starter/lua/plugins/nvim-cmp.lua

local supertab = function(opts)
  local has_words_before = function()
    unpack = unpack or table.unpack
    local line, col = unpack(vim.api.nvim_win_get_cursor(0))
    return col ~= 0 and vim.api.nvim_buf_get_lines(0, line - 1, line, true)[1]:sub(col, col):match("%s") == nil
  end

  local cmp = require("cmp")

  local prev = cmp.mapping(function(fallback)
    if cmp.visible() then
      cmp.select_prev_item()
    elseif vim.snippet.active({ direction = -1 }) then
      vim.schedule(function()
        vim.snippet.jump(-1)
      end)
    else
      fallback()
    end
  end, { "i", "s" })

  opts.mapping = vim.tbl_extend("force", opts.mapping, {
    ["<Tab>"] = cmp.mapping(function(fallback)
      if cmp.visible() then
        -- You could replace select_next_item() with confirm({ select = true }) to get VS Code autocompletion behavior
        cmp.select_next_item()
      elseif vim.snippet.active({ direction = 1 }) then
        vim.schedule(function()
          vim.snippet.jump(1)
        end)
      elseif has_words_before() then
        cmp.complete()
      else
        fallback()
      end
    end, { "i", "s" }),
    ["<S-Tab>"] = prev,
    ["<C-Tab>"] = prev,
  })
end

local function format(opts)
  -- Set custom formatting to add padding
  opts.formatting = {
    format = function(entry, vim_item)
      -- vim_item.abbr = " " .. vim_item.abbr .. " " -- Add padding
      return vim_item
    end,
  }

  -- Set custom window options
  opts.window = {
    completion = require("cmp").config.window.bordered(),
    documentation = require("cmp").config.window.bordered(),
  }
end

return {
  {
    "hrsh7th/nvim-cmp",
    opts = function(_, opts)
      supertab(opts)
      format(opts)
    end,
  },
}