#
# This is a CMake makefile.  You can find the cmake utility and
# information about it at http://www.cmake.org
#
#
# This cmake file tries to find installed BLAS and LAPACK libraries.  
# It looks for an installed copy of the Intel MKL library first and then
# attempts to find some other BLAS and LAPACK libraries if you don't have 
# the Intel MKL.
#
#  blas_found               - True if BLAS is available
#  lapack_found             - True if LAPACK is available
#  found_intel_mkl          - True if the Intel MKL library is available
#  found_intel_mkl_headers  - True if Intel MKL headers are available
#  blas_libraries           - link against these to use BLAS library 
#  lapack_libraries         - link against these to use LAPACK library 
#  mkl_libraries            - link against these to use the MKL library
#  mkl_include_dir          - add to the include path to use the MKL library

# setting this makes CMake allow normal looking if else statements
SET(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)

SET(blas_found 0)
SET(lapack_found 0)
SET(found_intel_mkl 0)
SET(found_intel_mkl_headers 0)


if (UNIX)
    message(STATUS "Searching for BLAS and LAPACK")

    if (BUILDING_MATLAB_MEX_FILE)
        find_library(MATLAB_BLAS_LIBRARY mwblas  PATHS ${MATLAB_LIB_FOLDERS} )
        find_library(MATLAB_LAPACK_LIBRARY mwlapack  PATHS ${MATLAB_LIB_FOLDERS} )
        if (MATLAB_BLAS_LIBRARY AND MATLAB_LAPACK_LIBRARY)
            add_subdirectory(external/cblas)
            set(blas_libraries  ${MATLAB_BLAS_LIBRARY} cblas  )
            set(lapack_libraries  ${MATLAB_LAPACK_LIBRARY} )
            set(blas_found 1)
            set(lapack_found 1)
            message(STATUS "Found MATLAB's BLAS and LAPACK libraries")
        endif()
        # Don't try to link to anything other than MATLAB's own internal blas
        # and lapack libraries because doing so generally upsets MATLAB.  So
        # we just end here no matter what.
        return()
    endif()

    # First, search for libraries via pkg-config, which is the cleanest path
    find_package(PkgConfig)
    pkg_check_modules(BLAS_REFERENCE cblas)
    pkg_check_modules(LAPACK_REFERENCE lapack)
    if (BLAS_REFERENCE_FOUND AND LAPACK_REFERENCE_FOUND)
        set(blas_libraries "${BLAS_REFERENCE_LDFLAGS}")
        set(lapack_libraries "${LAPACK_REFERENCE_LDFLAGS}")
        set(blas_found 1)
        set(lapack_found 1)
        set(REQUIRES_LIBS "${REQUIRES_LIBS} cblas lapack")
        message(STATUS "Found BLAS and LAPACK via pkg-config")
        return()
    endif()

    include(CheckTypeSize)
    check_type_size( "void*" SIZE_OF_VOID_PTR)

    if (SIZE_OF_VOID_PTR EQUAL 8)
        set( mkl_search_path
            /opt/intel/mkl/*/lib/em64t
            /opt/intel/mkl/lib/intel64
            /opt/intel/lib/intel64
            )

        find_library(mkl_intel mkl_intel_lp64 ${mkl_search_path})
        mark_as_advanced(mkl_intel)
    else()
        set( mkl_search_path
            /opt/intel/mkl/*/lib/32
            /opt/intel/mkl/lib/ia32
            /opt/intel/lib/ia32
            )

        find_library(mkl_intel mkl_intel ${mkl_search_path})
        mark_as_advanced(mkl_intel)
    endif()

   include(CheckLibraryExists)

    # Get mkl_include_dir
    set(mkl_include_search_path
        /opt/intel/mkl/include
        /opt/intel/include
    )
    find_path(mkl_include_dir mkl_version.h ${mkl_include_search_path})

    # Search for the needed libraries from the MKL.  We will try to link against the mkl_rt
    # file first since this way avoids linking bugs in some cases.
    find_library(mkl_rt mkl_rt ${mkl_search_path})
    mark_as_advanced(  mkl_rt )
    # if we found the MKL 
    if ( mkl_rt)
        set(mkl_libraries  ${mkl_rt} )
        set(blas_libraries  ${mkl_rt} )
        set(lapack_libraries  ${mkl_rt} )
        set(blas_found 1)
        set(lapack_found 1)
        set(found_intel_mkl 1)
        message(STATUS "Found Intel MKL BLAS/LAPACK library")
    endif()

    if (NOT found_intel_mkl)
        # Search for the needed libraries from the MKL.  This time try looking for a different
        # set of MKL files and try to link against those.
        find_library(mkl_core mkl_core ${mkl_search_path})
        find_library(mkl_thread mkl_intel_thread ${mkl_search_path})
        find_library(mkl_iomp iomp5 ${mkl_search_path})
        find_library(mkl_pthread pthread ${mkl_search_path})

