{ lib, pkgs, ... }:

with lib;
let
  out = {
    environment.systemPackages = [
      vim'
    ];

    environment.variables.EDITOR = mkForce "vim";
  };

  runtimepath = concatStringsSep "," [
    vim-industry-colors
    "${pkgs.vim}/share/vim/vim${majmin pkgs.vim.version}"
    "${pkgs.vimPlugins.undotree}/share/vim-plugins/undotree"
  ];

  vim-industry-colors = pkgs.writeTextFile rec {
    name = "vim-industry-colors";
    destination = "/colors/${name}";
    text = ''
      " Vim color file
      " Maintainer:   Shian Lee
      " Last Change:  2014 Mar 6 (for vim 7.4)
      " Remark:       "industry" stands for 'industrial' color scheme. In
      "               industrial HMI (Human-Machine-Interface) programming,
      "               using a standard color scheme is mandatory in many cases
      "               (in traffic-lights for example):
      "
      "   LIGHT_RED is      'Warning'
      "   LIGHT_YELLOW is   'Attention'
      "   LIGHT_GREEN is    'Normal'
      "   LIGHT_MAGENTA is  'Warning-Attention' (light RED-YELLOW)
      "   LIGHT_CYAN is     'Attention-Normal'  (light YELLOW-GREEN).
      "   BLACK is          Dark-High-Contrast Background for maximum safety.
      "   BLUE is           Shade of BLACK (not supposed to get attention).
      "
      "   Industrial color scheme is by nature clear, safe and productive.
      "   Yet, depends on the file type's syntax, it might appear incorrect.

      " Reset to dark background, then reset everything to defaults:
      set background=dark
      highlight clear
      if exists("syntax_on")
          syntax reset
      endif

      let colors_name = "industry"

      hi! Normal ctermfg=White

      " Syntax highlighting
      " (other color-groups using default, see :help group-name):
      hi Comment    cterm=NONE ctermfg=DarkCyan     gui=NONE guifg=#00aaaa
      hi Constant   cterm=NONE ctermfg=LightCyan    gui=NONE guifg=#00ffff
      hi Identifier cterm=NONE ctermfg=LightMagenta gui=NONE guifg=#ff00ff
      hi Function   cterm=NONE ctermfg=LightGreen   gui=NONE guifg=#00ff00
      hi Statement  cterm=NONE ctermfg=White        gui=bold guifg=#ffffff
      hi PreProc    cterm=NONE ctermfg=Yellow       gui=NONE guifg=#ffff00
      hi Type       cterm=NONE ctermfg=LightGreen   gui=bold guifg=#00ff00
      hi Special    cterm=NONE ctermfg=LightRed     gui=NONE guifg=#ff0000
      hi Delimiter  cterm=NONE ctermfg=Yellow       gui=NONE guifg=#ffff00
    '';
  };

  vim' = pkgs.writeScriptBin "vim" ''
    #! /bin/sh
    set -eu
    mkdir -p "$HOME"/.vim/backup
    mkdir -p "$HOME"/.vim/cache
    mkdir -p "$HOME"/.vim/undo
    exec ${pkgs.vim}/bin/vim -u ${vimrc} "$@"
  '';

  vimrc = pkgs.writeText "vimrc" ''
    set nocompatible

    set autoindent
    set backspace=indent,eol,start
    set backup
    set backupdir=$HOME/.vim/backup/
    set directory=$HOME/.vim/cache//
    set hlsearch
    set incsearch
    set mouse=a
    set pastetoggle=<INS>
    set runtimepath=${runtimepath}
    set shortmess+=I
    set showcmd
    set showmatch
    set ttimeoutlen=0
    set undodir=$HOME/.vim/undo
    set undofile
    set undolevels=1000000
    set undoreload=1000000
    set viminfo='20,<1000,s100,h,n$HOME/.vim/cache/info
    set visualbell
    set wildignore+=*.o,*.class,*.hi,*.dyn_hi,*.dyn_o
    set wildmenu
    set wildmode=longest,full

    filetype plugin indent on

    set t_Co=256
    colorscheme industry
    syntax on

    cmap w!! w!sudo tee % >/dev/null

    au BufRead,BufNewFile *.nix so ${pkgs.writeText "nix.vim" ''
      setf nix

      " Ref <nix/src/libexpr/lexer.l>
      syn match INT   /[0-9]\+/
      syn match PATH  /[a-zA-Z0-9\.\_\-\+]*\(\/[a-zA-Z0-9\.\_\-\+]\+\)\+/
      syn match HPATH /\~\(\/[a-zA-Z0-9\.\_\-\+]\+\)\+/
      syn match SPATH /<[a-zA-Z0-9\.\_\-\+]\+\(\/[a-zA-Z0-9\.\_\-\+]\+\)*>/
      syn match URI   /[a-zA-Z][a-zA-Z0-9\+\-\.]*:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']\+/
      hi link INT Constant
      hi link PATH Constant
      hi link HPATH Constant
      hi link SPATH Constant
      hi link URI Constant

      syn match String /"\([^"]\|\\\"\)*"/
      syn match Comment /\s#.*/
    ''}

    nmap <esc>q :buffer
    nmap <M-q> :buffer

    cnoremap <C-A> <Home>

    noremap  <C-c> :q<cr>

    nnoremap <esc>[5^  :tabp<cr>
    nnoremap <esc>[6^  :tabn<cr>
    nnoremap <esc>[5@  :tabm -1<cr>
    nnoremap <esc>[6@  :tabm +1<cr>

    nnoremap <f1> :tabp<cr>
    nnoremap <f2> :tabn<cr>
    inoremap <f1> <esc>:tabp<cr>
    inoremap <f2> <esc>:tabn<cr>

    " <C-{Up,Down,Right,Left>
    noremap <esc>Oa <nop> | noremap! <esc>Oa <nop>
    noremap <esc>Ob <nop> | noremap! <esc>Ob <nop>
    noremap <esc>Oc <nop> | noremap! <esc>Oc <nop>
    noremap <esc>Od <nop> | noremap! <esc>Od <nop>
    " <[C]S-{Up,Down,Right,Left>
    noremap <esc>[a <nop> | noremap! <esc>[a <nop>
    noremap <esc>[b <nop> | noremap! <esc>[b <nop>
    noremap <esc>[c <nop> | noremap! <esc>[c <nop>
    noremap <esc>[d <nop> | noremap! <esc>[d <nop>
    vnoremap u <nop>
  '';

  # "7.4.335" -> "74"
  majmin = x: concatStrings (take 2 (splitString "." x));
in
out
#https://github.com/mbbill/undotree