class Mpich < Formula
  desc "Implementation of the MPI Message Passing Interface standard"
  homepage "https://www.mpich.org/"
  url "https://www.mpich.org/static/downloads/3.3.1/mpich-3.3.1.tar.gz"
  mirror "https://fossies.org/linux/misc/mpich-3.3.1.tar.gz"
  sha256 "fe551ef29c8eea8978f679484441ed8bb1d943f6ad25b63c235d4b9243d551e5"

  bottle do
    cellar :any
    sha256 "b672d8eb887747734308c4b3f08f683a48e8a68764e163d6b09d1dfa2b314b9b" => :catalina
    sha256 "4483dc34e84b9aea1ed7ffbf84145a62d59dd3b319eefed12ed92fffbb559389" => :mojave
    sha256 "aba87dc0cbb581fc52cdb1462ed6a2b32c56cbebbd59a682da884a22f437b7b5" => :high_sierra
    sha256 "b64674c00c36b6bd9ba9f177f53f33c6f5f6d5c107f9069a7a5f558cfddb3499" => :sierra
  end

  head do
    url "https://github.com/pmodels/mpich.git"

    depends_on "autoconf" => :build
    depends_on "automake" => :build
    depends_on "libtool"  => :build
  end

  depends_on "gcc" # for gfortran

  conflicts_with "open-mpi", :because => "both install MPI compiler wrappers"

  def install
    if build.head?
      # ensure that the consistent set of autotools built by homebrew is used to
      # build MPICH, otherwise very bizarre build errors can occur
      ENV["MPICH_AUTOTOOLS_DIR"] = HOMEBREW_PREFIX + "bin"
      system "./autogen.sh"
    end

    system "./configure", "--disable-dependency-tracking",
                          "--disable-silent-rules",
                          "--prefix=#{prefix}",
                          "--mandir=#{man}"

    system "make"
    system "make", "check"
    system "make", "install"
  end

  test do
    (testpath/"hello.c").write <<~EOS
      #include <mpi.h>
      #include <stdio.h>

      int main()
      {
        int size, rank, nameLen;
        char name[MPI_MAX_PROCESSOR_NAME];
        MPI_Init(NULL, NULL);
        MPI_Comm_size(MPI_COMM_WORLD, &size);
        MPI_Comm_rank(MPI_COMM_WORLD, &rank);
        MPI_Get_processor_name(name, &nameLen);
        printf("[%d/%d] Hello, world! My name is %s.\\n", rank, size, name);
        MPI_Finalize();
        return 0;
      }
    EOS
    system "#{bin}/mpicc", "hello.c", "-o", "hello"
    system "./hello"
    system "#{bin}/mpirun", "-np", "4", "./hello"

    (testpath/"hellof.f90").write <<~EOS
      program hello
      include 'mpif.h'
      integer rank, size, ierror, tag, status(MPI_STATUS_SIZE)
      call MPI_INIT(ierror)
      call MPI_COMM_SIZE(MPI_COMM_WORLD, size, ierror)
      call MPI_COMM_RANK(MPI_COMM_WORLD, rank, ierror)
      print*, 'node', rank, ': Hello Fortran world'
      call MPI_FINALIZE(ierror)
      end
    EOS
    system "#{bin}/mpif90", "hellof.f90", "-o", "hellof"
    system "./hellof"
    system "#{bin}/mpirun", "-np", "4", "./hellof"
  end
end