#.rst:
# CMakePackageConfigHelpers
# -------------------------
#
# CONFIGURE_PACKAGE_CONFIG_FILE(), WRITE_BASIC_PACKAGE_VERSION_FILE()
#
#
#
# ::
#
#     CONFIGURE_PACKAGE_CONFIG_FILE(<input> <output> INSTALL_DESTINATION <path>
#                                                    [PATH_VARS <var1> <var2> ... <varN>]
#                                                    [NO_SET_AND_CHECK_MACRO]
#                                                    [NO_CHECK_REQUIRED_COMPONENTS_MACRO])
#
#
#
# CONFIGURE_PACKAGE_CONFIG_FILE() should be used instead of the plain
# configure_file() command when creating the <Name>Config.cmake or
# <Name>-config.cmake file for installing a project or library.  It
# helps making the resulting package relocatable by avoiding hardcoded
# paths in the installed Config.cmake file.
#
# In a FooConfig.cmake file there may be code like this to make the
# install destinations know to the using project:
#
# ::
#
#    set(FOO_INCLUDE_DIR   "@CMAKE_INSTALL_FULL_INCLUDEDIR@" )
#    set(FOO_DATA_DIR   "@CMAKE_INSTALL_PREFIX@/@RELATIVE_DATA_INSTALL_DIR@" )
#    set(FOO_ICONS_DIR   "@CMAKE_INSTALL_PREFIX@/share/icons" )
#    ...logic to determine installedPrefix from the own location...
#    set(FOO_CONFIG_DIR  "${installedPrefix}/@CONFIG_INSTALL_DIR@" )
#
# All 4 options shown above are not sufficient, since the first 3
# hardcode the absolute directory locations, and the 4th case works only
# if the logic to determine the installedPrefix is correct, and if
# CONFIG_INSTALL_DIR contains a relative path, which in general cannot
# be guaranteed.  This has the effect that the resulting FooConfig.cmake
# file would work poorly under Windows and OSX, where users are used to
# choose the install location of a binary package at install time,
# independent from how CMAKE_INSTALL_PREFIX was set at build/cmake time.
#
# Using CONFIGURE_PACKAGE_CONFIG_FILE() helps.  If used correctly, it
# makes the resulting FooConfig.cmake file relocatable.  Usage:
#
# ::
#
#    1. write a FooConfig.cmake.in file as you are used to
#    2. insert a line containing only the string "@PACKAGE_INIT@"
#    3. instead of set(FOO_DIR "@SOME_INSTALL_DIR@"), use set(FOO_DIR "@PACKAGE_SOME_INSTALL_DIR@")
#       (this must be after the @PACKAGE_INIT@ line)
#    4. instead of using the normal configure_file(), use CONFIGURE_PACKAGE_CONFIG_FILE()
#
#
#
# The <input> and <output> arguments are the input and output file, the
# same way as in configure_file().
#
# The <path> given to INSTALL_DESTINATION must be the destination where
# the FooConfig.cmake file will be installed to.  This can either be a
# relative or absolute path, both work.
#
# The variables <var1> to <varN> given as PATH_VARS are the variables
# which contain install destinations.  For each of them the macro will
# create a helper variable PACKAGE_<var...>.  These helper variables
# must be used in the FooConfig.cmake.in file for setting the installed
# location.  They are calculated by CONFIGURE_PACKAGE_CONFIG_FILE() so
# that they are always relative to the installed location of the
# package.  This works both for relative and also for absolute
# locations.  For absolute locations it works only if the absolute
# location is a subdirectory of CMAKE_INSTALL_PREFIX.
#
# By default configure_package_config_file() also generates two helper
# macros, set_and_check() and check_required_components() into the
# FooConfig.cmake file.
#
# set_and_check() should be used instead of the normal set() command for
# setting directories and file locations.  Additionally to setting the
# variable it also checks that the referenced file or directory actually
# exists and fails with a FATAL_ERROR otherwise.  This makes sure that
# the created FooConfig.cmake file does not contain wrong references.
# When using the NO_SET_AND_CHECK_MACRO, this macro is not generated
# into the FooConfig.cmake file.
#
# check_required_components(<package_name>) should be called at the end
# of the FooConfig.cmake file if the package supports components.  