# first we can indicate the documentation build as an option and set it to ON by default
option(BUILD_DOC "Build documentation" ON)

# check if Doxygen is installed
find_package(Doxygen)
if (DOXYGEN_FOUND)
    # set input and output files
    set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in)
    set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)

    # request to configure the file
    configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
    message("Doxygen build started")

    # note the option ALL which allows to build the docs together with the application
    add_custom_target( doc_doxygen ALL
        COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
        COMMENT "Generating API documentation with Doxygen"
        VERBATIM )

    install(DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/api"
        DESTINATION doc
    )
  
else (DOXYGEN_FOUND)
  message(STATUS "Doxygen need to be installed to generate the doxygen documentation. To install type common `sudo apt install -y doxygen texlive-latex-base graphviz` ")
endif (DOXYGEN_FOUND)