        mark_as_advanced( mkl_intel mkl_core mkl_thread mkl_iomp mkl_pthread)
        # If we found the MKL 
        if (mkl_intel AND mkl_core AND mkl_thread AND mkl_iomp AND mkl_pthread)
            set(mkl_libraries ${mkl_intel} ${mkl_core} ${mkl_thread} ${mkl_iomp} ${mkl_pthread})
            set(blas_libraries ${mkl_intel} ${mkl_core} ${mkl_thread} ${mkl_iomp} ${mkl_pthread})
            set(lapack_libraries ${mkl_intel} ${mkl_core} ${mkl_thread} ${mkl_iomp} ${mkl_pthread})
            set(blas_found 1)
            set(lapack_found 1)
            set(found_intel_mkl 1)
            message(STATUS "Found Intel MKL BLAS/LAPACK library")
        endif()
    endif()

    if (found_intel_mkl AND mkl_include_dir)
        set(found_intel_mkl_headers 1)
    endif()

   # try to find some other LAPACK libraries if we didn't find the MKL
   set(extra_paths
        /usr/lib64
        /usr/lib64/atlas-sse3
        /usr/lib64/atlas-sse2
        /usr/lib64/atlas
        /usr/lib
        /usr/lib/atlas-sse3
        /usr/lib/atlas-sse2
        /usr/lib/atlas
        /usr/lib/openblas-base
        /opt/OpenBLAS/lib
        $ENV{OPENBLAS_HOME}/lib
        )

   INCLUDE (CheckFunctionExists)

   if (NOT blas_found)
      find_library(cblas_lib openblas PATHS ${extra_paths})
      if (cblas_lib)
         set(blas_libraries ${cblas_lib})
         set(blas_found 1)
         message(STATUS "Found OpenBLAS library")
         set(CMAKE_REQUIRED_LIBRARIES ${blas_libraries})
         # If you compiled OpenBLAS with LAPACK in it then it should have the
         # sgetrf_single function in it.  So if we find that function in
         # OpenBLAS then just use OpenBLAS's LAPACK. 
         CHECK_FUNCTION_EXISTS(sgetrf_single OPENBLAS_HAS_LAPACK)
         if (OPENBLAS_HAS_LAPACK)
            message(STATUS "Using OpenBLAS's built in LAPACK")
            # set(lapack_libraries gfortran) 
            set(lapack_found 1)
         endif()
      endif()
      mark_as_advanced( cblas_lib)
   endif()


   if (NOT lapack_found)
      find_library(lapack_lib NAMES lapack lapack-3 PATHS ${extra_paths})
      if (lapack_lib)
         set(lapack_libraries ${lapack_lib})
         set(lapack_found 1)
         message(STATUS "Found LAPACK library")
      endif()
      mark_as_advanced( lapack_lib)
   endif()

   
   # try to find some other BLAS libraries if we didn't find the MKL
   
   if (NOT blas_found)
      find_library(atlas_lib atlas PATHS ${extra_paths})
      find_library(cblas_lib cblas PATHS ${extra_paths})
      if (atlas_lib AND cblas_lib)
         set(blas_libraries ${atlas_lib} ${cblas_lib})
         set(blas_found 1)
         message(STATUS "Found ATLAS BLAS library")
      endif()
      mark_as_advanced( atlas_lib cblas_lib)
   endif()

   # CentOS 7 atlas
   if (NOT blas_found)
      find_library(tatlas_lib tatlas PATHS ${extra_paths})
      find_library(satlas_lib satlas PATHS ${extra_paths})
      if (tatlas_lib AND satlas_lib )
         set(blas_libraries ${tatlas_lib} ${satlas_lib})
         set(blas_found 1)
         message(STATUS "Found ATLAS BLAS library")
      endif()
      mark_as_advanced( tatlas_lib satlas_lib)
   endif()


   if (NOT blas_found)
      find_library(cblas_lib cblas PATHS ${extra_paths})
      if (cblas_lib)
         set(blas_libraries ${cblas_lib})
         set(blas_found 1)
         message(STATUS "Found CBLAS library")
      endif()
      mark_as_advanced( cblas_lib)
   endif()

   
   if (NOT blas_found)
      find_library(generic_blas blas PATHS ${extra_paths})
      if (generic_blas)
         set(blas_libraries ${generic_blas})
         set(blas_found 1)
         message(STATUS "Found BLAS library")
      endif()
      mark_as_advanced( generic_blas)
   endif()