This
# macro checks whether all requested, non-optional components have been
# found, and if this is not the case, sets the Foo_FOUND variable to
# FALSE, so that the package is considered to be not found.  It does
# that by testing the Foo_<Component>_FOUND variables for all requested
# required components.  When using the NO_CHECK_REQUIRED_COMPONENTS
# option, this macro is not generated into the FooConfig.cmake file.
#
# For an example see below the documentation for
# WRITE_BASIC_PACKAGE_VERSION_FILE().
#
#
#
# ::
#
#   WRITE_BASIC_PACKAGE_VERSION_FILE( filename [VERSION major.minor.patch] COMPATIBILITY (AnyNewerVersion|SameMajorVersion|ExactVersion) )
#
#
#
# Writes a file for use as <package>ConfigVersion.cmake file to
# <filename>.  See the documentation of find_package() for details on
# this.
#
# ::
#
#     filename is the output filename, it should be in the build tree.
#     major.minor.patch is the version number of the project to be installed
#
# If no ``VERSION`` is given, the :variable:`PROJECT_VERSION` variable
# is used.  If this hasn't been set, it errors out.
#
# The COMPATIBILITY mode AnyNewerVersion means that the installed
# package version will be considered compatible if it is newer or
# exactly the same as the requested version.  This mode should be used
# for packages which are fully backward compatible, also across major
# versions.  If SameMajorVersion is used instead, then the behaviour
# differs from AnyNewerVersion in that the major version number must be
# the same as requested, e.g.  version 2.0 will not be considered
# compatible if 1.0 is requested.  This mode should be used for packages
# which guarantee backward compatibility within the same major version.
# If ExactVersion is used, then the package is only considered
# compatible if the requested version matches exactly its own version
# number (not considering the tweak version).  For example, version
# 1.2.3 of a package is only considered compatible to requested version
# 1.2.3.  This mode is for packages without compatibility guarantees.
# If your project has more elaborated version matching rules, you will
# need to write your own custom ConfigVersion.cmake file instead of
# using this macro.
#
# Internally, this macro executes configure_file() to create the
# resulting version file.  Depending on the COMPATIBLITY, either the
# file BasicConfigVersion-SameMajorVersion.cmake.in or
# BasicConfigVersion-AnyNewerVersion.cmake.in is used.  Please note that
# these two files are internal to CMake and you should not call
# configure_file() on them yourself, but they can be used as starting
# point to create more sophisticted custom ConfigVersion.cmake files.
#
#
#
# Example using both configure_package_config_file() and
# write_basic_package_version_file(): CMakeLists.txt:
#
# ::
#
#    set(INCLUDE_INSTALL_DIR include/ ... CACHE )
#    set(LIB_INSTALL_DIR lib/ ... CACHE )
#    set(SYSCONFIG_INSTALL_DIR etc/foo/ ... CACHE )
#    ...
#    include(CMakePackageConfigHelpers)
#    configure_package_config_file(FooConfig.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/FooConfig.cmake
#                                  INSTALL_DESTINATION ${LIB_INSTALL_DIR}/Foo/cmake
#                                  PATH_VARS INCLUDE_INSTALL_DIR SYSCONFIG_INSTALL_DIR)
#    write_basic_package_version_file(${CMAKE_CURRENT_BINARY_DIR}/FooConfigVersion.cmake
#                                     VERSION 1.2.3
#                                     COMPATIBILITY SameMajorVersion )
#    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/FooConfig.cmake ${CMAKE_CURRENT_BINARY_DIR}/FooConfigVersion.cmake
#            DESTINATION ${LIB_INSTALL_DIR}/Foo/cmake )
#
#
#
# With a FooConfig.cmake.in:
#
# ::
#
#    set(FOO_VERSION x.y.z)
#    ...
#    @PACKAGE_INIT@
#    ...
#    set_and_check(FOO_INCLUDE_DIR "@PACKAGE_INCLUDE_INSTALL_DIR@")
#    set_and_check(FOO_SYSCONFIG_DIR "@PACKAGE_SYSCONFIG_INSTALL_DIR@")
#
#
#
# ::
#
#    check_required_components(Foo)


