let
  pkgs = import <nixpkgs> {};
  rootSrc = pkgs.nix-gitignore.gitignoreSource [] ./.;
  baseTask = pkgs.stdenv.mkDerivation {
    name = "dotfiles-task";
    src = rootSrc;
    buildInputs = [];
    phases = "unpackPhase buildPhase";
    buildPhase = ''
      echo "ERROR: base task buildPhase not overriden."
      exit 1
    '';
  };
in with pkgs; with pkgs.stdenv; rec {
  subtasks = rec {
    shellcheck = baseTask.overrideAttrs(baseAttrs: {
      name = "${baseAttrs.name}-shellcheck";
      buildInputs = baseAttrs.buildInputs ++ [ pkgs.shellcheck ];
      buildPhase = ''
        export SHELLCHECK_OPTS="-e SC1090 -e SC1091 -e SC2139"
        ignored='(encrypted|os-installation.sh|notmuch-post.sh)'
        find . -type f -name '*.sh' | grep -E -v $ignored | xargs shellcheck
        touch $out
      '';
    });
    fixme = baseTask.overrideAttrs(baseAttrs:  {
      name = "${baseAttrs.name}-fixme";
      buildInputs = baseAttrs.buildInputs ++ [ ag ];
      buildPhase = ''
        ag FIXME --ignore default.nix || {
          touch $out
        }
      '';
    });
  };
  test = baseTask.overrideAttrs(baseAttrs: rec {
    name = "${baseAttrs.name}-test";
    buildInputs = [
      subtasks.shellcheck
      subtasks.fixme
    ];
    buildPhase = ''
      echo "Ran tests for:"
      for d in ${builtins.toString buildInputs}; do
        echo "  $d"
      done
      echo "All tests passed!"
      touch $out
    '';
  });
}