##################################################################
# Support macro to use a precompiled header
# Usage:
#   use_precompiled_header(TARGET HEADER_FILE SRC_FILE)
#
# PREC will contain the dependency that needs to be linked
# to the project.
##################################################################

IF(CMAKE_COMPILER_IS_GNUCXX)

    EXEC_PROGRAM(
    	${CMAKE_CXX_COMPILER}  
        ARGS 	${CMAKE_CXX_COMPILER_ARG1} -dumpversion 
        OUTPUT_VARIABLE gcc_compiler_version)
    MESSAGE("GCC Version: ${gcc_compiler_version}")
    IF(gcc_compiler_version MATCHES "4\\.[0-9]\\.[0-9]")
        SET(PCHSupport_FOUND TRUE)
    ELSE(gcc_compiler_version MATCHES "4\\.[0-9]\\.[0-9]")
        IF(gcc_compiler_version MATCHES "3\\.4\\.[0-9]")
            SET(PCHSupport_FOUND TRUE)
        ENDIF(gcc_compiler_version MATCHES "3\\.4\\.[0-9]")
    ENDIF(gcc_compiler_version MATCHES "4\\.[0-9]\\.[0-9]")
    
	SET(_PCH_include_prefix "-I")
	
ELSE(CMAKE_COMPILER_IS_GNUCXX)
ENDIF(CMAKE_COMPILER_IS_GNUCXX)

MACRO(_PCH_GET_COMPILE_FLAGS _out_compile_flags)


  STRING(TOUPPER "CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE}" _flags_var_name)
  SET(${_out_compile_flags} ${${_flags_var_name}} )
  
  IF(CMAKE_COMPILER_IS_GNUCXX)
    
    GET_TARGET_PROPERTY(_targetType ${_PCH_current_target} TYPE)
    IF(${_targetType} STREQUAL SHARED_LIBRARY)
      LIST(APPEND ${_out_compile_flags} "${${_out_compile_flags}} -fPIC")
    ENDIF(${_targetType} STREQUAL SHARED_LIBRARY)
    
  ELSE(CMAKE_COMPILER_IS_GNUCXX)
    ## TODO ... ? or does it work out of the box 
  ENDIF(CMAKE_COMPILER_IS_GNUCXX)
  
  GET_DIRECTORY_PROPERTY(DIRINC INCLUDE_DIRECTORIES )
  FOREACH(item ${DIRINC})
    LIST(APPEND ${_out_compile_flags} "${_PCH_include_prefix}${item}")
  ENDFOREACH(item)
  
  GET_DIRECTORY_PROPERTY(_directory_flags DEFINITIONS)
  #MESSAGE("_directory_flags ${_directory_flags}" )
  LIST(APPEND ${_out_compile_flags} ${_directory_flags})
  LIST(APPEND ${_out_compile_flags} ${CMAKE_CXX_FLAGS} )
  
  SEPARATE_ARGUMENTS(${_out_compile_flags})

ENDMACRO(_PCH_GET_COMPILE_FLAGS)


MACRO(_PCH_WRITE_PCHDEP_CXX _targetName _include_file _dephelp)

  SET(${_dephelp} ${CMAKE_CURRENT_BINARY_DIR}/${_targetName}_pch_dephelp.cxx)
  FILE(WRITE  ${${_dephelp}}
"#include \"${_include_file}\" 
int testfunction()
{
    return 0;
}
"
    ) 

ENDMACRO(_PCH_WRITE_PCHDEP_CXX )

MACRO(_PCH_GET_COMPILE_COMMAND out_command _input _output)

	FILE(TO_NATIVE_PATH ${_input} _native_input)
	FILE(TO_NATIVE_PATH ${_output} _native_output)
	

	IF(CMAKE_COMPILER_IS_GNUCXX)
          IF(CMAKE_CXX_COMPILER_ARG1)
	    # remove leading space in compiler argument
            STRING(REGEX REPLACE "^ +" "" pchsupport_compiler_cxx_arg1 ${CMAKE_CXX_COMPILER_ARG1})

