# This checks HeaderTest's in each module.  A HeaderTest can be found in the
# module 'test' directory in a file itk<module_name>HeaderTest.cxx.  This
# contains a null main(), but includes all the classes in the module.  The
# primary purpose of this test is to make sure there are not missing module
# dependencies.

# Improve performance of MSVC GUI, by reducing number of header tests.
set(MAXIMUM_NUMBER_OF_HEADERS_default 35)
if(MSVC)
  set(MAXIMUM_NUMBER_OF_HEADERS_default 9999)
endif()

# The maximum number of headers in a test.  This helps limit memory issues,
# and the cppcheck tests.  However, if this is not unity, there is a slight
# chance that problems may be hidden.  For a complete header check, set to "1".
set(MAXIMUM_NUMBER_OF_HEADERS ${MAXIMUM_NUMBER_OF_HEADERS_default} CACHE STRING "The number of headers in a HeaderTest code.")
mark_as_advanced(MAXIMUM_NUMBER_OF_HEADERS)

if(NOT TARGET ITKHeaderTests)
  add_custom_target(ITKHeaderTests
    ${CMAKE_COMMAND} --build ${ITK_BINARY_DIR}
    COMMENT "Regenerating and building the header tests.")
endif()

macro(itk_module_headertest _name)
  if(NOT ${_name}_THIRD_PARTY
      AND EXISTS ${${_name}_SOURCE_DIR}/include
      AND Python3_EXECUTABLE
      AND NOT (${_name} STREQUAL ITKTestKernel)
      AND NOT (CMAKE_GENERATOR MATCHES "^Visual Studio 10.*"))

    # Count how many tests we are going to get, and put the source files in
    # the list _outputs.
    # WARNING: This code is highly coupled with the BuildHeaderTest.py file
    # below.  Before making any logic changes here, make sure that script is not
    # effected.
    set(_include ${${_name}_SOURCE_DIR}/include)
    file(GLOB _h_files ${_include}/*.h)
    set(_header_files ${_h_files})
    list(LENGTH _h_files _num_headers)
    set(_outputs ${${_name}_BINARY_DIR}/test/${_name}HeaderTest1.cxx)
    set(_test_num 1)
    set(_available_headers "${MAXIMUM_NUMBER_OF_HEADERS}")
    while(${_num_headers} GREATER ${_available_headers})
      math(EXPR _test_num "${_test_num} + 1")
      math(EXPR _available_headers "${_available_headers} + ${MAXIMUM_NUMBER_OF_HEADERS}")
      list(APPEND _outputs
        ${${_name}_BINARY_DIR}/test/${_name}HeaderTest${_test_num}.cxx)
    endwhile()

    add_custom_target(${_name}HeaderTestClean
      ${CMAKE_COMMAND} -E remove ${_outputs})
    add_dependencies(ITKHeaderTests ${_name}HeaderTestClean)

    # We check to see if the headers are changed.  If so, remove the header test
    # source files so they are regenerated.
    set(_headers_list_md5 "${${_name}_BINARY_DIR}/test/CMakeFiles/HeadersList.md5")
    list(SORT _header_files)
    string(MD5 _new_md5 "${_header_files}")
    set(_regenerate_sources FALSE)
    if(NOT EXISTS "${_headers_list_md5}")
      set(_regenerate_sources TRUE)
    else()
      file(READ "${_headers_list_md5}" _old_md5)
      if(NOT ("${_old_md5}" STREQUAL "${_new_md5}"))
        set(_regenerate_sources TRUE)
      endif()
    endif()
    file(WRITE "${_headers_list_md5}" "${_new_md5}")
    if(${_regenerate_sources})
      file(REMOVE ${_outputs})
    endif()

    set(_test_num 1)
    foreach(_header_test_src ${_outputs})
      get_filename_component(_test_name ${_header_test_src} NAME_WE)
      add_custom_command(
        OUTPUT ${_header_test_src}
        COMMAND ${Python3_EXECUTABLE} ${ITK_CMAKE_DIR}/../Utilities/Maintenance/BuildHeaderTest.py
        ${_name}
        ${${_name}_SOURCE_DIR}
        ${${_name}_BINARY_DIR}
        ${MAXIMUM_NUMBER_OF_HEADERS}
        ${_test_num}
        )
      add_executable(${_test_name} ${_header_test_src})
      target_link_libraries(${_test_name} PUBLIC ${${_name}_LIBRARIES} itksys)

      add_dependencies(${_name}-all ${_test_name})
      math(EXPR _test_num "${_test_num} + 1")
    endforeach()
  endif()
endmacro()
