{
  git,
  jq,
  lib,
  nix,
  nvd,
  openssh,
  symlinkJoin,
  writeShellApplication,
  writeTextDir,
  xdg-utils,
}:
let
  bin = writeShellApplication {
    name = "nixfiles";

    runtimeInputs = [
      git
      jq
      nix
      nvd
      openssh
      xdg-utils
    ];

    # Shamelessly appropriated from https://github.com/ncfavier/config.
    # Hopefully Naïm will not sue me for copyright infrigment.
    text = ''
      nixfiles="''${NIXFILES:-.}"
      rebuild="nixos-rebuild"
      rebuild_opts=(--fast --use-remote-sudo)
      cmd=$1
      shift
      case $cmd in
          repl|eval|nix-build|rev)
              args=() flakeArgs=()
              for arg do case $arg in
                  -w|--wip)
                      flakeArgs+=(--override-flake nixfiles "$nixfiles")
                      ;;
                  *)
                      args+=("$arg")
                      ;;
              esac done
              set -- "''${args[@]}"
              ;;&
          compare)
              if command -v xdg-open >/dev/null; then
                open="xdg-open"
              else
                open="open"
              fi
              input=$1
              # shellcheck disable=SC1090
              . <(nix flake metadata --json nixfiles | jq -r --arg open "$open" --arg input "$input" '
                  def browse($url): @sh "$open \($url)";
                  .locks.nodes[$input] |
                  if .locked.type == "github" then
                      browse("https://github.com/\(.locked.owner)/\(.locked.repo)/compare/\(.locked.rev)...\(.original.ref // "master")")
                  elif .locked.type == "gitlab" then
                      browse("https://gitlab.com/\(.locked.owner)/\(.locked.repo)/-/compare/\(.locked.rev)...\(.original.ref // "master")")
                  else
                      "echo unsupported input type \(.locked.type) (supported: github, gitlab)"
                  end
              ')
              ;;
          update)
              if (( $# )); then
                  args=()
                  for input do args+=(--update-input "$input"); done
                  exec nix flake lock --refresh "''${args[@]}" "$nixfiles"
              else
                  # https://github.com/NixOS/nix/issues/6095
                  exec nix flake update -v --refresh "$nixfiles"
              fi
              ;;
          rev)
              if (( $# )); then
                  expr=inputs.''${1//'/'/.inputs.}.rev
              else
                  expr=self.revision
              fi
              nix eval "''${flakeArgs[@]}" -f ~/.nix-defexpr --raw "$expr"
              echo
              ;;
          repl)
              exec nix repl "''${flakeArgs[@]}" -f ~/.nix-defexpr "$@"
              ;;
          eval)
              exec nix eval "''${flakeArgs[@]}" -f ~/.nix-defexpr --json "$@" | jq -r .
              ;;
          nix-build)
              # https://github.com/NixOS/nix/issues/6661
              exec nix-build --log-format bar-with-logs "''${flakeArgs[@]}" ~/.nix-defexpr -A "$@"
              ;;
          specialise)
              name=$1
              shift
              # Assumes that sudo is already configured. Has setuid baked in if needed and etc.
              exec sudo /run/current-system/specialisation/"$name"/bin/switch-to-configuration switch
              ;;
          revert)
              exec sudo /nix/var/nix/profiles/system/bin/switch-to-configuration switch
              ;;
          home)
              attr=nixosConfigurations."$HOSTNAME".config.hm.home.activationPackage
              export VERBOSE=1
              exec nix shell -v ".#$attr" "$@" -c home-manager-generation
              ;;
          diff)
              exec nvd diff /run/current-system "$nixfiles/result"
              ;;
          @*)
              # Assumes that hosts are configured in the OpenSSH configuration.
              host=''${cmd#@}
              hostname=$(ssh -q "$host" 'echo "$HOSTNAME"')
              exec "$rebuild" -v --flake "$nixfiles#$hostname" --target-host "$host" "''${rebuild_opts[@]}" --show-trace "$@"
              ;;
          *)
              exec "$rebuild" -v --flake "$nixfiles" "''${rebuild_opts[@]}" --show-trace "$cmd" "$@"
              ;;
      esac
    '';
  };

  bashCompletion = writeTextDir "/share/bash-completion/completions/nixfiles" ''
    __compreply() {
        local completion
        while IFS= read -r completion; do
            COMPREPLY+=("$completion")
        done < <(compgen "$@" -- "$cur")
    }
    __complete_nix_cmd() {
        local skip=$1
        shift
        COMP_WORDS=("$@" "''${COMP_WORDS[@]:skip}")
        (( COMP_CWORD += $# - skip ))
        _completion_loader nix
        _complete_nix
    }
    _nixfiles() {
        local cur prev words cword
        local nixfiles="''${NIXFILES:-.}"
        _init_completion -n ':=&'
        if [[ "$cword" == 1 ]] || [[ "$cword" == 2 && "$prev" == @* ]]; then
            if [[ $cur == @* ]]; then
                _known_hosts_real -a -- "$cur"
            else
                __compreply -W 'compare update repl eval nix-build specialise revert home boot build build-vm build-vm-with-bootloader dry-activate dry-build edit switch test'
            fi
        else case ''${words[1]} in
            compare|update|rev)
                __complete_nix_cmd "$cword" nix flake lock "$nixfiles" --update-input
                ;;
            repl|eval|nix-build)
                __compreply -W '-w --wip'
                ;;&
            repl)
                __complete_nix_cmd 2 nix repl ~/.nix-defexpr
                ;;
            eval)
                __complete_nix_cmd 2 nix eval -f ~/.nix-defexpr --json
                ;;
            build)
                __complete_nix_cmd 2 nix build -f ~/.nix-defexpr --json
                ;;
            home)
                __complete_nix_cmd 2 nix shell "$nixfiles"
                ;;
            switch)
                __complete_nix_cmd 2 nix build "$nixfiles"
                ;;
        esac fi
    }
    complete -F _nixfiles nixfiles
  '';
in
symlinkJoin {
  name = "nixfiles";

  paths = [
    bin
    bashCompletion
  ];

  meta = with lib; {
    description = "A helper utility to manage NixOS configurations with Nix flakes";
    homepage = "https://git.azahi.cc/nixfiles";
    license = licenses.wtfpl;
    platforms = platforms.unix;
    maintainers = with maintainers; [ azahi ];
    mainProgram = "nixfiles";
  };
}