	    SET(${out_command} 
	      ${CMAKE_CXX_COMPILER} ${pchsupport_compiler_cxx_arg1} ${_compile_FLAGS}	-x c++-header -o ${_output} ${_input} 
	      )
	  ELSE(CMAKE_CXX_COMPILER_ARG1)
	    SET(${out_command} 
	      ${CMAKE_CXX_COMPILER}  ${_compile_FLAGS}	-x c++-header -o ${_output} ${_input} 
	      )
          ENDIF(CMAKE_CXX_COMPILER_ARG1)
	ELSE(CMAKE_COMPILER_IS_GNUCXX)
		
		SET(_dummy_str "#include <${_input}>")
		FILE(WRITE ${CMAKE_CURRENT_BINARY_DIR}/pch_dummy.cpp ${_dummy_str})
	
		SET(${out_command} 
			${CMAKE_CXX_COMPILER} ${_compile_FLAGS} /c /Fp${_native_output} /Yc${_native_input} pch_dummy.cpp
		)	
		#/out:${_output}

	ENDIF(CMAKE_COMPILER_IS_GNUCXX)
	
ENDMACRO(_PCH_GET_COMPILE_COMMAND )



MACRO(_PCH_GET_TARGET_COMPILE_FLAGS _cflags  _header_name _pch_path _dowarn )

  FILE(TO_NATIVE_PATH ${_pch_path} _native_pch_path)
  message(${_native_pch_path})
  
  IF(CMAKE_COMPILER_IS_GNUCXX)
    # for use with distcc and gcc >4.0.1 if preprocessed files are accessible
    # on all remote machines set
    # PCH_ADDITIONAL_COMPILER_FLAGS to -fpch-preprocess
    # if you want warnings for invalid header files (which is very inconvenient
    # if you have different versions of the headers for different build types
    # you may set _pch_dowarn
    IF (_dowarn)
      SET(${_cflags} "${PCH_ADDITIONAL_COMPILER_FLAGS} -include ${CMAKE_CURRENT_BINARY_DIR}/${_header_name} -Winvalid-pch " )
    ELSE (_dowarn)
      SET(${_cflags} "${PCH_ADDITIONAL_COMPILER_FLAGS} -include ${CMAKE_CURRENT_BINARY_DIR}/${_header_name} " )
    ENDIF (_dowarn)
  ELSE(CMAKE_COMPILER_IS_GNUCXX)
    
    set(${_cflags} "/Fp${_native_pch_path} /Yu${_header_name}" )	
    
  ENDIF(CMAKE_COMPILER_IS_GNUCXX)	
  
ENDMACRO(_PCH_GET_TARGET_COMPILE_FLAGS )

MACRO(GET_PRECOMPILED_HEADER_OUTPUT _targetName _input _output)
  GET_FILENAME_COMPONENT(_name ${_input} NAME)
  GET_FILENAME_COMPONENT(_path ${_input} PATH)
  SET(_output "${CMAKE_CURRENT_BINARY_DIR}/${_name}.gch/${_targetName}_${CMAKE_BUILD_TYPE}.h++")
ENDMACRO(GET_PRECOMPILED_HEADER_OUTPUT _targetName _input)


MACRO(ADD_PRECOMPILED_HEADER_TO_TARGET _targetName _input _pch_output_to_use )
   
  # to do: test whether compiler flags match between target  _targetName
  # and _pch_output_to_use
  GET_FILENAME_COMPONENT(_name ${_input} NAME)

  IF( "${ARGN}" STREQUAL "0")
    SET(_dowarn 0)
  ELSE( "${ARGN}" STREQUAL "0")
    SET(_dowarn 1)
  ENDIF("${ARGN}" STREQUAL "0")


  _PCH_GET_TARGET_COMPILE_FLAGS(_target_cflags ${_name} ${_pch_output_to_use} ${_dowarn})
  #   MESSAGE("Add flags ${_target_cflags} to ${_targetName} " )
  SET_TARGET_PROPERTIES(${_targetName} 
    PROPERTIES	
    COMPILE_FLAGS ${_target_cflags} 
    )

