include(GNUInstallDirs)

function(enable_doxygen)
  find_package(Doxygen REQUIRED dot)

  set(DOXYGEN_RECURSIVE              YES)
  set(DOXYGEN_STRIP_FROM_INC_PATH    "include")
  if (WITH_EXAMPLES)
    set(DOXYGEN_EXAMPLE_PATH         "examples/")
    set(DOXYGEN_EXAMPLE_RECURSIVE    YES)
  endif()
  set(DOXYGEN_GENERATE_HTML          YES)
  set(DOXYGEN_HTML_OUTPUT            "doc/html")
  set(DOXYGEN_GENERATE_LATEX         NO)
  set(DOXYGEN_ALLOW_UNICODE_NAMES    YES)
  set(DOXYGEN_BRIEF_MEMBER_DESC      YES)
  set(DOXYGEN_REPEAT_BRIEF           YES)
  set(DOXYGEN_ALWAYS_DETAILED_SEC    YES)
  set(DOXYGEN_INLINE_INHERITED_MEMB  NO)
  set(DOXYGEN_INHERIT_DOCS           YES)
  set(DOXYGEN_SEPARATE_MEMBER_PAGES  NO)
  set(DOXYGEN_TAB_SIZE               4)
  set(DOXYGEN_MARKDOWN_SUPPORT       YES)
  set(DOXYGEN_AUTOLINK_SUPPORT       YES)
  set(DOXYGEN_INLINE_SIMPLE_STRUCTS  NO)
  set(DOXYGEN_QUIET                  YES)
  set(DOXYGEN_WARNINGS               YES)
  set(DOXYGEN_WARN_IF_UNDOCUMENTED   YES)
  set(DOXYGEN_BUILTIN_STL_SUPPORT    YES)
  set(DOXYGEN_VERBATIM_HEADERS       YES)
  set(DOXYGEN_INLINE_SOURCES         YES)
  set(DOXYGEN_SEARCHENGINE           YES)
  set(DOXYGEN_SHOW_FILES             YES)

  file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/doc")

  doxygen_add_docs(${PROJECT_NAME}_doxygen "${ARGV}")
  # Make sure doxygen is run with every build.
  add_custom_target(${PROJECT_NAME}_docs ALL DEPENDS ${PROJECT_NAME}_doxygen)

  install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/doc/html
    DESTINATION "${CMAKE_INSTALL_DOCDIR}")
endfunction()