{ compiler ? "gcc"
, pkgs ? import <nixpkgs> {} 
, with-mkl ? false
, cuda ? false
, docs ? true
}:

let

  unfree-pkgs = import <nixpkgs> {
    config.allowUnfree = true;
  };

  openblas = import ./etc/nix/openblas.nix { inherit pkgs; }; 

  mkl = import ./etc/nix/mkl.nix { pkgs = unfree-pkgs; };
  cuda-pkg = if cuda then (import ./cuda.nix { pkgs = unfree-pkgs; }) else {};

in

pkgs.mkShell rec {

  compiler-pkg
    = if compiler    == "gcc11" then pkgs.gcc11
    else if compiler == "gcc10" then pkgs.gcc10
    else if compiler == "gcc9" then pkgs.gcc9
    else if compiler == "gcc8" then pkgs.gcc8
    else if compiler == "gcc7" then pkgs.gcc7
    else if compiler == "gcc6" then pkgs.gcc6
    else if compiler == "gcc49" then pkgs.gcc49
    else if compiler == "clang13" then pkgs.clang_13
    else if compiler == "clang12" then pkgs.clang_12
    else if compiler == "clang11" then pkgs.clang_11
    else if compiler == "clang10" then pkgs.clang_10
    else if compiler == "clang9" then pkgs.clang_9
    else if compiler == "clang8" then pkgs.clang_8
    else if compiler == "clang7" then pkgs.clang_7
    else if compiler == "clang6" then pkgs.clang_6
    else if compiler == "clang5" then pkgs.clang_5
    else pkgs.gcc;

  docInputs = with pkgs; [
    emacs
    emacsPackages.ox-rst
    emacsPackages.htmlize

    python3
    python3Packages.breathe

    doxygen
    sphinx

    graphviz
  ];


  buildInputs
    = with pkgs; [

        coreutils
        git vim

        openmpi
        llvmPackages.openmp

        binutils
        emacs
        gfortran

        gnumake
        libtool
        autoconf
        automake
        pkg-config
      ]
    ++ (if with-mkl then mkl.buildInputs else openblas.buildInputs)
    ++ (if docs then docInputs else [])
    ;

  CXX = "${compiler-pkg}/bin/c++";
  CC = "${compiler-pkg}/bin/cc";
  LD = "${compiler-pkg}/bin/ld";

  shellHook
    =
    ''
    export OMPI_CXX=${CXX}
    export OMPI_CC=${CC}
    CXX=${CXX}
    CC=${CC}
    LD=${LD}
    ''
    + (if cuda then cuda-pkg.shellHook else "")
    ;

}