  ADD_CUSTOM_TARGET(pch_Generate_${_targetName}
    DEPENDS	${_pch_output_to_use} 
    )
  
  ADD_DEPENDENCIES(${_targetName} pch_Generate_${_targetName} )
  
ENDMACRO(ADD_PRECOMPILED_HEADER_TO_TARGET)


macro(use_precompiled_header TARGET HEADER_FILE SRC_FILE)
  get_filename_component(HEADER ${HEADER_FILE} NAME)

  if (MSVC)
    set_target_properties(
	    ${TARGET}
	    PROPERTIES COMPILE_FLAGS /Yu"${HEADER}"
	    )
    set_source_files_properties(${SRC_FILE}
      PROPERTIES COMPILE_FLAGS /Yc"${HEADER}"
    )
    
  elseif (CMAKE_COMPILER_IS_GNUCXX)

  SET(_PCH_current_target ${TARGET})
  
  IF(NOT CMAKE_BUILD_TYPE)
    MESSAGE(FATAL_ERROR 
      "This is the ADD_PRECOMPILED_HEADER macro. " 
      "You must set CMAKE_BUILD_TYPE!"
      )
  ENDIF(NOT CMAKE_BUILD_TYPE)

  IF( "${ARGN}" STREQUAL "0")
    SET(_dowarn 0)
  ELSE( "${ARGN}" STREQUAL "0")
    SET(_dowarn 1)
  ENDIF("${ARGN}" STREQUAL "0")


  GET_FILENAME_COMPONENT(_name ${HEADER_FILE} NAME)
  GET_FILENAME_COMPONENT(_path ${HEADER_FILE} PATH)
  GET_PRECOMPILED_HEADER_OUTPUT( ${TARGET} ${HEADER_FILE} _output)
  GET_FILENAME_COMPONENT(_outdir ${_output} PATH )

  GET_TARGET_PROPERTY(_targetType ${_PCH_current_target} TYPE)
   _PCH_WRITE_PCHDEP_CXX(${TARGET} ${HEADER_FILE} _pch_dephelp_cxx)

  IF(${_targetType} STREQUAL SHARED_LIBRARY)
    ADD_LIBRARY(${TARGET}_pch_dephelp SHARED ${_pch_dephelp_cxx} )
  ELSE(${_targetType} STREQUAL SHARED_LIBRARY)
    ADD_LIBRARY(${TARGET}_pch_dephelp STATIC ${_pch_dephelp_cxx})
  ENDIF(${_targetType} STREQUAL SHARED_LIBRARY)

  FILE(MAKE_DIRECTORY ${_outdir})

  
  _PCH_GET_COMPILE_FLAGS(_compile_FLAGS)
  
  #MESSAGE("_compile_FLAGS: ${_compile_FLAGS}")
  #message("COMMAND ${CMAKE_CXX_COMPILER}	${_compile_FLAGS} -x c++-header -o ${_output} ${_input}")
  SET_SOURCE_FILES_PROPERTIES(${CMAKE_CURRENT_BINARY_DIR}/${_name} PROPERTIES GENERATED 1)
  ADD_CUSTOM_COMMAND(
   OUTPUT	${CMAKE_CURRENT_BINARY_DIR}/${_name} 
   COMMAND ${CMAKE_COMMAND} -E copy  ${HEADER_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${_name} # ensure same directory! Required by gcc
   DEPENDS ${HEADER_FILE}
  )
  
  #message("_command  ${_input} ${_output}")
  _PCH_GET_COMPILE_COMMAND(_command  ${CMAKE_CURRENT_BINARY_DIR}/${_name} ${_output} )
  
  #message(${_input} )
  #message("_output ${_output}")

  ADD_CUSTOM_COMMAND(
    OUTPUT ${_output} 	
    COMMAND ${_command}
    DEPENDS ${HEADER_FILE}   ${CMAKE_CURRENT_BINARY_DIR}/${_name} ${TARGET}_pch_dephelp
   )


  ADD_PRECOMPILED_HEADER_TO_TARGET(${TARGET} ${HEADER_FILE}  ${_output} ${_dowarn})

  endif ()
endmacro(use_precompiled_header)

