find_package(PkgConfig)
if(${PkgConfig_FOUND})
    pkg_check_modules(PC_CUDNN QUIET CUDNN)
endif()

if(NOT "$ENV{LIBRARY_PATH}" STREQUAL "")
    string(REPLACE ":" ";" SYSTEM_LIBRARY_PATHS $ENV{LIBRARY_PATH})
endif()

if(MGE_CUDA_USE_STATIC)
    find_library(CUDNN_LIBRARY 
        NAMES libcudnn_static.a cudnn.lib
        PATHS $ENV{LD_LIBRARY_PATH} ${CUDNN_ROOT_DIR} ${PC_CUDNN_LIBRARY_DIRS} ${CMAKE_INSTALL_PREFIX}
        HINTS ${SYSTEM_LIBRARY_PATHS}
        PATH_SUFFIXES lib lib64
        DOC "CUDNN library." )
else()
    find_library(CUDNN_LIBRARY 
        NAMES libcudnn.so libcudnn.dylib cudnn64.dll
        PATHS $ENV{LD_LIBRARY_PATH} ${CUDNN_ROOT_DIR} ${PC_CUDNN_LIBRARY_DIRS} ${CMAKE_INSTALL_PREFIX}
        HINTS ${SYSTEM_LIBRARY_PATHS}
        PATH_SUFFIXES lib lib64
        DOC "CUDNN library." )
endif()

if(CUDNN_LIBRARY STREQUAL "CUDNN_LIBRARY-NOTFOUND")
    message(FATAL_ERROR "Can not find CuDNN Library")
endif()

get_filename_component(__found_cudnn_root ${CUDNN_LIBRARY}/../.. REALPATH)
find_path(CUDNN_INCLUDE_DIR 
    NAMES cudnn.h
    HINTS $ENV{PC_CUDNN_INCLUDE_DIRS} ${CUDNN_ROOT_DIR} ${CUDA_TOOLKIT_INCLUDE} ${__found_cudnn_root}
    PATH_SUFFIXES include 
    DOC "Path to CUDNN include directory." )

if(CUDNN_INCLUDE_DIR STREQUAL "CUDNN_INCLUDE_DIR-NOTFOUND")
    message(FATAL_ERROR "Can not find CuDNN Library")
endif()

file(READ ${CUDNN_INCLUDE_DIR}/cudnn.h CUDNN_VERSION_FILE_CONTENTS)
string(REGEX MATCH "define CUDNN_MAJOR * +([0-9]+)"
    CUDNN_MAJOR_VERSION "${CUDNN_VERSION_FILE_CONTENTS}")
string(REGEX REPLACE "define CUDNN_MAJOR * +([0-9]+)" "\\1"
    CUDNN_MAJOR_VERSION "${CUDNN_MAJOR_VERSION}")
string(REGEX MATCH "define CUDNN_MINOR * +([0-9]+)"
    CUDNN_MINOR_VERSION "${CUDNN_VERSION_FILE_CONTENTS}")
string(REGEX REPLACE "define CUDNN_MINOR * +([0-9]+)" "\\1"
    CUDNN_MINOR_VERSION "${CUDNN_MINOR_VERSION}")
string(REGEX MATCH "define CUDNN_PATCHLEVEL * +([0-9]+)"
    CUDNN_PATCH_VERSION "${CUDNN_VERSION_FILE_CONTENTS}")
string(REGEX REPLACE "define CUDNN_PATCHLEVEL * +([0-9]+)" "\\1"
    CUDNN_PATCH_VERSION "${CUDNN_PATCH_VERSION}")  
set(CUDNN_VERSION ${CUDNN_MAJOR_VERSION}.${CUDNN_MINOR_VERSION})

if(MGE_CUDA_USE_STATIC)
    add_library(libcudnn STATIC IMPORTED)
else()
    add_library(libcudnn SHARED IMPORTED)
endif()

set_target_properties(libcudnn PROPERTIES
    IMPORTED_LOCATION ${CUDNN_LIBRARY}
    INTERFACE_INCLUDE_DIRECTORIES ${CUDNN_INCLUDE_DIR})

message("-- Found CuDNN: ${__found_cudnn_root} (found version: ${CUDNN_VERSION})")