option(MYXX_CODE_COVERAGE "MyxxCMake: enable code coverage" OFF)

if(MYXX_CODE_COVERAGE)
  find_program(LCOV_EXE NAMES lcov)
  find_program(GENHTML_EXE NAMES genhtml)
endif()

function(myxx_code_coverage TARGET_NAME)
  if(NOT MYXX_CODE_COVERAGE)
    return()
  endif()

  if(NOT ${PROJECT_BINARY_DIR} STREQUAL ${CMAKE_BINARY_DIR})
    return()
  endif()

  set(options)
  set(oneValueArgs)
  set(multiValueArgs EXCLUDE)
  cmake_parse_arguments(ARG "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})

  if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
    set_property(TARGET ${TARGET_NAME} APPEND PROPERTY
        COMPILE_OPTIONS --coverage)
    set_property(TARGET ${TARGET_NAME} APPEND PROPERTY LINK_FLAGS --coverage)
  endif()
  if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    set_property(TARGET ${TARGET_NAME} APPEND PROPERTY
        COMPILE_OPTIONS -fprofile-instr-generate -fcoverage-mapping)
    set_property(TARGET ${TARGET_NAME} APPEND PROPERTY LINK_FLAGS --coverage)
  endif()

  if(LCOV_EXE)
    add_custom_target(${TARGET_NAME}-coverage
      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
      COMMAND ${LCOV_EXE} --test-name ${TARGET_NAME} --output "${TARGET_NAME}.lcov"
              --capture
              --no-external
              --base-directory ${CMAKE_SOURCE_DIR}
              --directory ${CMAKE_BINARY_DIR}
              --exclude "/usr/\\\*"
              --exclude "${CMAKE_BINARY_DIR}/\\\*")
    add_dependencies(${TARGET_NAME}-coverage ${TARGET_NAME})

    if(GENHTML_EXE)
      add_custom_target(${TARGET_NAME}-coverage-report
        WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
        COMMAND ${GENHTML_EXE} --output-directory "${TARGET_NAME}-coverage-html" "${TARGET_NAME}.lcov")
      add_dependencies(${TARGET_NAME}-coverage-report ${TARGET_NAME}-coverage)
    endif()
  endif()
endfunction()