neovim-flake/modules/completion/default.nix

{
  pkgs,
  lib,
  config,
  ...
}:
with lib;
with builtins; let
  cfg = config.vim.autocomplete;
in {
  options.vim = {
    autocomplete = {
      enable = mkOption {
        type = types.bool;
        default = false;
        description = "enable autocomplete";
      };

      type = mkOption {
        type = types.enum ["nvim-cmp"];
        default = "nvim-cmp";
        description = "Set the autocomplete plugin. Options: [nvim-cmp]";
      };
    };
  };

  config = mkIf cfg.enable {
    vim.startPlugins = [
      "nvim-cmp"
      "cmp-buffer"
      "cmp-vsnip"
      "cmp-path"
      "cmp-treesitter"
    ];

    vim.luaConfigRC.completion = mkIf (cfg.type == "nvim-cmp") (nvim.dag.entryAnywhere ''
      local has_words_before = function()
        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 feedkey = function(key, mode)
        vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes(key, true, true, true), mode, true)
      end

      local cmp = require'cmp'
      cmp.setup({
        snippet = {
          expand = function(args)
            vim.fn["vsnip#anonymous"](args.body)
          end,
        },
        sources = {
          ${optionalString (config.vim.lsp.enable) "{ name = 'nvim_lsp' },"}
          ${optionalString (config.vim.lsp.rust.enable) "{ name = 'crates' },"}
          { name = 'vsnip' },
          { name = 'treesitter' },
          { name = 'path' },
          { name = 'buffer' },
        },
        mapping = {
          ['<C-d>'] = cmp.mapping(cmp.mapping.scroll_docs(-4), { 'i', 'c' }),
          ['<C-f>'] = cmp.mapping(cmp.mapping.scroll_docs(4), { 'i', 'c'}),
          ['<C-Space>'] = cmp.mapping(cmp.mapping.complete(), { 'i', 'c'}),
          ['<C-y>'] = cmp.config.disable,
          ['<C-e>'] = cmp.mapping({
            i = cmp.mapping.abort(),
            c = cmp.mapping.close(),
          }),
          ['<CR>'] = cmp.mapping.confirm({
            select = true,
          }),
          ['<Tab>'] = cmp.mapping(function (fallback)
            if cmp.visible() then
              cmp.select_next_item()
            elseif vim.fn['vsnip#available'](1) == 1 then
              feedkey("<Plug>(vsnip-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 vim.fn['vsnip#available'](-1) == 1 then
              feedkeys("<Plug>(vsnip-jump-prev)", "")
            end
          end, { 'i', 's' })
        },
        completion = {
          completeopt = 'menu,menuone,noinsert',
        },
        formatting = {
          format = function(entry, vim_item)
            -- type of kind
            vim_item.kind = ${
        optionalString (config.vim.visuals.lspkind.enable)
        "require('lspkind').presets.default[vim_item.kind] .. ' ' .."
      } vim_item.kind

            -- name for each source
            vim_item.menu = ({
              buffer = "[Buffer]",
              nvim_lsp = "[LSP]",
              vsnip = "[VSnip]",
              crates = "[Crates]",
              path = "[Path]",
            })[entry.source.name]
            return vim_item
          end,
        }
      })
      ${optionalString (config.vim.autopairs.enable && config.vim.autopairs.type == "nvim-autopairs") ''
        local cmp_autopairs = require('nvim-autopairs.completion.cmp')
        cmp.event:on('confirm_done', cmp_autopairs.on_confirm_done({ map_char = { text = ""} }))
      ''}
    '');

    vim.snippets.vsnip.enable =
      if (cfg.type == "nvim-cmp")
      then true
      else config.vim.snippets.vsnip.enable;
  };
}