{ config, lib, pkgs, ... }:

lib.mkIf config.sane.home-manager.enable
{
  # private because there could be sensitive things in the swap
  sane.impermanence.dirs.home.private = [ ".cache/vim-swap" ];

  home-manager.users.colin.programs.neovim = {
    # neovim: https://github.com/neovim/neovim
    enable = true;
    viAlias = true;
    vimAlias = true;
    plugins = with pkgs.vimPlugins; [
      # docs: surround-nvim: https://github.com/ur4ltz/surround.nvim/
      # docs: vim-surround: https://github.com/tpope/vim-surround
      vim-surround
      # docs: fzf-vim (fuzzy finder): https://github.com/junegunn/fzf.vim
      fzf-vim
      # docs: https://github.com/KeitaNakamura/tex-conceal.vim/
      ({
        plugin = tex-conceal-vim;
        type = "viml";
        config = ''
          " present prettier fractions
          let g:tex_conceal_frac=1
        '';
      })
      ({
        plugin = vim-SyntaxRange;
        type = "viml";
        config = ''
          " enable markdown-style codeblock highlighting for tex code
          autocmd BufEnter * call SyntaxRange#Include('```tex', '```', 'tex', 'NonText')
          " autocmd Syntax tex set conceallevel=2
        '';
      })
      # treesitter syntax highlighting: https://nixos.wiki/wiki/Tree_sitters
      # docs: https://github.com/nvim-treesitter/nvim-treesitter
      # config taken from: https://github.com/i077/system/blob/master/modules/home/neovim/default.nix
      # this is required for tree-sitter to even highlight
      ({
        plugin = nvim-treesitter.withAllGrammars;
        type = "lua";
        config = ''
          require'nvim-treesitter.configs'.setup {
            highlight = {
              enable = true,
              -- disable treesitter on Rust so that we can use SyntaxRange
              -- and leverage TeX rendering in rust projects
              disable = { "rust", "tex", "latex" },
              -- disable = { "tex", "latex" },
              -- true to also use builtin vim syntax highlighting when treesitter fails
              additional_vim_regex_highlighting = false
            },
            incremental_selection = {
              enable = true,
              keymaps = {
                init_selection = "gnn",
                node_incremental = "grn",
                mcope_incremental = "grc",
                node_decremental = "grm"
              }
            },
            indent = {
              enable = true,
              disable = {}
            }
          }

          vim.o.foldmethod = 'expr'
          vim.o.foldexpr = 'nvim_treesitter#foldexpr()'
        '';
      })
    ];
    extraConfig = ''
      " let the terminal handle mouse events, that way i get OS-level ctrl+shift+c/etc
      " this used to be default, until <https://github.com/neovim/neovim/pull/19290>
      set mouse=

      " copy/paste to system clipboard
      set clipboard=unnamedplus

      " screw tabs; always expand them into spaces
      set expandtab

      " at least don't open files with sections folded by default
      set nofoldenable

      " allow text substitutions for certain glyphs.
      " higher number = more aggressive substitution (0, 1, 2, 3)
      " i only make use of this for tex, but it's unclear how to
      " apply that *just* to tex and retain the SyntaxRange stuff.
      set conceallevel=2

      " horizontal rule under the active line
      " set cursorline

      " highlight trailing space & related syntax errors (doesn't seem to work??)
      " let c_space_errors=1
      " let python_space_errors=1

      " enable highlighting of leading/trailing spaces,
      " and especially tabs
      " source: https://www.reddit.com/r/neovim/comments/chlmfk/highlight_trailing_whitespaces_in_neovim/
      set list
      set listchars=tab:▷\·,trail:·,extends:◣,precedes:◢,nbsp:○
    '';
  };
}