{ stdenv, fetchFromGitHub, ocamlPackages, writeScript
, dune, python3, rsync, buck, watchman, sqlite }:
let
  # Manually set version - the setup script requires
  # hg and git + keeping the .git directory around.
  pyre-version = "0.0.22";  # also change typeshed revision below with $pyre-src/.typeshed-version
  pyre-src = fetchFromGitHub {
    owner = "facebook";
    repo = "pyre-check";
    rev = "v${pyre-version}";
    sha256 = "057vy6zmgwsi0ag9n4m6sszhahmfk2s1ywm36nyfs7w4d0wnk92s";
  };
  versionFile = writeScript "version.ml" ''
    cat > "./version.ml" <<EOF
    open Core
    let build_info () =
    "pyre-nixpkgs ${pyre-version}"
    let version () =
    "${pyre-version}"

    let log_version_banner () =
      Log.info "Running as pid: %d" (Pid.to_int (Unix.getpid ()));
      Log.info "Version: %s" (version ());
      Log.info "Build info: %s" (build_info ())
    EOF
  '';
 pyre-bin = stdenv.mkDerivation {
  name = "pyre-${pyre-version}";

  src = pyre-src;

  buildInputs = with ocamlPackages; [
    ocaml
    findlib
    menhir
    yojson
    core
    sedlex
    ppx_deriving_yojson
    ocamlbuild
    ppxlib
    dune
    ounit
    base64
    sqlite.dev
    # python36Packages.python36Full # TODO
  ];

  preBuild = ''
    # build requires HOME to be set
    export HOME=$TMPDIR

    # "external" because https://github.com/facebook/pyre-check/pull/8/files
    sed "s/%VERSION%/external/" dune.in > dune

    ln -sf ${versionFile} ./scripts/generate-version-number.sh

    mkdir $(pwd)/build
    export OCAMLFIND_DESTDIR=$(pwd)/build
    export OCAMLPATH=$OCAMLPATH:$(pwd)/build
  '';

  buildFlags = [ "release" ];

  doCheck = true;
  # ./scripts/run-python-tests.sh # TODO: once typeshed and python bits are added

  # Note that we're not installing the typeshed yet.
  # Improvement for a future version.
  installPhase = ''
    install -D ./_build/default/main.exe $out/bin/pyre.bin
  '';

  meta = with stdenv.lib; {
    description = "A performant type-checker for Python 3";
    homepage = https://pyre-check.org;
    license = licenses.mit;
    platforms = ocamlPackages.ocaml.meta.platforms;
    maintainers = with maintainers; [ teh ];
  };
};
typeshed = stdenv.mkDerivation {
  pname = "typeshed";
  version = pyre-version;
  src = fetchFromGitHub {
    owner = "python";
    repo = "typeshed";
    rev = "0b49ce75b478fdf283dda5dd1368759ac342dfe2";
    sha256 = "1w5aqbbcfk5ki8n9fgdikkyadjb318ipqyi517s9xnwlzi1jv0fh";
  };
  phases = [ "unpackPhase" "installPhase" ];
  installPhase = "cp -r $src $out";
};
in python3.pkgs.buildPythonApplication {
  pname = "pyre-check";
  version = pyre-version;
  src = pyre-src;
  patches = [ ./pyre-bdist-wheel.patch ];

  # The build-pypi-package script does some funky stuff with build
  # directories - easier to patch it a bit than to replace it
  # completely though:
  postPatch = ''
    mkdir ./build
    substituteInPlace scripts/build-pypi-package.sh \
        --replace 'NIX_BINARY_FILE' '${pyre-bin}/bin/pyre.bin' \
        --replace 'BUILD_ROOT="$(mktemp -d)"' "BUILD_ROOT=$PWD/build"
    for file in client/pyre.py client/commands/initialize.py client/commands/tests/initialize_test.py; do
      substituteInPlace "$file" \
          --replace '"watchman"' '"${watchman}/bin/watchman"'
    done
    substituteInPlace client/buck.py \
        --replace '"buck"' '"${buck}/bin/buck"'
    substituteInPlace client/tests/buck_test.py \
        --replace '"buck"' '"${buck}/bin/buck"'
  '';

  buildInputs = [ pyre-bin ];
  nativeBuildInputs = [ rsync ]; # only required for build-pypi-package.sh
  propagatedBuildInputs = with python3.pkgs; [
    docutils
    typeshed
    click-log
    ipython
    sqlalchemy
    munch
    xxhash
    ujson
  ];
  buildPhase = ''
    bash scripts/build-pypi-package.sh --version ${pyre-version} --bundle-typeshed ${typeshed}
    cp -r build/dist dist
  '';
  checkPhase = ''
    bash scripts/run-python-tests.sh
  '';
}