find_program(PROTOC protoc)

function(proto_generate_cpp PROTO_FILE PB_OUT HDR_VAR SRC_VAR)
    get_filename_component(PROTO_FILE_NAME ${PROTO_FILE} NAME_WE)
    get_filename_component(PROTO_FILE_PATH ${PROTO_FILE} ABSOLUTE BASE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
    get_filename_component(PROTO_FILE_DIR ${PROTO_FILE_PATH} DIRECTORY)
    set(PROTO_HDR "${PB_OUT}/${PROTO_FILE_NAME}.pb.h")
    set(PROTO_SRC "${PB_OUT}/${PROTO_FILE_NAME}.pb.cc")
    set(${HDR_VAR} ${${HDR_VAR}} ${PROTO_HDR} PARENT_SCOPE)
    set(${SRC_VAR} ${${SRC_VAR}} ${PROTO_SRC} PARENT_SCOPE)
    if(NOT CMAKE_SCRIPT_MODE_FILE)
        add_custom_command(OUTPUT ${PROTO_HDR} ${PROTO_SRC}
            COMMAND ${PROTOC}
                --cpp_out=${PB_OUT}
                --proto_path ${PROTO_FILE_DIR}
                ${PROTO_FILE_PATH}
            DEPENDS ${PROTO_FILE_PATH}
            COMMENT "Generating nanopb sources for ${PROTO_FILE}")
        set_property(SOURCE ${PROTO_HDR} ${PROTO_SRC} PROPERTY GENERATED TRUE)
        set_property(DIRECTORY . APPEND PROPERTY ADDITIONAL_MAKE_CLEAN_FILES ${PROTO_HDR} ${PROTO_SRC})
    endif()
endfunction()