# add the library that runs
add_library(MathFunctions MathFunctions.cxx)

# state that anybody linking to us needs to include the current source dir
# to find MathFunctions.h, while we don't.
target_include_directories(MathFunctions
                           INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
                           )

# should we use our own math functions
option(USE_MYMATH "Use tutorial provided math implementation" ON)
if(USE_MYMATH)

  # does this system provide the log and exp functions?
  include(CheckSymbolExists)
  set(CMAKE_REQUIRED_LIBRARIES "m")
  check_symbol_exists(log "math.h" HAVE_LOG)
  check_symbol_exists(exp "math.h" HAVE_EXP)

  # first we add the executable that generates the table
  add_executable(MakeTable MakeTable.cxx)

  # add the command to generate the source code
  add_custom_command(
    OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/Table.h
    COMMAND MakeTable ${CMAKE_CURRENT_BINARY_DIR}/Table.h
    DEPENDS MakeTable
    )

  # library that just does sqrt
  add_library(SqrtLibrary STATIC
              mysqrt.cxx
              ${CMAKE_CURRENT_BINARY_DIR}/Table.h
              )

  # state that we depend on our binary dir to find Table.h
  target_include_directories(SqrtLibrary PRIVATE
                             ${CMAKE_CURRENT_BINARY_DIR}
                             )

  # state that SqrtLibrary need PIC when the default is shared libraries
  set_target_properties(SqrtLibrary PROPERTIES
                        POSITION_INDEPENDENT_CODE ${BUILD_SHARED_LIBS}
                        )

  target_compile_definitions(MathFunctions PRIVATE "USE_MYMATH")
  if(HAVE_LOG AND HAVE_EXP)
    target_compile_definitions(SqrtLibrary
                               PRIVATE "HAVE_LOG" "HAVE_EXP")
  endif()

  target_link_libraries(MathFunctions PRIVATE SqrtLibrary)
endif()

# define the symbol stating we are using the declspec(dllexport) when
# building on windows
target_compile_definitions(MathFunctions PRIVATE "EXPORTING_MYMATH")

# install rules
install(TARGETS MathFunctions DESTINATION lib)
install(FILES MathFunctions.h DESTINATION include)
