neovim-config/lua/plugins/nvim-cmp.lua

-- Configure nvim-cmp with "supertab"-like behavior for LuaSnip integration: https://www.lazyvim.org/configuration/recipes#supertab
-- Also, prevent autocomplete from automatically selecting the first item in the list on <CR>, and instead require the user to press <Tab> to select the first item.
return {
  "hrsh7th/nvim-cmp",
  dependencies = {
    "hrsh7th/cmp-calc",
    "hrsh7th/cmp-emoji",
    "hrsh7th/cmp-cmdline",
    "petertriho/cmp-git",
  },
  ---@param opts cmp.ConfigSchema
  opts = 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 luasnip = require("luasnip")
    local cmp = require("cmp")

    opts.mapping = vim.tbl_extend("force", opts.mapping, {
      ["<Tab>"] = cmp.mapping(function(fallback)
        -- This bit is for preventing auto-completion auto-triggering from copilot-cmp:
        -- https://github.com/zbirenbaum/copilot-cmp?tab=readme-ov-file#tab-completion-configuration-highly-recommended
        if cmp.visible() and has_words_before() then
          -- You could replace select_next_item() with confirm({ select = true }) to get VS Code autocompletion behavior
          cmp.select_next_item({ behavior = cmp.SelectBehavior.Select })
        -- You could replace the expand_or_jumpable() calls with expand_or_locally_jumpable()
        -- this way you will only jump inside the snippet region
        elseif luasnip.expand_or_jumpable() then
          luasnip.expand_or_jump()
        elseif has_words_before() then
          cmp.complete()
        else
          fallback()
        end
      end, { "i", "s" }),
      ["<S-Tab>"] = cmp.mapping(function(fallback)
        if cmp.visible() then
          cmp.select_prev_item()
        elseif luasnip.jumpable(-1) then
          luasnip.jump(-1)
        else
          fallback()
        end
      end, { "i", "s" }),
      ["<CR>"] = cmp.mapping.confirm({ select = false }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
    })

    -- Do not auto-select the first auto-complete item, require a <Tab> to select the first item.
    opts.completion.completeopt = "menu,menuone,noinsert,noselect"

    opts.sources = cmp.config.sources(vim.list_extend(opts.sources, {
      { name = "emoji" },
      { name = "git" },
      { name = "calc" },
    }))

    -- `/` 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", "!" },
          },
        },
      }),
    })
  end,
}