dotfiles/config/nvim/lua/plugins/ufo.lua

-- Not UFO in the sky, but an ultra fold in Neovim.
-- https://github.com/kevinhwang91/nvim-ufo
return {
  "kevinhwang91/nvim-ufo",
  dependencies = "kevinhwang91/promise-async",
  config = function()
    vim.o.fillchars = [[eob: ,fold: ,foldopen:,foldsep: ,foldclose:]]
    vim.o.foldcolumn = "0"
    vim.o.foldlevel = 99
    vim.o.foldlevelstart = 100
    vim.o.foldenable = true

    local handler = function(virtText, lnum, endLnum, width, truncate)
      local newVirtText = {}
      local suffix = (" 󰁂 %d "):format(endLnum - lnum)
      local sufWidth = vim.fn.strdisplaywidth(suffix)
      local targetWidth = width - sufWidth
      local curWidth = 0
      for _, chunk in ipairs(virtText) do
        local chunkText = chunk[1]
        local chunkWidth = vim.fn.strdisplaywidth(chunkText)
        if targetWidth > curWidth + chunkWidth then
          table.insert(newVirtText, chunk)
        else
          chunkText = truncate(chunkText, targetWidth - curWidth)
          local hlGroup = chunk[2]
          table.insert(newVirtText, { chunkText, hlGroup })
          chunkWidth = vim.fn.strdisplaywidth(chunkText)
          if curWidth + chunkWidth < targetWidth then
            suffix = suffix .. (" "):rep(targetWidth - curWidth - chunkWidth)
          end
          break
        end
        curWidth = curWidth + chunkWidth
      end
      table.insert(newVirtText, { suffix, "MoreMsg" })
      return newVirtText
    end

    require("ufo").setup({
      fold_virt_text_handler = handler,
      close_fold_kinds_for_ft = {
        default = { "imports", "comment" },
      },
      open_fold_hl_timeout = 300,
      enable_get_fold_virt_text = false,
      preview = {},
      provider_selector = function()
        return { "lsp", "indent" }
      end,
    })
  end,
  keys = {
    {
      "zR",
      function()
        require("ufo").openAllFolds()
      end,
      desc = "Open all folds",
    },
    {
      "zM",
      function()
        require("ufo").closeAllFolds()
      end,
      desc = "Close all folds",
    },
    {
      "zK",
      function()
        local winid = require("ufo").peekFoldedLinesUnderCursor()
        if not winid then
          vim.lsp.buf.hover()
        end
      end,
      desc = "Peek fold",
    },
  },
}