# A macro wrapper to find OpenCV library
#
# Syntax:  DETECT_OPENCV(OPENCV_MIN_VERSION OPENCV_REQUIRED_COMPONENTS) 
#
# Example: DETECT_OPENCV(3.1.0 core highgui objdetect contrib)
# which try to find OpenCV version 3.1.0
# with internal components "core", "highgui", "objdetect", and "contrib".
#
# Copyright (c) 2010-2019, Gilles Caulier, <caulier dot gilles at gmail dot com>
#
# Redistribution and use is allowed according to the terms of the BSD license.
# For details see the accompanying COPYING-CMAKE-SCRIPTS file.
#

macro(DETECT_OPENCV OPENCV_MIN_VERSION)

    # Reset to avoid picking up extra libraries
    set(OpenCV_LIBS)

    set(OPENCV_REQUIRED_COMPONENTS "${ARGN}")

    find_package(OpenCV COMPONENTS ${OPENCV_REQUIRED_COMPONENTS})

    if(OpenCV_FOUND)

        message(STATUS "OpenCV Root directory is: ${OpenCV_DIR}")

        # check OpenCV version

        if(OpenCV_VERSION)

            message(STATUS "OpenCV: Found version ${OpenCV_VERSION} (required: ${OPENCV_MIN_VERSION})")

            if(${OpenCV_VERSION} VERSION_LESS ${OPENCV_MIN_VERSION})

                message(WARNING "OpenCV: Version is too old.")
                set(OpenCV_FOUND FALSE)

            endif()

        else()

            message(WARNING "OpenCV: Version information not found, your version is probably too old.")
            set(OpenCV_FOUND FALSE)

        endif()

        # There are two versions of FindOpenCV.cmake in the wild, one defining
        # OpenCV_LIBRARIES, the other defining OpenCV_LIBS. Make sure we handle
        # both cases.

        if(NOT OpenCV_LIBRARIES)

            set(OpenCV_LIBRARIES ${OpenCV_LIBS})

        endif()

        # Same story with OpenCV_INCLUDE_DIRS and OpenCV_INCLUDE_DIR:

        if(NOT OpenCV_INCLUDE_DIRS)

            set(OpenCV_INCLUDE_DIRS ${OpenCV_INCLUDE_DIR})

        endif()

        message(STATUS "OpenCV headers: ${OpenCV_INCLUDE_DIRS}")
        message(STATUS "OpenCV libs   : ${OpenCV_LIBRARIES}")

    endif()

endmacro()