autoHackage.nix

{ pkgs ? import <nixpkgs> { }
, haskell ? pkgs.haskell
}:

rec {
  cabalHashes = pkgs.fetchFromGitHub {
    owner  = "commercialhaskell";
    repo   = "all-cabal-hashes";
    rev    = "54462f864070cbefd14ab74425da4d4339abbef9";
    sha256 = "1msl4dnj2qksl9rk18jpg5bmclmwbzb1ygmcmx4rl3jrnkfpsgm8";
  };

  stackageLts = pkgs.fetchFromGitHub {
    owner  = "fpco";
    repo   = "lts-haskell";
    rev    = "1a80e0660e630f6dd98f34c3d82c23dc824ada01";
    sha256 = "03f90mklvk8pkc1cvpry4508amacija1alib7qgyzmn4020fh2jf";
  };

  autoHackageSrc = pkgs.stdenv.mkDerivation {
    name = "autoHackage";
    src  = cabalHashes;

    phases = [ "installPhase" ];

    buildInputs = with pkgs; with haskellPackages; [ jq cabal2nix ];

    installPhase = ''
      mkdir -p "$out"
      
      pushd "$src" > /dev/null

      echo "{" > "$out/default.nix"

      # Only build a few just to see
      for package in ab*
      do
        [ -d "$package" ] || continue
        pushd "$package" > /dev/null
        echo -n "$package:"

        firstletter="$(echo "$package" | cut -c 1)"
        mkdir -p "$out/$firstletter"
        packageFile="$out/$firstletter/$package.nix"

        echo "{" > "$packageFile"

        for version in *
        do 
          [ -d "$version" ] || continue
          pushd "$version" > /dev/null
          echo -n " $version"

          success=yes
          hash="$(jq .\"package-hashes\".SHA256 < "$package".json)" || success=no
          cabal2nixOutput="$(cabal2nix . 2>/dev/null)" || success=no

          # cabal2nix --sha256 doesn't seem to do what I think it does
          cabal2nixWithHash="$(echo "$cabal2nixOutput" | sed "s,src = ./.,sha256 = $hash,")"

          if [ "$success" = "yes" ]
          then
            version_="$(echo "$version" | sed s,\\.,_,g)"
            echo "\"v$version_\" = $cabal2nixWithHash;" >> "$packageFile"
          else
            echo -n "←Error"
          fi
            
          popd > /dev/null
        done

        echo "}" >> "$packageFile"

        echo " \"$package\" = import ./$firstletter/$package.nix;" >> "$out/default.nix"

        echo

        popd > /dev/null
      done

      echo "}" >> "$out/default.nix"
      popd > /dev/null
    '';
  };

  autoHackage = import autoHackageSrc;

  test-abstract-deque = pkgs.haskellPackages.callPackage autoHackage.abstract-deque.v0_2_2_1 { };
}