starter/lua/plugins/cmp.lua

-- I've set up a comprehensive completion system using nvim-cmp with the following features:
--
-- 1. Main Completion Sources:
--    - LSP completions (cmp-nvim-lsp)
--    - Snippets (LuaSnip + friendly-snippets)
--    - Buffer words (cmp-buffer)
--    - File paths (cmp-path)
--    - Command line completions (cmp-cmdline)
--
-- 2. Key Mappings:
--    - `<C-n>/<C-p>` - Navigate through completion items
--    - `<C-b>/<C-f>` - Scroll documentation
--    - `<C-Space>` - Trigger completion
--    - `<C-e>` - Close completion window
--    - `<CR>` - Confirm selection
--    - `<S-CR>` - Confirm with replacement
--    - `<Tab>/<S-Tab>` - Navigate completion items or snippets
--
-- 3. Features:
--    - Ghost text preview
--    - Icons for different completion types
--    - Source indicators ([LSP], [Buffer], etc.)
--    - Command-line completion for / ? :
--    - Snippet support with friendly-snippets included
--
-- The configuration is optimized for performance by:
-- - Loading on InsertEnter
-- - Using the latest versions of plugins
-- - Proper lazy loading of snippets

return {
  {
    "hrsh7th/nvim-cmp",
    version = false, -- last release is way too old
    event = "InsertEnter",
    dependencies = {
      "hrsh7th/cmp-nvim-lsp", -- LSP source for nvim-cmp
      "hrsh7th/cmp-buffer", -- Buffer completions
      "hrsh7th/cmp-path", -- Path completions
      "hrsh7th/cmp-cmdline", -- Cmdline completions
      "saadparwaiz1/cmp_luasnip", -- Snippet completions
      {
        "L3MON4D3/LuaSnip",
        version = "v2.*",
        build = "make install_jsregexp",
        dependencies = {
          "rafamadriz/friendly-snippets", -- Preconfigured snippets
        },
      },
    },
    config = function()
      local cmp = require("cmp")
      local luasnip = require("luasnip")

      -- Load friendly-snippets
      require("luasnip.loaders.from_vscode").lazy_load()

      cmp.setup({
        snippet = {
          expand = function(args)
            luasnip.lsp_expand(args.body)
          end,
        },
        completion = {
          completeopt = "menu,menuone,noinsert",
        },
        mapping = cmp.mapping.preset.insert({
          ["<C-n>"] = cmp.mapping.select_next_item({ behavior = cmp.SelectBehavior.Insert }),
          ["<C-p>"] = cmp.mapping.select_prev_item({ behavior = cmp.SelectBehavior.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.
          ["<S-CR>"] = cmp.mapping.confirm({
            behavior = cmp.ConfirmBehavior.Replace,
            select = true,
          }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
          ["<Tab>"] = cmp.mapping(function(fallback)
            if cmp.visible() then
              cmp.select_next_item()
            elseif luasnip.expand_or_jumpable() then
              luasnip.expand_or_jump()
            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" }),
        }),
        sources = cmp.config.sources({
          { name = "nvim_lsp" },
          { name = "luasnip" },
          { name = "buffer" },
          { name = "path" },
        }),
        formatting = {
          format = function(entry, vim_item)
            -- Kind icons
            vim_item.kind = string.format('%s %s', require("user.icons").kinds[vim_item.kind], vim_item.kind)
            -- Source
            vim_item.menu = ({
              buffer = "[Buffer]",
              nvim_lsp = "[LSP]",
              luasnip = "[Snippet]",
              path = "[Path]",
            })[entry.source.name]
            return vim_item
          end
        },
        experimental = {
          ghost_text = true,
        },
      })

      -- Use buffer source for `/` and `?` (if you enabled `native_menu`, this won't work anymore).
      cmp.setup.cmdline({ '/', '?' }, {
        mapping = cmp.mapping.preset.cmdline(),
        sources = {
          { name = 'buffer' }
        }
      })

      -- Use cmdline & path source for ':' (if you enabled `native_menu`, this won't work anymore).
      cmp.setup.cmdline(':', {
        mapping = cmp.mapping.preset.cmdline(),
        sources = cmp.config.sources({
          { name = 'path' }
        }, {
          { name = 'cmdline' }
        })
      })
    end,
  },
}