my-nvim-setup/lua/plugins/autocmp/config.lua

return function()
  local cmp = require "cmp"

  cmp.setup {
    snippet = {
      -- Select the luasnip engine here. You can switch to another engine.
      expand = function(args)
        -- vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
        require("luasnip").lsp_expand(args.body) -- For `luasnip` users.
        -- require('snippy').expand_snippet(args.body) -- For `snippy` users.
        -- vim.fn["UltiSnips#Anon"](args.body) -- For `ultisnips` users.
      end,
    },
    window = {
      completion = cmp.config.window.bordered {
        border = "rounded",
        winhighlight = "",
        minwidth = 60,
      },
      documentation = cmp.config.window.bordered {
        border = "rounded",
        winhighlight = "",
      },
    },
    formatting = {
      format = require("lspkind").cmp_format {
        mode = "symbol_text",
      },
    },
    mapping = cmp.mapping.preset.insert {
      ["<C-b>"] = cmp.mapping.scroll_docs(-4),
      ["<C-f>"] = cmp.mapping.scroll_docs(4),
      ["<C-Space>"] = cmp.mapping.complete(),
      ["<C-e>"] = cmp.mapping.abort(),
      ["<CR>"] = cmp.mapping.confirm { select = true }, -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
      ["<Tab>"] = function(fallback)
        if cmp.visible() then
          cmp.select_next_item()
        else
          fallback()
        end
      end,
    },
    sources = cmp.config.sources({
      { name = "nvim_lsp" },
    }, {
      { name = "buffer" },
      { name = "path" },
    }),
  }

  -- `/` cmdline setup.
  cmp.setup.cmdline("/", {
    mapping = cmp.mapping.preset.cmdline(),
    sources = {
      { name = "buffer" },
    },
  })

  -- `:` cmdline setup.
  cmp.setup.cmdline(":", {
    mapping = cmp.mapping.preset.cmdline(),
    sources = cmp.config.sources({
      { name = "path" },
    }, {
      {
        name = "cmdline",
        option = {
          ignore_cmds = { "Man", "!" },
        },
      },
    }),
  })

  -- If you want insert `(` after select function or method item
  local cmp_autopairs = require "nvim-autopairs.completion.cmp"
  cmp.event:on("confirm_done", cmp_autopairs.on_confirm_done())
end