# high-level notes:
#  - wink uses the execjs gem, which needs some javascript runtime
#    to be available. Wink usually uses the mini_racer gem for this,
#    which unfortunately refuses to work on nix, so instead we have
#    to patch it out of wink's dependencies and replace it with 
#    something else
#  - execjs actually just takes any compatible js runtime it can find;
#    this packages uses v8 by default, but you can easily override it
#    with e.g. nodejs and wink should still work.

{ stdenv
, bundlerEnv
, fetchFromGitHub
, zlib
, sqlite
, ruby
, makeWrapper
# v8 may be replaced with e.g. nodejs — see docs for execjs for a list
# of accaptable backends, all of which should all work out of the box
, v8
, ... }:

let
  sources-patched = stdenv.mkDerivation {
    name = "wink-sources-patched";
    
    # wink sources from the c3VOC
    src = fetchFromGitHub {
      owner = "voc";
      repo = "wink";
      rev = "9f1d312b7bf6457fc23aaa9348a43c3900046a6c";
      sha256 = "1xyb4n4ys93mzyj779mdd6ngiials38xfql3ivddxc1l5rk11hbi";
    };
    
    phases = [ "patchPhase" "installPhase" ];
    
    # remove mini_racer and libv8 (its sole dependency) from wink's deps
    patchPhase = ''
      cp -r $src/* .
      sed -i "s/gem 'mini_racer', platforms: :ruby/#removed mini_racer/g" Gemfile
      sed -i "s/mini_racer (0.2.0)/ /g" Gemfile.lock
      sed -i "s/libv8 (>= 6.3)/ /g" Gemfile.lock
    '';
    
    installPhase = ''
      mkdir -p $out
      cp -r * $out/
    '';
  };
  
  # use the patched dependencies to generate derivations for all the
  # ruby dependencies (using a `gemset.nix` generated with bundix)
  gems = bundlerEnv {
    name = "wink-gems";
    inherit ruby;
    gemConfig = {
        nokogiri = attrs: { 
            buildInputs = [ zlib ];
        };
        sqlite3 = attr: {
            buildInputs = [ sqlite ];
        };
    };
    gemfile = sources-patched.outPath + "/Gemfile";
    lockfile = sources-patched.outPath + "/Gemfile.lock";
    
    # Open question: we could generate this dynamically, would that be
    # a good idea?
    gemset = ./gemset.nix;
  };
in
  stdenv.mkDerivation {
    name = "wink-without-wrapping";
    
    src = sources-patched.outPath;
    
    buildInputs = [
      gems
      ruby
      makeWrapper
      v8
    ];
    
    # need to wrap the executables so ruby can find its gems
    installPhase =
      let gempath = "${gems.outPath}/lib/ruby/gems/2.6.0";
      in ''
        mkdir -p $out
        cp -r * $out
        
        makeWrapper $out/bin/rails $out/bin/rails-wrapped --set GEM_PATH ${gempath}
        makeWrapper $out/bin/rake $out/bin/rake-wrapped --set GEM_PATH ${gempath}
      '';
    
  }