# Running `nix-shell` in the same directory as this file will enter an
# environment in which you can easily hack on or build termonad. It provides:
#  * Termonad's system dependencies.
#  * GHC with all of termonad's haskell dependencies.
#  * Local haddocks for those dependencies.
#  * Hoogle with an index generated from those haddocks.
#  * Cabal.
#  * ghcid.
#  * open-haddock.
#
# In this environment you should be able to e.g.
#  * Build termonad:
#    $ cabal new-build
#  * Open a repl with access to the termonad libraries:
#    $ cabal new-repl
#  * Use `ghcid`:
#    $ ghcid --command='cabal new-repl'
#  * Open local haddocks for e.g. GI.Vte.Objects.Terminal:
#    $ open-haddock GI.Vte.Objects.Terminal
#    or for the gi-gtk package:
#    $ open-haddock gi-gtk
#
# If you pass nix-shell the arguments `--arg indexTermonad true`, then hoogle
# will also index the Termonad libraries, however this will mean the environment
# will need to be rebuilt every time the termonad source changes.

{ compiler ? null, indexTermonad ? false, nixpkgs ? null, additionalOverlays ? [] }:

with (import .nix-helpers/nixpkgs.nix { inherit compiler nixpkgs additionalOverlays; });

let
  # A Haskell package set for a version of GHC that is known working.
  haskPkgSet = termonadKnownWorkingHaskellPkgSet;

  # Nix-shell environment for hacking on termonad.
  termonadEnv = haskPkgSet.termonad.env;

  # Haskell build tools that are nice to have.  It is okay to get these from
  # any Haskell package set, since they do not depend on the GHC version we are
  # using.  We get these from the normal haskellPackages pkg set because then
  # they don't have to be compiled from scratch.
  nativeBuildTools = with haskellPackages; [ cabal-install ghcid ];
in

if indexTermonad
  then
    termonadEnv.overrideAttrs (oldAttrs: {
      nativeBuildInputs =
        let
          ghcEnvWithTermonad =
            haskPkgSet.ghcWithHoogle (hpkgs: [ hpkgs.termonad ]);
        in
        oldAttrs.nativeBuildInputs ++ nativeBuildTools ++ [ ghcEnvWithTermonad ];
    })
  else
    haskPkgSet.shellFor {
      withHoogle = true;
      packages = hpkgs: [ hpkgs.termonad ];
      nativeBuildInputs = termonadEnv.nativeBuildInputs ++ nativeBuildTools;
    }