#=============================================================================
# Copyright 2012 Alexander Neundorf <neundorf@kde.org>
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
#  License text for the above reference.)

include(CMakeParseArguments)

include(WriteBasicConfigVersionFile)

macro(WRITE_BASIC_PACKAGE_VERSION_FILE)
  write_basic_config_version_file(${ARGN})
endmacro()

set(cfpch_dir ${CMAKE_CURRENT_LIST_DIR})

function(CONFIGURE_PACKAGE_CONFIG_FILE _inputFile _outputFile)
  set(options NO_SET_AND_CHECK_MACRO NO_CHECK_REQUIRED_COMPONENTS_MACRO)
  set(oneValueArgs INSTALL_DESTINATION )
  set(multiValueArgs PATH_VARS )

  cmake_parse_arguments(CCF "${options}" "${oneValueArgs}" "${multiValueArgs}"  ${ARGN})

  if(CCF_UNPARSED_ARGUMENTS)
    message(FATAL_ERROR "Unknown keywords given to CONFIGURE_PACKAGE_CONFIG_FILE(): \"${CCF_UNPARSED_ARGUMENTS}\"")
  endif()

  if(NOT CCF_INSTALL_DESTINATION)
    message(FATAL_ERROR "No INSTALL_DESTINATION given to CONFIGURE_PACKAGE_CONFIG_FILE()")
  endif()

  if(IS_ABSOLUTE "${CCF_INSTALL_DESTINATION}")
    set(absInstallDir "${CCF_INSTALL_DESTINATION}")
  else()
    set(absInstallDir "${CMAKE_INSTALL_PREFIX}/${CCF_INSTALL_DESTINATION}")
  endif()

  file(RELATIVE_PATH PACKAGE_RELATIVE_PATH "${absInstallDir}" "${CMAKE_INSTALL_PREFIX}" )

  foreach(var ${CCF_PATH_VARS})
    if(NOT DEFINED ${var})
      message(FATAL_ERROR "Variable ${var} does not exist")
    else()
      if(IS_ABSOLUTE "${${var}}")
        string(REPLACE "${CMAKE_INSTALL_PREFIX}" "\${PACKAGE_PREFIX_DIR}"
                        PACKAGE_${var} "${${var}}")
      else()
        set(PACKAGE_${var} "\${PACKAGE_PREFIX_DIR}/${${var}}")
      endif()
    endif()
  endforeach()

  get_filename_component(inputFileName "${_inputFile}" NAME)

  set(PACKAGE_INIT "
####### Expanded from @PACKAGE_INIT@ by configure_package_config_file() #######
####### Any changes to this file will be overwritten by the next CMake run ####
####### The input file was ${inputFileName}                            ########

get_filename_component(PACKAGE_PREFIX_DIR \"\${CMAKE_CURRENT_LIST_DIR}/${PACKAGE_RELATIVE_PATH}\" ABSOLUTE)
")

  if("${absInstallDir}" MATCHES "^(/usr)?/lib(64)?/.+")
    # Handle "/usr move" symlinks created by some Linux distros.
    set(PACKAGE_INIT "${PACKAGE_INIT}
# Use original install prefix when loaded through a \"/usr move\"
# cross-prefix symbolic link such as /lib -> /usr/lib.
get_filename_component(_realCurr \"\${CMAKE_CURRENT_LIST_DIR}\" REALPATH)
get_filename_component(_realOrig \"${absInstallDir}\" REALPATH)
if(_realCurr STREQUAL _realOrig)
  set(PACKAGE_PREFIX_DIR \"${CMAKE_INSTALL_PREFIX}\")
endif()
unset(_realOrig)
unset(_realCurr)
")
  endif()

  if(NOT CCF_NO_SET_AND_CHECK_MACRO)
    set(PACKAGE_INIT "${PACKAGE_INIT}
macro(set_and_check _var _file)
  set(\${_var} \"\${_file}\")
  if(NOT EXISTS \"\${_file}\")
    message(FATAL_ERROR \"File or directory \${_file} referenced by variable \${_var} does not exist !\")
  endif()
endmacro()
")
  endif()


  if(NOT CCF_NO_CHECK_REQUIRED_COMPONENTS_MACRO)
    set(PACKAGE_INIT "${PACKAGE_INIT}
macro(check_required_components _NAME)
  foreach(comp \${\${_NAME}_FIND_COMPONENTS})
    if(NOT \${_NAME}_\${comp}_FOUND)
      if(\${_NAME}_FIND_REQUIRED_\${comp})
        set(\${_NAME}_FOUND FALSE)
      endif()
    endif()
  endforeach()
endmacro()
")
  endif()

  set(PACKAGE_INIT "${PACKAGE_INIT}
####################################################################################")

  configure_file("${_inputFile}" "${_outputFile}" @ONLY)

endfunction()