{ stdenv, fetchgit, fetchFromGitHub
, tcsh, tcl-8_5, fftwSinglePrec }:

stdenv.mkDerivation rec {
  version = "2.11";
  name = "namd-${version}";

  srcs = [
    (fetchgit {
      name = "namd-${version}-src";
      url = "https://charm.cs.illinois.edu/gerrit/namd.git";
      rev = "release-2-11";
      sha256 = "0msxc1zwjsjb5iynm2hzyvk42wrkbaw234kjcmaxv4zvd3wb8qmw";
    })
    (fetchFromGitHub {
      name = "charm-6.7.0-src";
      owner = "UIUC-PPL";
      repo = "charm";
      rev = "v6.7.0";
      sha256 = "0xcw0jnp8l7dkx3cq9qbyyvr8k5zbij7w1ings0xg6ryjmjgi92x";
    })
  ];

  sourceRoot = "namd-${version}-src";
  postUnpack = ''
    chmod -R u+w namd-${version}-src charm-*-src
    mv charm-*-src namd-${version}-src/charm
  '';

#  postUnpack = ''
#    cd namd-${version}
#    tar -xf charm-*.tar
#    tar -xzf fftw-linux-x86_64.tar.gz
#    mv linux-x86_64 fftw
#    tar -xzf tcl*-linux-x86_64.tar.gz
#    mv tcl*-linux-x86_64 tcl
#    tar -xzf tcl*-linux-x86_64-threaded.tar.gz
#    mv tcl*-linux-x86_64-threaded tcl-threaded
#    cd ..
#  '';
  patchPhase = ''
    find charm -type f | xargs sed -i \
      -e 's,/bin/cp,cp,g' \
      -e 's,/bin/rm,rm,g' \
      -e 's,/lib/cpp,cpp,g'
  '';
  configurePhase = ''
    tcsh -f ./config  Linux-x86_64-g++ --charm-arch multicore-linux64 --with-fftw3
  '';
  buildPhase = ''
    cd charm
    ./build charm++ multicore-linux64 --no-build-shared --with-production
    cd ..
    cd Linux-x86_64-g++
    make
    cd ..
  '';
  installPhase = ''
    rm -fr Linux-x86_64-g++/{obj,src,inc,Make*,plugins,sb}
    cp -r plugins Linux-x86_64-g++/
    cp -r psfgen Linux-x86_64-g++/sb
    mkdir -p $out/lib/namd
    cp -r Linux-x86_64-g++/* $out/lib/namd
    mkdir -p $out/bin
    ln -s $out/lib/namd/namd2 $out/bin/namd2
  '';

  buildInputs = [
    tcsh
    tcl-8_5
    fftwSinglePrec
  ];
}