# If you would like to test and build changes quickly using `cabal`, run:
#
#     $ nix-shell
#     [nix-shell]$ cabal configure --enable-tests && cabal test
#
# This will open up a Nix shell where all of your Haskell tools will work like
# normal, except that all dependencies (including C libraries) are managed by
# Nix.  The only thing that won't work is running tests inside this shell
# (although you can still build them).  Fixing the test suite requires
# extensive patching of the test scripts (see `postPatch` below)
#
# Note that this will compile the library once without tests using Nix.  This
# is due to the fact that `grpc-haskell`'s test suite cannot test code
# generation without the library being built at least once.
#
# If you want to build and test this repository using `nix`, you can run the
# following command:
#
#     $ nix-build --attr grpc-haskell release.nix
#
# ... but this is not recommended for normal development because this will
# rebuild the repository from scratch every time, which is extremely slow.  Only
# do this if you want to exactly reproduce our continuous integration build.
#
# By default, Nix will pick a version for each one of your Haskell dependencies.
# If you would like to select a different version then, run:
#
#     $ cabal2nix cabal://${package-name}-${version} > nix/${package-name}.nix
#
# ... and then add this line below in the Haskell package overrides section:
#
#     ${package-name} =
#       haskellPackagesNew.callPackage ./nix/${package-name}.nix { };
#
# ... replacing `${package-name}` with the name of the package that you would
# like to upgrade and `${version}` with the version you want to upgrade to.
#
# You can also add private Git dependencies in the same way, except supplying
# the `git` URL to clone:
#
#     $ cabal2nix <your private git url>/${package-name}.git > ./nix/${package-name}.nix
#
# ...but also be sure to supply `fetchgit = pkgs.fetchgitPrivate` in the
# `haskellPackagesNew.callPackage` invocation for your private package.
#
# Note that `cabal2nix` also takes an optional `--revision` flag if you want to
# pick a revision other than the latest to depend on.
#
# If you want to test a local source checkout of a dependency, then run:
#
#     $ cabal2nix path/to/dependency/repo > nix/${package-name}.nix
#
# Finally, if you want to add grpc-haskell to your own package set, you can
# setup the overlay with:
#
#     grpc-nixpkgs = import path/to/gRPC-haskell/nixpkgs.nix;
#     grpc-overlay = (import path/to/gRPC-haskell/release.nix).overlay;
#     # optionally use the same nixpkgs source
#     pkgs = grpc-nixpkgs { overlays = [ grpc-overlay ]; };
#
# ... and use the extend function to setup haskell package override:
#
#     # see https://github.com/NixOS/nixpkgs/issues/25887
#     haskellPackages = pkgs.haskellPackages.extend (self: super: {
#       your-package = self.callCabal2nix "your-package" ./. { };
#     };);

let
  nixpkgs = import ./nixpkgs.nix;

  config = {
    allowUnfree = true;
    # For parameterized-0.5.0.0, which we patch for compatbility with
    # proto3-wire-1.2.0 (which also uses the same patch)
    allowBroken = true;
  };

  overlay = pkgsNew: pkgsOld: rec {

    grpc = pkgsNew.callPackage ./nix/grpc.nix { };

    haskellPackages = pkgsOld.haskellPackages.override {
      overrides = haskellPackagesNew: haskellPackagesOld: rec {

        haskell-src =
          haskellPackagesNew.callHackage "haskell-src" "1.0.3.1" {};

        proto3-wire =
          haskellPackagesNew.callPackage ./nix/proto3-wire.nix { };

        proto3-suite =
          pkgsNew.haskell.lib.dontCheck
            (haskellPackagesNew.callPackage ./nix/proto3-suite.nix {});

        grpc-haskell-core =
          pkgsNew.haskell.lib.buildFromSdist (pkgsNew.usesGRPC
            (haskellPackagesNew.callCabal2nix "grpc-haskell-core" ./core {
                 gpr = pkgsNew.grpc;
               }
            )
          );

        grpc-haskell-no-tests =
          pkgsNew.haskell.lib.buildFromSdist (pkgsNew.usesGRPC
            (pkgsNew.haskell.lib.dontCheck
              (haskellPackagesNew.callCabal2nix "grpc-haskell" ./. { })
            ));

        grpc-haskell =
          pkgsNew.usesGRPC
            (pkgsNew.haskell.lib.overrideCabal
              (pkgsNew.haskell.lib.buildFromSdist (haskellPackagesNew.callCabal2nix "grpc-haskell" ./. { }))
              (oldDerivation:
                let
                  ghc =
                    haskellPackagesNew.ghcWithPackages (pkgs: [
                      pkgs.grpc-haskell-no-tests
                    ]);
                  python =
                    pkgsNew.python.withPackages (pkgs: [ pkgs.grpcio-tools ]);

                in rec {
                  configureFlags = (oldDerivation.configureFlags or []) ++ [
                    "--flags=with-examples"
                  ];

                  buildDepends = [
                    pkgsNew.makeWrapper
                  ];

                  patches = [ tests/tests.patch ];

