# - Try to find Eigen3 lib
#
# This module supports requiring a minimum version, e.g. you can do
#   find_package(Eigen3 3.1.2)
# to require version 3.1.2 or newer of Eigen3.
#
# Once done this will define
#
#  EIGEN3_FOUND - system has eigen lib with correct version
#  EIGEN3_INCLUDE_DIR - the eigen include directory
#  EIGEN3_VERSION - eigen version
#
# Copyright (c) 2006, 2007 Montel Laurent, <montel@kde.org>
# Copyright (c) 2008, 2009 Gael Guennebaud, <g.gael@free.fr>
# Copyright (c) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
#
# Redistribution and use is allowed according to the terms of the 2-clause BSD
# license:
#
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
# 1. Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
# 
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

if(NOT Eigen3_FIND_VERSION)
  if(NOT Eigen3_FIND_VERSION_MAJOR)
    set(Eigen3_FIND_VERSION_MAJOR 2)
  endif(NOT Eigen3_FIND_VERSION_MAJOR)
  if(NOT Eigen3_FIND_VERSION_MINOR)
    set(Eigen3_FIND_VERSION_MINOR 91)
  endif(NOT Eigen3_FIND_VERSION_MINOR)
  if(NOT Eigen3_FIND_VERSION_PATCH)
    set(Eigen3_FIND_VERSION_PATCH 0)
  endif(NOT Eigen3_FIND_VERSION_PATCH)

  set(Eigen3_FIND_VERSION "${Eigen3_FIND_VERSION_MAJOR}.${Eigen3_FIND_VERSION_MINOR}.${Eigen3_FIND_VERSION_PATCH}")
endif(NOT Eigen3_FIND_VERSION)

macro(_eigen3_check_version)
  file(READ "${EIGEN3_INCLUDE_DIR}/Eigen/src/Core/util/Macros.h" _eigen3_version_header)

  string(REGEX MATCH "define[ \t]+EIGEN_WORLD_VERSION[ \t]+([0-9]+)" _eigen3_world_version_match "${_eigen3_version_header}")
  set(EIGEN3_WORLD_VERSION "${CMAKE_MATCH_1}")
  string(REGEX MATCH "define[ \t]+EIGEN_MAJOR_VERSION[ \t]+([0-9]+)" _eigen3_major_version_match "${_eigen3_version_header}")
  set(EIGEN3_MAJOR_VERSION "${CMAKE_MATCH_1}")
  string(REGEX MATCH "define[ \t]+EIGEN_MINOR_VERSION[ \t]+([0-9]+)" _eigen3_minor_version_match "${_eigen3_version_header}")
  set(EIGEN3_MINOR_VERSION "${CMAKE_MATCH_1}")

  set(EIGEN3_VERSION ${EIGEN3_WORLD_VERSION}.${EIGEN3_MAJOR_VERSION}.${EIGEN3_MINOR_VERSION})
  if(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})
    set(EIGEN3_VERSION_OK FALSE)
  else(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})
    set(EIGEN3_VERSION_OK TRUE)
  endif(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})

  if(NOT EIGEN3_VERSION_OK)

    message(STATUS "Eigen3 version ${EIGEN3_VERSION} found in ${EIGEN3_INCLUDE_DIR}, "
                   "but at least version ${Eigen3_FIND_VERSION} is required")
  endif(NOT EIGEN3_VERSION_OK)
endmacro(_eigen3_check_version)

if (EIGEN3_INCLUDE_DIR)

  # in cache already
  _eigen3_check_version()
  set(EIGEN3_FOUND ${EIGEN3_VERSION_OK})

else (EIGEN3_INCLUDE_DIR)

  find_path(EIGEN3_INCLUDE_DIR NAMES signature_of_eigen3_matrix_library
      PATHS
      ${CMAKE_INSTALL_PREFIX}/include
      ${KDE4_INCLUDE_DIR}
      PATH_SUFFIXES eigen3 eigen
    )

  if(EIGEN3_INCLUDE_DIR)
    _eigen3_check_version()
  endif(EIGEN3_INCLUDE_DIR)

  include(FindPackageHandleStandardArgs)
  find_package_handle_standard_args(Eigen3 DEFAULT_MSG EIGEN3_INCLUDE_DIR EIGEN3_VERSION_OK)

  mark_as_advanced(EIGEN3_INCLUDE_DIR)

endif(EIGEN3_INCLUDE_DIR)

