cr>g@]], opts)
 map('n', 'gE', [[<cmd>set opfunc=v:lua.require'ucw.keys.actions'.opfunc_textobj_go_end<cr>g@]], opts)
 
+-- folding vs lsp
+vim.keymap.set('n', 'K', actions.hoverK, { desc = "Hover over symbol" })
+
 -- For mouse
 map({'n', 'i', 'v'}, '<X2Mouse>', '<c-i>', opts)
 map({'n', 'i', 'v'}, '<X1Mouse>', '<c-o>', opts)

lua/ucw/keys/actions.lua

@@ -74,4 +74,16 @@ function M.opfunc_textobj_go_end()
   vim.cmd 'normal! `]'
 end
 
+-- Invoke fold preview or lsp preview
+function M.hoverK()
+  local winid = nil
+  local ok, ufo = pcall(require, 'ufo')
+  if ok then
+    winid = ufo.peekFoldedLinesUnderCursor()
+  end
+  if not winid then
+    vim.lsp.buf.hover()
+  end
+end
+
 return M

lua/ucw/lsp/init.lua

@@ -48,7 +48,6 @@ local function on_attach(client, bufnr)
       H = { [[<cmd>lua vim.lsp.declaration()<cr>]], "Go to declaration"},
       r = { [[<cmd>Telescope lsp_references<cr>]], "Find references"},
     },
-    K = { '<cmd>lua vim.lsp.buf.hover()<cr>', "Hover over symbol" },
     ['<c-k>'] = { '<cmd>lua vim.diagnostic.open_float()<cr>', "Show diagnostics on the current line" },
     ['<M-S-r>'] = { [[<cmd>lua vim.lsp.buf.rename()<cr>]], "Rename the symbol under cursor" },
   }, { buffer = bufnr })

lua/ucw/units/thirdparty/ufo.lua

@@ -53,6 +53,23 @@ local function ufo_color()
 end
 
 function M.config()
+  -- UFO uses manual folding that unforunately doesn't play well with small foldlevel
+  -- TL'DR is vim will immediately close all folds to foldlevel whenever manual folding
+  -- is updated, which UFO does a lot, notably at InsertLeave.
+  -- See https://github.com/kevinhwang91/nvim-ufo/issues/7
+  vim.opt.foldlevel = 99
+  vim.opt.foldlevelstart = 99  -- useful when switching from a window with small foldlevel
+
+  -- Using ufo provider needs remap 'zR' and 'zM' to not let them change foldlevel
+  vim.keymap.set('n', 'zR', require('ufo').openAllFolds)
+  vim.keymap.set('n', 'zM', require('ufo').closeAllFolds)
+
+  -- Use a command to emulate foldlevel on bufenter
+  -- FUTURE: not possible yet, maybe after neovim#19155
+  -- au.group('ufo-foldlevel-emu', {
+  --   { 'BufEnter', '*', function() end},
+  -- })
+
   -- tell any server that we support foldingRange
   require('ucw.lsp').register_on_server_ready('.*', function(server, opts)
     opts.capabilities = opts.capabilities or vim.lsp.protocol.make_client_capabilities()
@@ -66,7 +83,7 @@ function M.config()
     -- timeout in ms to highlight the range when opening the folded line, 0 to disable
     -- keep this the same as highlight on yank
     open_fold_hl_timeout = 200,
-    fold_virt_text_handler = fold_virt_text_handler
+    fold_virt_text_handler = fold_virt_text_handler,
   }
 
   ufo_color()