                  postPatch = ''
                    patchShebangs tests
                    substituteInPlace tests/simple-client.sh \
                      --replace @makeWrapper@ ${pkgsNew.makeWrapper} \
                      --replace @grpc@ ${pkgsNew.grpc}
                    substituteInPlace tests/simple-server.sh \
                      --replace @makeWrapper@ ${pkgsNew.makeWrapper} \
                      --replace @grpc@ ${pkgsNew.grpc}
                    wrapProgram tests/protoc.sh \
                      --prefix PATH : ${python}/bin
                    wrapProgram tests/test-client.sh \
                      --prefix PATH : ${python}/bin
                    wrapProgram tests/test-server.sh \
                      --prefix PATH : ${python}/bin
                    wrapProgram tests/simple-client.sh \
                      --prefix PATH : ${ghc}/bin
                    wrapProgram tests/simple-server.sh \
                      --prefix PATH : ${ghc}/bin
                  '';

                  shellHook = (oldDerivation.shellHook or "") + ''
                    # This lets us use our custom ghc and python environments in the shell.
                    export PATH=${ghc}/bin:${python}/bin''${PATH:+:}$PATH
                  '';
                }
            )
            );

        parameterized = pkgsNew.haskell.lib.appendPatch haskellPackagesOld.parameterized ./nix/parameterized.patch;
      };
    };

    protobuf3_2NoCheck =
      pkgsNew.stdenv.lib.overrideDerivation
        pkgsNew.pythonPackages.protobuf
        (oldAttrs : {doCheck = false; doInstallCheck = false;});

    shell-hook-common =
      pkgsNew.lib.optionalString pkgsNew.stdenv.isDarwin ''
        export DYLD_LIBRARY_PATH=${pkgsNew.grpc}/lib''${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH
      '' +
      pkgsNew.lib.optionalString pkgsNew.stdenv.isLinux ''
        export LD_LIBRARY_PATH=${pkgsNew.grpc}/lib''${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH
      '';

    test-grpc-haskell =
      pkgsNew.mkShell {
        nativeBuildInputs = [
          (with pkgsNew.haskellPackages; [
             cabal-install
             (ghcWithPackages (pkgs: with pkgs; [
                grpc-haskell-core
                # No need to guard nix-shell entry on passing package tests
                (pkgsNew.haskell.lib.dontCheck grpc-haskell)
                language-c
                # Additional packages we need to have available for building
                # and running tests in the nix-shell environment
                mmorph pipes tasty tasty-hunit tasty-quickcheck
              ]))
           ])
          (pkgsNew.python.withPackages (pkgs: [ pkgs.grpcio-tools ]))
        ];
        shellHook = ''
          ${shell-hook-common}
          echo Running: cabal configure --extra-include-dirs ${pkgsNew.grpc}/include --extra-lib-dirs ${pkgsNew.grpc}/lib --enable-tests
          cabal configure --extra-include-dirs ${pkgsNew.grpc}/include --extra-lib-dirs ${pkgsNew.grpc}/lib --enable-tests
        '';
      };

    usesGRPC = haskellPackage:
      pkgsNew.haskell.lib.overrideCabal haskellPackage (oldAttributes: {
          preBuild = (oldAttributes.preBuild or "") +
            pkgsNew.lib.optionalString pkgsNew.stdenv.isDarwin ''
              export DYLD_LIBRARY_PATH=${pkgsNew.grpc}/lib''${DYLD_LIBRARY_PATH:+:}$DYLD_LIBRARY_PATH
            '' +
            pkgsNew.lib.optionalString pkgsNew.stdenv.isLinux ''
              export LD_LIBRARY_PATH=${pkgsNew.grpc}/lib''${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH
            '';

          shellHook = (oldAttributes.shellHook or "") + ''
            ${shell-hook-common}
          '';
        }
      );
  };

  overlays = [ overlay ];

in

let
   nixpkgs = import ./nixpkgs.nix;
   linuxPkgs = nixpkgs { inherit config overlays; system = "x86_64-linux" ; };
  darwinPkgs = nixpkgs { inherit config overlays; system = "x86_64-darwin"; };
        pkgs = nixpkgs { inherit config overlays; };

in
  {
    grpc-haskell-core-linux    =  linuxPkgs.haskellPackages.grpc-haskell-core;
    grpc-haskell-core-darwin   = darwinPkgs.haskellPackages.grpc-haskell-core;
    grpc-haskell-core          =       pkgs.haskellPackages.grpc-haskell-core;

    grpc-haskell-linux         =  linuxPkgs.haskellPackages.grpc-haskell;
    grpc-haskell-darwin        = darwinPkgs.haskellPackages.grpc-haskell;
    grpc-haskell               =       pkgs.haskellPackages.grpc-haskell;
    grpc-haskell-no-tests      =       pkgs.haskellPackages.grpc-haskell-no-tests;

    grpc-linux                 =  linuxPkgs.grpc;
    grpc-darwin                = darwinPkgs.grpc;

    grpc                       =       pkgs.grpc;

    overlay                    = overlay;
    inherit (pkgs) test-grpc-haskell;
  }