# Download and configure MinGW compatible MPICH development files for Windows
option(USE_MSMPI "Use Microsoft's MS-MPI SDK instead of MPICH2-1.4.1" OFF)

if(USE_MSMPI)
  message(STATUS "Downloading and configuring MS-MPI 10.1 for Windows cross-compilation")
  set(MPICH2_WIN64_DEVEL_URL "${LAMMPS_THIRDPARTY_URL}/msmpi-win64-devel.tar.gz" CACHE STRING "URL for MS-MPI (win64) tarball")
  set(MPICH2_WIN64_DEVEL_MD5 "86314daf1bffb809f1fcbefb8a547490" CACHE STRING "MD5 checksum of MS-MPI (win64) tarball")
  mark_as_advanced(MPICH2_WIN64_DEVEL_URL)
  mark_as_advanced(MPICH2_WIN64_DEVEL_MD5)

  include(ExternalProject)
  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
    ExternalProject_Add(mpi4win_build
      URL     ${MPICH2_WIN64_DEVEL_URL}
      URL_MD5 ${MPICH2_WIN64_DEVEL_MD5}
      CONFIGURE_COMMAND "" BUILD_COMMAND "" INSTALL_COMMAND ""
      BUILD_BYPRODUCTS <SOURCE_DIR>/lib/libmsmpi.a)
  else()
    message(FATAL_ERROR "Only x86 64-bit builds are supported with MS-MPI")
  endif()

  ExternalProject_get_property(mpi4win_build SOURCE_DIR)
  file(MAKE_DIRECTORY "${SOURCE_DIR}/include")
  add_library(MPI::MPI_CXX UNKNOWN IMPORTED)
  set_target_properties(MPI::MPI_CXX PROPERTIES
    IMPORTED_LOCATION "${SOURCE_DIR}/lib/libmsmpi.a"
    INTERFACE_INCLUDE_DIRECTORIES "${SOURCE_DIR}/include"
    INTERFACE_COMPILE_DEFINITIONS "MPICH_SKIP_MPICXX")
  add_dependencies(MPI::MPI_CXX mpi4win_build)

  # set variables for status reporting at the end of CMake run
  set(MPI_CXX_INCLUDE_PATH "${SOURCE_DIR}/include")
  set(MPI_CXX_COMPILE_DEFINITIONS "MPICH_SKIP_MPICXX")
  set(MPI_CXX_LIBRARIES "${SOURCE_DIR}/lib/libmsmpi.a")
else()
  message(STATUS "Downloading and configuring MPICH2-1.4.1 for Windows cross-compilation")
  set(MPICH2_WIN64_DEVEL_URL "${LAMMPS_THIRDPARTY_URL}/mpich2-win64-devel.tar.gz" CACHE STRING "URL for MPICH2 (win64) tarball")
  set(MPICH2_WIN32_DEVEL_URL "${LAMMPS_THIRDPARTY_URL}/mpich2-win32-devel.tar.gz" CACHE STRING "URL for MPICH2 (win32) tarball")
  set(MPICH2_WIN64_DEVEL_MD5 "4939fdb59d13182fd5dd65211e469f14" CACHE STRING "MD5 checksum of MPICH2 (win64) tarball")
  set(MPICH2_WIN32_DEVEL_MD5 "a61d153500dce44e21b755ee7257e031" CACHE STRING "MD5 checksum of MPICH2 (win32) tarball")
  mark_as_advanced(MPICH2_WIN64_DEVEL_URL)
  mark_as_advanced(MPICH2_WIN32_DEVEL_URL)
  mark_as_advanced(MPICH2_WIN64_DEVEL_MD5)
  mark_as_advanced(MPICH2_WIN32_DEVEL_MD5)

  include(ExternalProject)
  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
    ExternalProject_Add(mpi4win_build
      URL     ${MPICH2_WIN64_DEVEL_URL}
      URL_MD5 ${MPICH2_WIN64_DEVEL_MD5}
      CONFIGURE_COMMAND "" BUILD_COMMAND "" INSTALL_COMMAND ""
      BUILD_BYPRODUCTS <SOURCE_DIR>/lib/libmpi.a)
  else()
    ExternalProject_Add(mpi4win_build
      URL     ${MPICH2_WIN32_DEVEL_URL}
      URL_MD5 ${MPICH2_WIN32_DEVEL_MD5}
      CONFIGURE_COMMAND "" BUILD_COMMAND "" INSTALL_COMMAND ""
      BUILD_BYPRODUCTS <SOURCE_DIR>/lib/libmpi.a)
  endif()

  ExternalProject_get_property(mpi4win_build SOURCE_DIR)
  file(MAKE_DIRECTORY "${SOURCE_DIR}/include")
  add_library(MPI::MPI_CXX UNKNOWN IMPORTED)
  set_target_properties(MPI::MPI_CXX PROPERTIES
    IMPORTED_LOCATION "${SOURCE_DIR}/lib/libmpi.a"
    INTERFACE_INCLUDE_DIRECTORIES "${SOURCE_DIR}/include"
    INTERFACE_COMPILE_DEFINITIONS "MPICH_SKIP_MPICXX")
  add_dependencies(MPI::MPI_CXX mpi4win_build)

  # set variables for status reporting at the end of CMake run
  set(MPI_CXX_INCLUDE_PATH "${SOURCE_DIR}/include")
  set(MPI_CXX_COMPILE_DEFINITIONS "MPICH_SKIP_MPICXX")
  set(MPI_CXX_LIBRARIES "${SOURCE_DIR}/lib/libmpi.a")
endif()