{
  programs ={
    fish = {
      enable = true;
      generateCompletions = true;

      interactiveShellInit = ''
        set fish_greeting # disable greeting

        complete -c nixos -f

        # autocomplete for `nixos` command
        complete -c nixos \
          -n "__fish_use_subcommand" \
          -a "update" \
          -d "Update system using nh"

        complete -c nixos \
          -n "__fish_use_subcommand" \
          -a "upgrade" \
          -d "Upgrade system using nh"

        complete -c nixos \
          -n "__fish_use_subcommand" \
          -a "config" \
          -d "Edit nix config file"

        complete -c nixos \
          -n "__fish_use_subcommand" \
          -a "clean" \
          -d "Clean nix store"

        # make `nixos config` autocomplete based on $HOME/.nix
        complete -c nixos \
          -n "__fish_seen_subcommand_from config" \
          -a "(__fish_nixos_config_files)" \
          -f
      '';

      shellAliases = {
        ls = "eza --icons=always --color=always";
        ll = "eza -a  --long --icons=always --color=always --no-time";
        lt = "eza -a  --long --tree --icons=always --color=always --no-time";

        cat = "bat";

        grep = "grep --color=auto";

        mv = "mv -i";
        cp = "cp -i";
        rm = "rm -i";

        fetch = "nix run nixpkgs#pfetch";
      };

      shellInitLast = '''';

      functions = {
        __fish_nixos_config_files = ''
          # Only show directories and files inside ~/.nix
          set base "$HOME/.nix"

          for f in (command find $base \
            \( -type d -name .git -prune \) -o \
            -type f -print 2>/dev/null)

            if string match -rq '\.(otf|ttf|svg|png|jpg)$' -- $f
              continue
            end
            echo $f
          end | while read -l f
            set rel (string replace -r "^$base/" "" $f)
            echo $rel
          end
        '';

        nixos = ''
          set defaultResponse "Usage: nixos update | up || nixos upgrade || nixos config <path> || nixos clean" 
          if test (count $argv) -lt 1
            echo defaultResponse
            return 1
          end

          switch $argv[1]
            case update up
              if test (count $argv) -gt 1
                echo "Error: 'nixos update' takes no additional arguments."
                return 1
              end
              nh os switch $HOME/.nix
            case upgrade
              if test (count $argv) -gt 1
                echo "Error: 'nixos upgrade' takes no additional arguments."
                return 1
              end
              nh os switch $HOME/.nix -u --ask
            case config
              if test (count $argv) -lt 2
                echo "Error: 'nixos config' requires a <path> argument (relative to $HOME/.nix)"
                return 1
              end
              hx ~/.nix/$argv[2]
            case clean
              if test (count $argv) -gt 1
                echo "Error: 'nixos clean' takes no additional arguments."
                return 1
              end
              nh clean all --verbose
            case '*'
              echo defaultResponse
              return 1
          end
        '';

        nix = ''
          if test $argv[1] = develop
            set -l flake
            if test (count $argv) -lt 2
              echo "Usage: nix develop <python|nim|js|flake> [..]"
              return 1
            end

            switch $argv[2]
              case python
                set flake $HOME/.nix#python
                set argv $argv[3..-1]
              case js
                set flake $HOME/.nix#js
                set argv $argv[3..-1]
              case python
                set flake $HOME/.nix#nim
                set argv $argv[3..-1]
              case '*'
                set flake $argv[2]
                set argv $argv[3..-1]
            end
            command nix develop $flake -c fish
          else
            command nix $argv
          end
        '';
      };
    };

    starship = {
      enable = true;
    };

    atuin = {
      enable = true;
      enableFishIntegration = true;
    };
  };
}