option (USE_INTERNAL_RE2_LIBRARY "Set to FALSE to use system re2 library instead of bundled [slower]" ${NOT_UNBUNDLED})

if(NOT EXISTS "${ClickHouse_SOURCE_DIR}/contrib/re2/CMakeLists.txt")
    if(USE_INTERNAL_RE2_LIBRARY)
        message(WARNING "submodule contrib/re2 is missing. to fix try run: \n git submodule update --init")
        message (${RECONFIGURE_MESSAGE_LEVEL} "Can't find internal re2 library")
    endif()
    set(USE_INTERNAL_RE2_LIBRARY 0)
    set(MISSING_INTERNAL_RE2_LIBRARY 1)
endif()

if (NOT USE_INTERNAL_RE2_LIBRARY)
    find_library (RE2_LIBRARY re2)
    find_path (RE2_INCLUDE_DIR NAMES re2/re2.h PATHS ${RE2_INCLUDE_PATHS})
    if (NOT RE2_LIBRARY OR NOT RE2_INCLUDE_DIR)
        message (${RECONFIGURE_MESSAGE_LEVEL} "Can't find system re2 library")
    endif ()
endif ()

string(FIND ${CMAKE_CURRENT_BINARY_DIR} " " _have_space)
if(_have_space GREATER 0)
    message(WARNING "Using spaces in build path [${CMAKE_CURRENT_BINARY_DIR}] highly not recommended. Library re2st will be disabled.")
    set (MISSING_INTERNAL_RE2_ST_LIBRARY 1)
endif()

if (RE2_LIBRARY AND RE2_INCLUDE_DIR)
    set (RE2_ST_LIBRARY ${RE2_LIBRARY})
elseif (NOT MISSING_INTERNAL_RE2_LIBRARY)
    set (USE_INTERNAL_RE2_LIBRARY 1)
    set (RE2_LIBRARY re2)
    set (RE2_INCLUDE_DIR "${ClickHouse_SOURCE_DIR}/contrib/re2")
    if (NOT MISSING_INTERNAL_RE2_ST_LIBRARY)
        set (RE2_ST_LIBRARY re2_st)
        set (USE_RE2_ST 1)
    else ()
        set (RE2_ST_LIBRARY ${RE2_LIBRARY})
        message (${RECONFIGURE_MESSAGE_LEVEL} "Using internal re2 library instead of re2_st")
    endif ()
endif ()

message (STATUS "Using re2: ${RE2_INCLUDE_DIR} : ${RE2_LIBRARY}; ${RE2_ST_INCLUDE_DIR} : ${RE2_ST_LIBRARY}")