   # Make sure we really found a CBLAS library.  That is, it needs to expose
   # the proper cblas link symbols.  So here we test if one of them is present
   # and assume everything is good if it is. Note that we don't do this check if
   # we found the Intel MKL since for some reason CHECK_FUNCTION_EXISTS doesn't work
   # with it.  But it's fine since the MKL should always have cblas.
   if (blas_found AND NOT found_intel_mkl)
      set(CMAKE_REQUIRED_LIBRARIES ${blas_libraries})
      CHECK_FUNCTION_EXISTS(cblas_ddot HAVE_CBLAS)
      if (NOT HAVE_CBLAS)
         message(STATUS "BLAS library does not have cblas symbols, so dlib will not use BLAS or LAPACK")
         set(blas_found 0)
         set(lapack_found 0)
      endif()
   endif()


   if (NOT blas_found)
      message(" *****************************************************************************")
      message(" *** No BLAS library found so using dlib's built in BLAS.  However, if you ***")
      message(" *** install an optimized BLAS such as OpenBLAS or the Intel MKL your code ***")
      message(" *** will run faster.  On Ubuntu you can install OpenBLAS by executing:    ***")
      message(" ***    sudo apt-get install libopenblas-dev liblapack-dev                 ***")
      message(" *** Or you can easily install OpenBLAS from source by downloading the     ***")
      message(" *** source tar file from http://www.openblas.net, extracting it, and      ***")
      message(" *** running:                                                              ***")
      message(" ***    make; sudo make install                                            ***")
      message(" *****************************************************************************")
   endif()

elseif(WIN32 AND NOT MINGW)
    message(STATUS "Searching for BLAS and LAPACK")

    include(CheckTypeSize)
    check_type_size( "void*" SIZE_OF_VOID_PTR)
    if (SIZE_OF_VOID_PTR EQUAL 8)
        set( mkl_search_path
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries_*/windows/mkl/lib/intel64" 
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries_*/windows/compiler/lib/intel64" 
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries/windows/compiler/lib/intel64" 
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries/windows/mkl/lib/intel64"
            "C:/Program Files (x86)/Intel/Composer XE/mkl/lib/intel64"
            "C:/Program Files (x86)/Intel/Composer XE/compiler/lib/intel64"
            "C:/Program Files/Intel/Composer XE/mkl/lib/intel64"
            "C:/Program Files/Intel/Composer XE/compiler/lib/intel64"
            )
        find_library(mkl_intel  mkl_intel_lp64 ${mkl_search_path})
    else()
        set( mkl_search_path
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries_*/windows/mkl/lib/ia32" 
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries_*/windows/compiler/lib/ia32"
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries/windows/mkl/lib/ia32" 
            "C:/Program Files (x86)/IntelSWTools/compilers_and_libraries/windows/compiler/lib/ia32"
            "C:/Program Files (x86)/Intel/Composer XE/mkl/lib/ia32"
            "C:/Program Files (x86)/Intel/Composer XE/compiler/lib/ia32"
            "C:/Program Files/Intel/Composer XE/mkl/lib/ia32"
            "C:/Program Files/Intel/Composer XE/compiler/lib/ia32"
            )
        find_library(mkl_intel  mkl_intel_c ${mkl_search_path})
    endif()

   INCLUDE (CheckFunctionExists)

    # Search for the needed libraries from the MKL.  
    find_library(mkl_core mkl_core ${mkl_search_path})
    find_library(mkl_thread mkl_intel_thread ${mkl_search_path})
    find_library(mkl_iomp libiomp5md ${mkl_search_path})

    mark_as_advanced( mkl_intel mkl_core mkl_thread  mkl_iomp)
    # If we found the MKL 
    if (mkl_intel AND mkl_core AND mkl_thread AND mkl_iomp )
        set(blas_libraries ${mkl_intel} ${mkl_core} ${mkl_thread} ${mkl_iomp}  )
        set(lapack_libraries ${mkl_intel} ${mkl_core} ${mkl_thread} ${mkl_iomp} )
        set(blas_found 1)
        set(lapack_found 1)
        message(STATUS "Found Intel MKL BLAS/LAPACK library")

        # Make sure the version of the Intel MKL we found is compatible with
        # the compiler we are using.  One way to do this check is to see if we can
        # link to it right now.
        set(CMAKE_REQUIRED_LIBRARIES ${blas_libraries})
        CHECK_FUNCTION_EXISTS(cblas_ddot HAVE_CBLAS)
        if (NOT HAVE_CBLAS)
            message("BLAS library does not have cblas symbols, so dlib will not use BLAS or LAPACK")
            set(blas_found 0)
            set(lapack_found 0)
        endif()

        if (MSVC AND blas_found)
            # need to set /bigobj when statically linking with the MKL on
            # visual studio or it doesn't work right.
            if (NOT CMAKE_CXX_FLAGS MATCHES "/bigobj")
                set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /bigobj" 
                    CACHE STRING "Flags used by the compiler during all C++ builds." 
                    FORCE)
            endif ()
        endif()
    endif()


endif()



