# - 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

# 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()

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()