{ lib, haskellPackages, haskell, removeReferencesTo
# “Plugins” are a fancy way of saying gitit will invoke
# GHC at *runtime*, which in turn makes it pull GHC
# into its runtime closure. Only enable if you really need
# that feature. But if you do you’ll want to use gitit
# as a library anyway.
, pluginSupport ? false
}:

# this is similar to what we do with the pandoc executable

let
  plain = haskellPackages.callPackage ./cabal.nix {};
  plugins =
    if pluginSupport
    then plain
    else haskell.lib.compose.disableCabalFlag "plugins" plain;
  static = haskell.lib.compose.justStaticExecutables plugins;

in
  (haskell.lib.compose.overrideCabal (drv: {
    buildTools = (drv.buildTools or []) ++ [ removeReferencesTo ];
  }) static).overrideAttrs (drv: {

    # These libraries are still referenced, because they generate
    # a `Paths_*` module for figuring out their version.
    # The `Paths_*` module is generated by Cabal, and contains the
    # version, but also paths to e.g. the data directories, which
    # lead to a transitive runtime dependency on the whole GHC distribution.
    # This should ideally be fixed in haskellPackages (or even Cabal),
    # but a minimal gitit is important enough to patch it manually.
    disallowedReferences = [
      haskellPackages.pandoc-types
      haskellPackages.HTTP
      haskellPackages.pandoc
      haskellPackages.happstack-server
      haskellPackages.filestore
    ];
    postInstall = ''
      remove-references-to \
        -t ${haskellPackages.pandoc-types} \
        $out/bin/gitit
      remove-references-to \
        -t ${haskellPackages.HTTP} \
        $out/bin/gitit
      remove-references-to \
        -t ${haskellPackages.pandoc} \
        $out/bin/gitit
      remove-references-to \
        -t ${haskellPackages.happstack-server} \
        $out/bin/gitit
      remove-references-to \
        -t ${haskellPackages.filestore} \
        $out/bin/gitit
    '';

    meta = drv.meta // {
      maintainers = drv.meta.maintainers or []
        ++ [ lib.maintainers.Profpatsch ];
    };
  })